Merge branch 'master' of github.com:grpc/grpc into removed_expiration_interval

50 files changed, 1266 insertions, 566 deletions

diff --git a/test/cpp/client/BUILD b/test/cpp/client/BUILD
new file mode 100644
index 0000000000..12825e88c2
--- /dev/null
+++ b/test/cpp/client/BUILD
@@ -0,0 +1,51 @@
+# Copyright 2017 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+licenses(["notice"])  # Apache v2
+
+load("//bazel:grpc_build_system.bzl", "grpc_cc_library", "grpc_cc_test", "grpc_package")
+
+grpc_package(name = "test/cpp/client")
+
+grpc_cc_test(
+    name = "credentials_test",
+    srcs = ["credentials_test.cc"],
+    external_deps = [
+        "gtest",
+    ],
+    deps = [
+        "//:gpr",
+        "//:grpc",
+        "//:grpc++",
+    ],
+)
+
+grpc_cc_test(
+    name = "client_channel_stress_test",
+    srcs = ["client_channel_stress_test.cc"],
+    deps = [
+        "//:gpr",
+        "//:grpc",
+        "//:grpc++",
+        "//:grpc_resolver_fake",
+        "//src/proto/grpc/lb/v1:load_balancer_proto",
+        "//src/proto/grpc/testing:echo_messages_proto",
+        "//src/proto/grpc/testing:echo_proto",
+        "//src/proto/grpc/testing/duplicate:echo_duplicate_proto",
+        "//test/core/util:gpr_test_util",
+        "//test/core/util:grpc_test_util",
+        "//test/cpp/end2end:test_service_impl",
+        "//test/cpp/util:test_util",
+    ],
+)
diff --git a/test/cpp/client/client_channel_stress_test.cc b/test/cpp/client/client_channel_stress_test.cc
new file mode 100644
index 0000000000..0954b28df0
--- /dev/null
+++ b/test/cpp/client/client_channel_stress_test.cc
@@ -0,0 +1,327 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <atomic>
+#include <memory>
+#include <mutex>
+#include <sstream>
+#include <thread>
+
+#include <grpc++/channel.h>
+#include <grpc++/client_context.h>
+#include <grpc++/create_channel.h>
+#include <grpc++/server.h>
+#include <grpc++/server_builder.h>
+#include <grpc/grpc.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/thd.h>
+#include <grpc/support/time.h>
+
+#include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
+#include "src/core/lib/iomgr/sockaddr.h"
+
+#include "test/core/util/port.h"
+#include "test/core/util/test_config.h"
+#include "test/cpp/end2end/test_service_impl.h"
+
+#include "src/proto/grpc/lb/v1/load_balancer.grpc.pb.h"
+#include "src/proto/grpc/testing/echo.grpc.pb.h"
+
+using grpc::lb::v1::LoadBalanceRequest;
+using grpc::lb::v1::LoadBalanceResponse;
+using grpc::lb::v1::LoadBalancer;
+
+namespace grpc {
+namespace testing {
+namespace {
+
+const size_t kNumBackends = 10;
+const size_t kNumBalancers = 5;
+const size_t kNumClientThreads = 100;
+const int kResolutionUpdateIntervalMs = 50;
+const int kServerlistUpdateIntervalMs = 10;
+const int kTestDurationSec = 30;
+
+using BackendServiceImpl = TestServiceImpl;
+
+class BalancerServiceImpl : public LoadBalancer::Service {
+ public:
+  using Stream = ServerReaderWriter<LoadBalanceResponse, LoadBalanceRequest>;
+
+  explicit BalancerServiceImpl(const std::vector<int>& all_backend_ports)
+      : all_backend_ports_(all_backend_ports) {}
+
+  Status BalanceLoad(ServerContext* context, Stream* stream) override {
+    gpr_log(GPR_INFO, "LB[%p]: Start BalanceLoad.", this);
+    LoadBalanceRequest request;
+    stream->Read(&request);
+    while (!shutdown_) {
+      stream->Write(BuildRandomResponseForBackends());
+      std::this_thread::sleep_for(
+          std::chrono::milliseconds(kServerlistUpdateIntervalMs));
+    }
+    gpr_log(GPR_INFO, "LB[%p]: Finish BalanceLoad.", this);
+    return Status::OK;
+  }
+
+  void Shutdown() { shutdown_ = true; }
+
+ private:
+  grpc::string Ip4ToPackedString(const char* ip_str) {
+    struct in_addr ip4;
+    GPR_ASSERT(inet_pton(AF_INET, ip_str, &ip4) == 1);
+    return grpc::string(reinterpret_cast<const char*>(&ip4), sizeof(ip4));
+  }
+
+  LoadBalanceResponse BuildRandomResponseForBackends() {
+    // Generate a random serverlist with varying size (if N =
+    // all_backend_ports_.size(), num_non_drop_entry is in [0, 2N],
+    // num_drop_entry is in [0, N]), order, duplicate, and drop rate.
+    size_t num_non_drop_entry =
+        std::rand() % (all_backend_ports_.size() * 2 + 1);
+    size_t num_drop_entry = std::rand() % (all_backend_ports_.size() + 1);
+    std::vector<int> random_backend_indices;
+    for (size_t i = 0; i < num_non_drop_entry; ++i) {
+      random_backend_indices.push_back(std::rand() % all_backend_ports_.size());
+    }
+    for (size_t i = 0; i < num_drop_entry; ++i) {
+      random_backend_indices.push_back(-1);
+    }
+    std::random_shuffle(random_backend_indices.begin(),
+                        random_backend_indices.end());
+    // Build the response according to the random list generated above.
+    LoadBalanceResponse response;
+    for (int index : random_backend_indices) {
+      auto* server = response.mutable_server_list()->add_servers();
+      if (index < 0) {
+        server->set_drop(true);
+        server->set_load_balance_token("load_balancing");
+      } else {
+        server->set_ip_address(Ip4ToPackedString("127.0.0.1"));
+        server->set_port(all_backend_ports_[index]);
+      }
+    }
+    return response;
+  }
+
+  std::atomic_bool shutdown_{false};
+  const std::vector<int> all_backend_ports_;
+};
+
+class ClientChannelStressTest {
+ public:
+  void Run() {
+    Start();
+    // Keep updating resolution for the test duration.
+    gpr_log(GPR_INFO, "Start updating resolution.");
+    const auto wait_duration =
+        std::chrono::milliseconds(kResolutionUpdateIntervalMs);
+    std::vector<AddressData> addresses;
+    auto start_time = std::chrono::steady_clock::now();
+    while (true) {
+      if (std::chrono::duration_cast<std::chrono::seconds>(
+              std::chrono::steady_clock::now() - start_time)
+              .count() > kTestDurationSec) {
+        break;
+      }
+      // Generate a random subset of balancers.
+      addresses.clear();
+      for (const auto& balancer_server : balancer_servers_) {
+        // Select each address with probability of 0.8.
+        if (std::rand() % 10 < 8) {
+          addresses.emplace_back(AddressData{balancer_server.port_, true, ""});
+        }
+      }
+      std::random_shuffle(addresses.begin(), addresses.end());
+      SetNextResolution(addresses);
+      std::this_thread::sleep_for(wait_duration);
+    }
+    gpr_log(GPR_INFO, "Finish updating resolution.");
+    Shutdown();
+  }
+
+ private:
+  template <typename T>
+  struct ServerThread {
+    explicit ServerThread(const grpc::string& type,
+                          const grpc::string& server_host, T* service)
+        : type_(type), service_(service) {
+      std::mutex mu;
+      // We need to acquire the lock here in order to prevent the notify_one
+      // by ServerThread::Start from firing before the wait below is hit.
+      std::unique_lock<std::mutex> lock(mu);
+      port_ = grpc_pick_unused_port_or_die();
+      gpr_log(GPR_INFO, "starting %s server on port %d", type_.c_str(), port_);
+      std::condition_variable cond;
+      thread_.reset(new std::thread(
+          std::bind(&ServerThread::Start, this, server_host, &mu, &cond)));
+      cond.wait(lock);
+      gpr_log(GPR_INFO, "%s server startup complete", type_.c_str());
+    }
+
+    void Start(const grpc::string& server_host, std::mutex* mu,
+               std::condition_variable* cond) {
+      // We need to acquire the lock here in order to prevent the notify_one
+      // below from firing before its corresponding wait is executed.
+      std::lock_guard<std::mutex> lock(*mu);
+      std::ostringstream server_address;
+      server_address << server_host << ":" << port_;
+      ServerBuilder builder;
+      builder.AddListeningPort(server_address.str(),
+                               InsecureServerCredentials());
+      builder.RegisterService(service_);
+      server_ = builder.BuildAndStart();
+      cond->notify_one();
+    }
+
+    void Shutdown() {
+      gpr_log(GPR_INFO, "%s about to shutdown", type_.c_str());
+      server_->Shutdown(grpc_timeout_milliseconds_to_deadline(0));
+      thread_->join();
+      gpr_log(GPR_INFO, "%s shutdown completed", type_.c_str());
+    }
+
+    int port_;
+    grpc::string type_;
+    std::unique_ptr<Server> server_;
+    T* service_;
+    std::unique_ptr<std::thread> thread_;
+  };
+
+  struct AddressData {
+    int port;
+    bool is_balancer;
+    grpc::string balancer_name;
+  };
+
+  void SetNextResolution(const std::vector<AddressData>& address_data) {
+    grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+    grpc_lb_addresses* addresses =
+        grpc_lb_addresses_create(address_data.size(), nullptr);
+    for (size_t i = 0; i < address_data.size(); ++i) {
+      char* lb_uri_str;
+      gpr_asprintf(&lb_uri_str, "ipv4:127.0.0.1:%d", address_data[i].port);
+      grpc_uri* lb_uri = grpc_uri_parse(&exec_ctx, lb_uri_str, true);
+      GPR_ASSERT(lb_uri != nullptr);
+      grpc_lb_addresses_set_address_from_uri(
+          addresses, i, lb_uri, address_data[i].is_balancer,
+          address_data[i].balancer_name.c_str(), nullptr);
+      grpc_uri_destroy(lb_uri);
+      gpr_free(lb_uri_str);
+    }
+    grpc_arg fake_addresses = grpc_lb_addresses_create_channel_arg(addresses);
+    grpc_channel_args fake_result = {1, &fake_addresses};
+    grpc_fake_resolver_response_generator_set_response(
+        &exec_ctx, response_generator_, &fake_result);
+    grpc_lb_addresses_destroy(&exec_ctx, addresses);
+    grpc_exec_ctx_finish(&exec_ctx);
+  }
+
+  void KeepSendingRequests() {
+    gpr_log(GPR_INFO, "Start sending requests.");
+    while (!shutdown_) {
+      ClientContext context;
+      context.set_deadline(grpc_timeout_milliseconds_to_deadline(1000));
+      EchoRequest request;
+      request.set_message("test");
+      EchoResponse response;
+      {
+        std::lock_guard<std::mutex> lock(stub_mutex_);
+        stub_->Echo(&context, request, &response);
+      }
+    }
+    gpr_log(GPR_INFO, "Finish sending requests.");
+  }
+
+  void CreateStub() {
+    ChannelArguments args;
+    response_generator_ = grpc_fake_resolver_response_generator_create();
+    args.SetPointer(GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR,
+                    response_generator_);
+    std::ostringstream uri;
+    uri << "fake:///servername_not_used";
+    channel_ =
+        CreateCustomChannel(uri.str(), InsecureChannelCredentials(), args);
+    stub_ = grpc::testing::EchoTestService::NewStub(channel_);
+  }
+
+  void Start() {
+    // Start the backends.
+    std::vector<int> backend_ports;
+    for (size_t i = 0; i < kNumBackends; ++i) {
+      backends_.emplace_back(new BackendServiceImpl());
+      backend_servers_.emplace_back(ServerThread<BackendServiceImpl>(
+          "backend", server_host_, backends_.back().get()));
+      backend_ports.push_back(backend_servers_.back().port_);
+    }
+    // Start the load balancers.
+    for (size_t i = 0; i < kNumBalancers; ++i) {
+      balancers_.emplace_back(new BalancerServiceImpl(backend_ports));
+      balancer_servers_.emplace_back(ServerThread<BalancerServiceImpl>(
+          "balancer", server_host_, balancers_.back().get()));
+    }
+    // Start sending RPCs in multiple threads.
+    CreateStub();
+    for (size_t i = 0; i < kNumClientThreads; ++i) {
+      client_threads_.emplace_back(
+          std::thread(&ClientChannelStressTest::KeepSendingRequests, this));
+    }
+  }
+
+  void Shutdown() {
+    shutdown_ = true;
+    for (size_t i = 0; i < client_threads_.size(); ++i) {
+      client_threads_[i].join();
+    }
+    for (size_t i = 0; i < balancers_.size(); ++i) {
+      balancers_[i]->Shutdown();
+      balancer_servers_[i].Shutdown();
+    }
+    for (size_t i = 0; i < backends_.size(); ++i) {
+      backend_servers_[i].Shutdown();
+    }
+    grpc_fake_resolver_response_generator_unref(response_generator_);
+  }
+
+  std::atomic_bool shutdown_{false};
+  const grpc::string server_host_ = "localhost";
+  std::shared_ptr<Channel> channel_;
+  std::unique_ptr<grpc::testing::EchoTestService::Stub> stub_;
+  std::mutex stub_mutex_;
+  std::vector<std::unique_ptr<BackendServiceImpl>> backends_;
+  std::vector<std::unique_ptr<BalancerServiceImpl>> balancers_;
+  std::vector<ServerThread<BackendServiceImpl>> backend_servers_;
+  std::vector<ServerThread<BalancerServiceImpl>> balancer_servers_;
+  grpc_fake_resolver_response_generator* response_generator_;
+  std::vector<std::thread> client_threads_;
+};
+
+}  // namespace
+}  // namespace testing
+}  // namespace grpc
+
+int main(int argc, char** argv) {
+  grpc_init();
+  grpc_test_init(argc, argv);
+  grpc::testing::ClientChannelStressTest test;
+  test.Run();
+  grpc_shutdown();
+  return 0;
+}
diff --git a/test/cpp/codegen/proto_utils_test.cc b/test/cpp/codegen/proto_utils_test.cc
index fd05c90e9d..cc355bb24a 100644
--- a/test/cpp/codegen/proto_utils_test.cc
+++ b/test/cpp/codegen/proto_utils_test.cc
@@ -16,15 +16,16 @@
  *
  */
 
+#include <grpc++/impl/codegen/grpc_library.h>
 #include <grpc++/impl/codegen/proto_utils.h>
 #include <grpc++/impl/grpc_library.h>
+#include <grpc/impl/codegen/byte_buffer.h>
+#include <grpc/slice.h>
 #include <gtest/gtest.h>
 
 namespace grpc {
 namespace internal {
 
-static GrpcLibraryInitializer g_gli_initializer;
-
 // Provide access to GrpcBufferWriter internals.
 class GrpcBufferWriterPeer {
  public:
@@ -44,35 +45,120 @@ class ProtoUtilsTest : public ::testing::Test {};
 // GrpcBufferWriter Next()/Backup() invocations could result in a dangling
 // pointer returned by Next() due to the interaction between grpc_slice inlining
 // and GRPC_SLICE_START_PTR.
-TEST_F(ProtoUtilsTest, BackupNext) {
-  // Ensure the GrpcBufferWriter internals are initialized.
-  g_gli_initializer.summon();
-
+TEST_F(ProtoUtilsTest, TinyBackupThenNext) {
   grpc_byte_buffer* bp;
-  GrpcBufferWriter writer(&bp, 8192);
+  const int block_size = 1024;
+  GrpcBufferWriter writer(&bp, block_size, 8192);
   GrpcBufferWriterPeer peer(&writer);
 
   void* data;
   int size;
   // Allocate a slice.
   ASSERT_TRUE(writer.Next(&data, &size));
-  EXPECT_EQ(8192, size);
-  // Return a single byte. Before the fix that this test acts as a regression
-  // for, this would have resulted in an inlined backup slice.
+  EXPECT_EQ(block_size, size);
+  // Return a single byte.
   writer.BackUp(1);
-  EXPECT_TRUE(!peer.have_backup());
-  // On the next allocation, the slice is non-inlined.
+  EXPECT_FALSE(peer.have_backup());
+  // On the next allocation, the returned slice is non-inlined.
   ASSERT_TRUE(writer.Next(&data, &size));
-  EXPECT_TRUE(peer.slice().refcount != NULL);
+  EXPECT_TRUE(peer.slice().refcount != nullptr);
+  EXPECT_EQ(block_size, size);
 
   // Cleanup.
   g_core_codegen_interface->grpc_byte_buffer_destroy(bp);
 }
 
+namespace {
+
+// Set backup_size to 0 to indicate no backup is needed.
+void BufferWriterTest(int block_size, int total_size, int backup_size) {
+  grpc_byte_buffer* bp;
+  GrpcBufferWriter writer(&bp, block_size, total_size);
+
+  int written_size = 0;
+  void* data;
+  int size = 0;
+  bool backed_up_entire_slice = false;
+
+  while (written_size < total_size) {
+    EXPECT_TRUE(writer.Next(&data, &size));
+    EXPECT_GT(size, 0);
+    EXPECT_TRUE(data);
+    int write_size = size;
+    bool should_backup = false;
+    if (backup_size > 0 && size > backup_size) {
+      write_size = size - backup_size;
+      should_backup = true;
+    } else if (size == backup_size && !backed_up_entire_slice) {
+      // only backup entire slice once.
+      backed_up_entire_slice = true;
+      should_backup = true;
+      write_size = 0;
+    }
+    // May need a last backup.
+    if (write_size + written_size > total_size) {
+      write_size = total_size - written_size;
+      should_backup = true;
+      backup_size = size - write_size;
+      ASSERT_GT(backup_size, 0);
+    }
+    for (int i = 0; i < write_size; i++) {
+      ((uint8_t*)data)[i] = written_size % 128;
+      written_size++;
+    }
+    if (should_backup) {
+      writer.BackUp(backup_size);
+    }
+  }
+  EXPECT_EQ(grpc_byte_buffer_length(bp), (size_t)total_size);
+
+  grpc_byte_buffer_reader reader;
+  grpc_byte_buffer_reader_init(&reader, bp);
+  int read_bytes = 0;
+  while (read_bytes < total_size) {
+    grpc_slice s;
+    EXPECT_TRUE(grpc_byte_buffer_reader_next(&reader, &s));
+    for (size_t i = 0; i < GRPC_SLICE_LENGTH(s); i++) {
+      EXPECT_EQ(GRPC_SLICE_START_PTR(s)[i], read_bytes % 128);
+      read_bytes++;
+    }
+    grpc_slice_unref(s);
+  }
+  EXPECT_EQ(read_bytes, total_size);
+  grpc_byte_buffer_reader_destroy(&reader);
+  grpc_byte_buffer_destroy(bp);
+}
+
+TEST(WriterTest, TinyBlockTinyBackup) {
+  for (int i = 2; i < (int)GRPC_SLICE_INLINED_SIZE; i++) {
+    BufferWriterTest(i, 256, 1);
+  }
+}
+
+TEST(WriterTest, SmallBlockTinyBackup) { BufferWriterTest(64, 256, 1); }
+
+TEST(WriterTest, SmallBlockNoBackup) { BufferWriterTest(64, 256, 0); }
+
+TEST(WriterTest, SmallBlockFullBackup) { BufferWriterTest(64, 256, 64); }
+
+TEST(WriterTest, LargeBlockTinyBackup) { BufferWriterTest(4096, 8192, 1); }
+
+TEST(WriterTest, LargeBlockNoBackup) { BufferWriterTest(4096, 8192, 0); }
+
+TEST(WriterTest, LargeBlockFullBackup) { BufferWriterTest(4096, 8192, 4096); }
+
+TEST(WriterTest, LargeBlockLargeBackup) { BufferWriterTest(4096, 8192, 4095); }
+
+}  // namespace
 }  // namespace internal
 }  // namespace grpc
 
 int main(int argc, char** argv) {
+  // Ensure the GrpcBufferWriter internals are initialized.
+  grpc::internal::GrpcLibraryInitializer init;
+  init.summon();
+  grpc::GrpcLibraryCodegen lib;
+
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();
 }
diff --git a/test/cpp/common/auth_property_iterator_test.cc b/test/cpp/common/auth_property_iterator_test.cc
index 4a097e8739..fce409aa2f 100644
--- a/test/cpp/common/auth_property_iterator_test.cc
+++ b/test/cpp/common/auth_property_iterator_test.cc
@@ -40,7 +40,7 @@ class TestAuthPropertyIterator : public AuthPropertyIterator {
 class AuthPropertyIteratorTest : public ::testing::Test {
  protected:
   void SetUp() override {
-    ctx_ = grpc_auth_context_create(NULL);
+    ctx_ = grpc_auth_context_create(nullptr);
     grpc_auth_context_add_cstring_property(ctx_, "name", "chapi");
     grpc_auth_context_add_cstring_property(ctx_, "name", "chapo");
     grpc_auth_context_add_cstring_property(ctx_, "foo", "bar");
diff --git a/test/cpp/common/secure_auth_context_test.cc b/test/cpp/common/secure_auth_context_test.cc
index 0cc32c1853..7a0530c20a 100644
--- a/test/cpp/common/secure_auth_context_test.cc
+++ b/test/cpp/common/secure_auth_context_test.cc
@@ -42,7 +42,7 @@ TEST_F(SecureAuthContextTest, EmptyContext) {
 }
 
 TEST_F(SecureAuthContextTest, Properties) {
-  grpc_auth_context* ctx = grpc_auth_context_create(NULL);
+  grpc_auth_context* ctx = grpc_auth_context_create(nullptr);
   SecureAuthContext context(ctx, true);
   context.AddProperty("name", "chapi");
   context.AddProperty("name", "chapo");
@@ -60,7 +60,7 @@ TEST_F(SecureAuthContextTest, Properties) {
 }
 
 TEST_F(SecureAuthContextTest, Iterators) {
-  grpc_auth_context* ctx = grpc_auth_context_create(NULL);
+  grpc_auth_context* ctx = grpc_auth_context_create(nullptr);
   SecureAuthContext context(ctx, true);
   context.AddProperty("name", "chapi");
   context.AddProperty("name", "chapo");
diff --git a/test/cpp/end2end/async_end2end_test.cc b/test/cpp/end2end/async_end2end_test.cc
index 5b6e9aa312..1ea087e706 100644
--- a/test/cpp/end2end/async_end2end_test.cc
+++ b/test/cpp/end2end/async_end2end_test.cc
@@ -466,7 +466,7 @@ TEST_P(AsyncEnd2endTest, ReconnectChannel) {
   // It needs 2 pollset_works to reconnect the channel with polling engine
   // "poll"
   char* s = gpr_getenv("GRPC_POLL_STRATEGY");
-  if (s != NULL && 0 == strcmp(s, "poll")) {
+  if (s != nullptr && 0 == strcmp(s, "poll")) {
     poller_slowdown_factor = 2;
   }
   gpr_free(s);
diff --git a/test/cpp/end2end/client_lb_end2end_test.cc b/test/cpp/end2end/client_lb_end2end_test.cc
index 95630a7714..f8bb12fde1 100644
--- a/test/cpp/end2end/client_lb_end2end_test.cc
+++ b/test/cpp/end2end/client_lb_end2end_test.cc
@@ -113,22 +113,23 @@ class ClientLbEnd2endTest : public ::testing::Test {
 
   void SetNextResolution(const std::vector<int>& ports) {
     grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-    grpc_lb_addresses* addresses = grpc_lb_addresses_create(ports.size(), NULL);
+    grpc_lb_addresses* addresses =
+        grpc_lb_addresses_create(ports.size(), nullptr);
     for (size_t i = 0; i < ports.size(); ++i) {
       char* lb_uri_str;
       gpr_asprintf(&lb_uri_str, "ipv4:127.0.0.1:%d", ports[i]);
       grpc_uri* lb_uri = grpc_uri_parse(&exec_ctx, lb_uri_str, true);
-      GPR_ASSERT(lb_uri != NULL);
+      GPR_ASSERT(lb_uri != nullptr);
       grpc_lb_addresses_set_address_from_uri(addresses, i, lb_uri,
                                              false /* is balancer */,
-                                             "" /* balancer name */, NULL);
+                                             "" /* balancer name */, nullptr);
       grpc_uri_destroy(lb_uri);
       gpr_free(lb_uri_str);
     }
     const grpc_arg fake_addresses =
         grpc_lb_addresses_create_channel_arg(addresses);
     grpc_channel_args* fake_result =
-        grpc_channel_args_copy_and_add(NULL, &fake_addresses, 1);
+        grpc_channel_args_copy_and_add(nullptr, &fake_addresses, 1);
     grpc_fake_resolver_response_generator_set_response(
         &exec_ctx, response_generator_, fake_result);
     grpc_channel_args_destroy(&exec_ctx, fake_result);
diff --git a/test/cpp/end2end/end2end_test.cc b/test/cpp/end2end/end2end_test.cc
index 82ca39466e..c71034bbe8 100644
--- a/test/cpp/end2end/end2end_test.cc
+++ b/test/cpp/end2end/end2end_test.cc
@@ -711,7 +711,7 @@ TEST_P(End2endTest, ReconnectChannel) {
   // It needs 2 pollset_works to reconnect the channel with polling engine
   // "poll"
   char* s = gpr_getenv("GRPC_POLL_STRATEGY");
-  if (s != NULL && 0 == strcmp(s, "poll")) {
+  if (s != nullptr && 0 == strcmp(s, "poll")) {
     poller_slowdown_factor = 2;
   }
   gpr_free(s);
@@ -1148,7 +1148,7 @@ TEST_P(End2endTest, ChannelState) {
   CompletionQueue cq;
   std::chrono::system_clock::time_point deadline =
       std::chrono::system_clock::now() + std::chrono::milliseconds(10);
-  channel_->NotifyOnStateChange(GRPC_CHANNEL_IDLE, deadline, &cq, NULL);
+  channel_->NotifyOnStateChange(GRPC_CHANNEL_IDLE, deadline, &cq, nullptr);
   void* tag;
   bool ok = true;
   cq.Next(&tag, &ok);
diff --git a/test/cpp/end2end/grpclb_end2end_test.cc b/test/cpp/end2end/grpclb_end2end_test.cc
index c15ab88da1..bbf3da4663 100644
--- a/test/cpp/end2end/grpclb_end2end_test.cc
+++ b/test/cpp/end2end/grpclb_end2end_test.cc
@@ -353,11 +353,6 @@ class GrpclbEnd2endTest : public ::testing::Test {
           "balancer", server_host_, balancers_.back().get()));
     }
     ResetStub();
-    std::vector<AddressData> addresses;
-    for (size_t i = 0; i < balancer_servers_.size(); ++i) {
-      addresses.emplace_back(AddressData{balancer_servers_[i].port_, true, ""});
-    }
-    SetNextResolution(addresses);
   }
 
   void TearDown() override {
@@ -370,6 +365,14 @@ class GrpclbEnd2endTest : public ::testing::Test {
     grpc_fake_resolver_response_generator_unref(response_generator_);
   }
 
+  void SetNextResolutionAllBalancers() {
+    std::vector<AddressData> addresses;
+    for (size_t i = 0; i < balancer_servers_.size(); ++i) {
+      addresses.emplace_back(AddressData{balancer_servers_[i].port_, true, ""});
+    }
+    SetNextResolution(addresses);
+  }
+
   void ResetStub(int fallback_timeout = 0) {
     ChannelArguments args;
     args.SetGrpclbFallbackTimeout(fallback_timeout);
@@ -581,6 +584,7 @@ class SingleBalancerTest : public GrpclbEnd2endTest {
 };
 
 TEST_F(SingleBalancerTest, Vanilla) {
+  SetNextResolutionAllBalancers();
   const size_t kNumRpcsPerAddress = 100;
   ScheduleResponseForBalancer(
       0, BalancerServiceImpl::BuildResponseForBackends(GetBackendPorts(), {}),
@@ -608,6 +612,7 @@ TEST_F(SingleBalancerTest, Vanilla) {
 }
 
 TEST_F(SingleBalancerTest, InitiallyEmptyServerlist) {
+  SetNextResolutionAllBalancers();
   const int kServerlistDelayMs = 500 * grpc_test_slowdown_factor();
   const int kCallDeadlineMs = 1000 * grpc_test_slowdown_factor();
 
@@ -645,6 +650,7 @@ TEST_F(SingleBalancerTest, InitiallyEmptyServerlist) {
 }
 
 TEST_F(SingleBalancerTest, Fallback) {
+  SetNextResolutionAllBalancers();
   const int kFallbackTimeoutMs = 200 * grpc_test_slowdown_factor();
   const int kServerlistDelayMs = 500 * grpc_test_slowdown_factor();
   const size_t kNumBackendInResolution = backends_.size() / 2;
@@ -711,6 +717,7 @@ TEST_F(SingleBalancerTest, Fallback) {
 }
 
 TEST_F(SingleBalancerTest, FallbackUpdate) {
+  SetNextResolutionAllBalancers();
   const int kFallbackTimeoutMs = 200 * grpc_test_slowdown_factor();
   const int kServerlistDelayMs = 500 * grpc_test_slowdown_factor();
   const size_t kNumBackendInResolution = backends_.size() / 3;
@@ -818,6 +825,7 @@ TEST_F(SingleBalancerTest, FallbackUpdate) {
 }
 
 TEST_F(SingleBalancerTest, BackendsRestart) {
+  SetNextResolutionAllBalancers();
   const size_t kNumRpcsPerAddress = 100;
   ScheduleResponseForBalancer(
       0, BalancerServiceImpl::BuildResponseForBackends(GetBackendPorts(), {}),
@@ -857,6 +865,7 @@ class UpdatesTest : public GrpclbEnd2endTest {
 };
 
 TEST_F(UpdatesTest, UpdateBalancers) {
+  SetNextResolutionAllBalancers();
   const std::vector<int> first_backend{GetBackendPorts()[0]};
   const std::vector<int> second_backend{GetBackendPorts()[1]};
   ScheduleResponseForBalancer(
@@ -919,6 +928,7 @@ TEST_F(UpdatesTest, UpdateBalancers) {
 // verify that the LB channel inside grpclb keeps the initial connection (which
 // by definition is also present in the update).
 TEST_F(UpdatesTest, UpdateBalancersRepeated) {
+  SetNextResolutionAllBalancers();
   const std::vector<int> first_backend{GetBackendPorts()[0]};
   const std::vector<int> second_backend{GetBackendPorts()[0]};
 
@@ -989,6 +999,9 @@ TEST_F(UpdatesTest, UpdateBalancersRepeated) {
 }
 
 TEST_F(UpdatesTest, UpdateBalancersDeadUpdate) {
+  std::vector<AddressData> addresses;
+  addresses.emplace_back(AddressData{balancer_servers_[0].port_, true, ""});
+  SetNextResolution(addresses);
   const std::vector<int> first_backend{GetBackendPorts()[0]};
   const std::vector<int> second_backend{GetBackendPorts()[1]};
 
@@ -1030,7 +1043,7 @@ TEST_F(UpdatesTest, UpdateBalancersDeadUpdate) {
   EXPECT_EQ(0U, balancer_servers_[2].service_->request_count());
   EXPECT_EQ(0U, balancer_servers_[2].service_->response_count());
 
-  std::vector<AddressData> addresses;
+  addresses.clear();
   addresses.emplace_back(AddressData{balancer_servers_[1].port_, true, ""});
   gpr_log(GPR_INFO, "========= ABOUT TO UPDATE 1 ==========");
   SetNextResolution(addresses);
@@ -1055,8 +1068,14 @@ TEST_F(UpdatesTest, UpdateBalancersDeadUpdate) {
   balancers_[2]->NotifyDoneWithServerlists();
   EXPECT_EQ(1U, balancer_servers_[0].service_->request_count());
   EXPECT_EQ(1U, balancer_servers_[0].service_->response_count());
-  EXPECT_EQ(1U, balancer_servers_[1].service_->request_count());
-  EXPECT_EQ(1U, balancer_servers_[1].service_->response_count());
+  // The second balancer, published as part of the first update, may end up
+  // getting two requests (that is, 1 <= #req <= 2) if the LB call retry timer
+  // firing races with the arrival of the update containing the second
+  // balancer.
+  EXPECT_GE(balancer_servers_[1].service_->request_count(), 1U);
+  EXPECT_GE(balancer_servers_[1].service_->response_count(), 1U);
+  EXPECT_LE(balancer_servers_[1].service_->request_count(), 2U);
+  EXPECT_LE(balancer_servers_[1].service_->response_count(), 2U);
   EXPECT_EQ(0U, balancer_servers_[2].service_->request_count());
   EXPECT_EQ(0U, balancer_servers_[2].service_->response_count());
   // Check LB policy name for the channel.
@@ -1064,6 +1083,7 @@ TEST_F(UpdatesTest, UpdateBalancersDeadUpdate) {
 }
 
 TEST_F(SingleBalancerTest, Drop) {
+  SetNextResolutionAllBalancers();
   const size_t kNumRpcsPerAddress = 100;
   const int num_of_drop_by_rate_limiting_addresses = 1;
   const int num_of_drop_by_load_balancing_addresses = 2;
@@ -1107,6 +1127,7 @@ TEST_F(SingleBalancerTest, Drop) {
 }
 
 TEST_F(SingleBalancerTest, DropAllFirst) {
+  SetNextResolutionAllBalancers();
   // All registered addresses are marked as "drop".
   const int num_of_drop_by_rate_limiting_addresses = 1;
   const int num_of_drop_by_load_balancing_addresses = 1;
@@ -1122,6 +1143,7 @@ TEST_F(SingleBalancerTest, DropAllFirst) {
 }
 
 TEST_F(SingleBalancerTest, DropAll) {
+  SetNextResolutionAllBalancers();
   ScheduleResponseForBalancer(
       0, BalancerServiceImpl::BuildResponseForBackends(GetBackendPorts(), {}),
       0);
@@ -1152,6 +1174,7 @@ class SingleBalancerWithClientLoadReportingTest : public GrpclbEnd2endTest {
 };
 
 TEST_F(SingleBalancerWithClientLoadReportingTest, Vanilla) {
+  SetNextResolutionAllBalancers();
   const size_t kNumRpcsPerAddress = 100;
   ScheduleResponseForBalancer(
       0, BalancerServiceImpl::BuildResponseForBackends(GetBackendPorts(), {}),
@@ -1186,6 +1209,7 @@ TEST_F(SingleBalancerWithClientLoadReportingTest, Vanilla) {
 }
 
 TEST_F(SingleBalancerWithClientLoadReportingTest, Drop) {
+  SetNextResolutionAllBalancers();
   const size_t kNumRpcsPerAddress = 3;
   const int num_of_drop_by_rate_limiting_addresses = 2;
   const int num_of_drop_by_load_balancing_addresses = 1;
diff --git a/test/cpp/grpclb/grpclb_api_test.cc b/test/cpp/grpclb/grpclb_api_test.cc
index 54b5708e6a..03778e1fc5 100644
--- a/test/cpp/grpclb/grpclb_api_test.cc
+++ b/test/cpp/grpclb/grpclb_api_test.cc
@@ -48,7 +48,7 @@ grpc::string PackedStringToIp(const grpc_grpclb_ip_address& pb_ip) {
   } else {
     abort();
   }
-  GPR_ASSERT(inet_ntop(af, (void*)pb_ip.bytes, ip_str, 46) != NULL);
+  GPR_ASSERT(inet_ntop(af, (void*)pb_ip.bytes, ip_str, 46) != nullptr);
   return ip_str;
 }
 
diff --git a/test/cpp/grpclb/grpclb_test.cc b/test/cpp/grpclb/grpclb_test.cc
index d032c0dfcc..62ae495177 100644
--- a/test/cpp/grpclb/grpclb_test.cc
+++ b/test/cpp/grpclb/grpclb_test.cc
@@ -149,7 +149,7 @@ static void drain_cq(grpc_completion_queue* cq) {
   grpc_event ev;
   do {
     ev = grpc_completion_queue_next(cq, grpc_timeout_seconds_to_deadline(5),
-                                    NULL);
+                                    nullptr);
   } while (ev.type != GRPC_QUEUE_SHUTDOWN);
 }
 
@@ -188,16 +188,16 @@ static void start_lb_server(server_fixture* sf, int* ports, size_t nports,
 
   // make sure we've received the initial metadata from the grpclb request.
   GPR_ASSERT(request_metadata_recv.count > 0);
-  GPR_ASSERT(request_metadata_recv.metadata != NULL);
+  GPR_ASSERT(request_metadata_recv.metadata != nullptr);
 
   // receive request for backends
   op = ops;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message.recv_message = &request_payload_recv;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
-  error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(202), NULL);
+  error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(202), nullptr);
   GPR_ASSERT(GRPC_CALL_OK == error);
   CQ_EXPECT_COMPLETION(cqv, tag(202), 1);
   cq_verify(cqv);
@@ -222,14 +222,14 @@ static void start_lb_server(server_fixture* sf, int* ports, size_t nports,
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
-  error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(201), NULL);
+  error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(201), nullptr);
   GPR_ASSERT(GRPC_CALL_OK == error);
   gpr_log(GPR_INFO, "LB Server[%s](%s) after tag 201", sf->servers_hostport,
           sf->balancer_name);
@@ -252,9 +252,10 @@ static void start_lb_server(server_fixture* sf, int* ports, size_t nports,
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message.send_message = response_payload;
     op->flags = 0;
-    op->reserved = NULL;
+    op->reserved = nullptr;
     op++;
-    error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(203), NULL);
+    error =
+        grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(203), nullptr);
     GPR_ASSERT(GRPC_CALL_OK == error);
     CQ_EXPECT_COMPLETION(cqv, tag(203), 1);
     cq_verify(cqv);
@@ -274,9 +275,9 @@ static void start_lb_server(server_fixture* sf, int* ports, size_t nports,
   grpc_slice status_details = grpc_slice_from_static_string("xyz");
   op->data.send_status_from_server.status_details = &status_details;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
-  error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(204), NULL);
+  error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(204), nullptr);
   GPR_ASSERT(GRPC_CALL_OK == error);
 
   CQ_EXPECT_COMPLETION(cqv, tag(201), 1);
@@ -318,8 +319,8 @@ static void start_backend_server(server_fixture* sf) {
                                      tag(100));
     GPR_ASSERT(GRPC_CALL_OK == error);
     gpr_log(GPR_INFO, "Server[%s] up", sf->servers_hostport);
-    ev = grpc_completion_queue_next(sf->cq,
-                                    grpc_timeout_seconds_to_deadline(60), NULL);
+    ev = grpc_completion_queue_next(
+        sf->cq, grpc_timeout_seconds_to_deadline(60), nullptr);
     if (!ev.success) {
       gpr_log(GPR_INFO, "Server[%s] being torn down", sf->servers_hostport);
       cq_verifier_destroy(cqv);
@@ -341,14 +342,15 @@ static void start_backend_server(server_fixture* sf) {
     op->op = GRPC_OP_SEND_INITIAL_METADATA;
     op->data.send_initial_metadata.count = 0;
     op->flags = 0;
-    op->reserved = NULL;
+    op->reserved = nullptr;
     op++;
     op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
     op->data.recv_close_on_server.cancelled = &was_cancelled;
     op->flags = 0;
-    op->reserved = NULL;
+    op->reserved = nullptr;
     op++;
-    error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(101), NULL);
+    error =
+        grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(101), nullptr);
     GPR_ASSERT(GRPC_CALL_OK == error);
     gpr_log(GPR_INFO, "Server[%s] after tag 101", sf->servers_hostport);
 
@@ -359,15 +361,16 @@ static void start_backend_server(server_fixture* sf) {
       op->op = GRPC_OP_RECV_MESSAGE;
       op->data.recv_message.recv_message = &request_payload_recv;
       op->flags = 0;
-      op->reserved = NULL;
+      op->reserved = nullptr;
       op++;
-      error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(102), NULL);
+      error =
+          grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(102), nullptr);
       GPR_ASSERT(GRPC_CALL_OK == error);
       ev = grpc_completion_queue_next(
-          sf->cq, grpc_timeout_seconds_to_deadline(3), NULL);
+          sf->cq, grpc_timeout_seconds_to_deadline(3), nullptr);
       if (ev.type == GRPC_OP_COMPLETE && ev.success) {
         GPR_ASSERT(ev.tag = tag(102));
-        if (request_payload_recv == NULL) {
+        if (request_payload_recv == nullptr) {
           exit = true;
           gpr_log(GPR_INFO,
                   "Server[%s] recv \"close\" from client, exiting. Call #%d",
@@ -388,13 +391,13 @@ static void start_backend_server(server_fixture* sf) {
         op->op = GRPC_OP_SEND_MESSAGE;
         op->data.send_message.send_message = response_payload;
         op->flags = 0;
-        op->reserved = NULL;
+        op->reserved = nullptr;
         op++;
-        error =
-            grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(103), NULL);
+        error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(103),
+                                      nullptr);
         GPR_ASSERT(GRPC_CALL_OK == error);
         ev = grpc_completion_queue_next(
-            sf->cq, grpc_timeout_seconds_to_deadline(3), NULL);
+            sf->cq, grpc_timeout_seconds_to_deadline(3), nullptr);
         if (ev.type == GRPC_OP_COMPLETE && ev.success) {
           GPR_ASSERT(ev.tag = tag(103));
         } else {
@@ -422,9 +425,10 @@ static void start_backend_server(server_fixture* sf) {
         grpc_slice_from_static_string("Backend server out a-ok");
     op->data.send_status_from_server.status_details = &status_details;
     op->flags = 0;
-    op->reserved = NULL;
+    op->reserved = nullptr;
     op++;
-    error = grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(104), NULL);
+    error =
+        grpc_call_start_batch(s, ops, (size_t)(op - ops), tag(104), nullptr);
     GPR_ASSERT(GRPC_CALL_OK == error);
 
     CQ_EXPECT_COMPLETION(cqv, tag(101), 1);
@@ -459,10 +463,10 @@ static void perform_request(client_fixture* cf) {
       grpc_slice_from_copied_string("hello world");
 
   grpc_slice host = grpc_slice_from_static_string("foo.test.google.fr:1234");
-  c = grpc_channel_create_call(cf->client, NULL, GRPC_PROPAGATE_DEFAULTS,
+  c = grpc_channel_create_call(cf->client, nullptr, GRPC_PROPAGATE_DEFAULTS,
                                cf->cq, grpc_slice_from_static_string("/foo"),
                                &host, grpc_timeout_seconds_to_deadline(5),
-                               NULL);
+                               nullptr);
   gpr_log(GPR_INFO, "Call 0x%" PRIxPTR " created", (intptr_t)c);
   GPR_ASSERT(c);
   char* peer;
@@ -474,21 +478,21 @@ static void perform_request(client_fixture* cf) {
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
   op->data.recv_status_on_client.status = &status;
   op->data.recv_status_on_client.status_details = &details;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
-  error = grpc_call_start_batch(c, ops, (size_t)(op - ops), tag(1), NULL);
+  error = grpc_call_start_batch(c, ops, (size_t)(op - ops), tag(1), nullptr);
   GPR_ASSERT(GRPC_CALL_OK == error);
 
   for (i = 0; i < 4; i++) {
@@ -498,14 +502,14 @@ static void perform_request(client_fixture* cf) {
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message.send_message = request_payload;
     op->flags = 0;
-    op->reserved = NULL;
+    op->reserved = nullptr;
     op++;
     op->op = GRPC_OP_RECV_MESSAGE;
     op->data.recv_message.recv_message = &response_payload_recv;
     op->flags = 0;
-    op->reserved = NULL;
+    op->reserved = nullptr;
     op++;
-    error = grpc_call_start_batch(c, ops, (size_t)(op - ops), tag(2), NULL);
+    error = grpc_call_start_batch(c, ops, (size_t)(op - ops), tag(2), nullptr);
     GPR_ASSERT(GRPC_CALL_OK == error);
 
     CQ_EXPECT_COMPLETION(cqv, tag(2), 1);
@@ -522,9 +526,9 @@ static void perform_request(client_fixture* cf) {
   op = ops;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
-  op->reserved = NULL;
+  op->reserved = nullptr;
   op++;
-  error = grpc_call_start_batch(c, ops, (size_t)(op - ops), tag(3), NULL);
+  error = grpc_call_start_batch(c, ops, (size_t)(op - ops), tag(3), nullptr);
   GPR_ASSERT(GRPC_CALL_OK == error);
 
   CQ_EXPECT_COMPLETION(cqv, tag(1), 1);
@@ -550,20 +554,20 @@ static void setup_client(const server_fixture* lb_server,
                          const server_fixture* backends, client_fixture* cf) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
 
-  char* expected_target_names = NULL;
+  char* expected_target_names = nullptr;
   const char* backends_name = lb_server->servers_hostport;
   gpr_asprintf(&expected_target_names, "%s;%s", backends_name, BALANCERS_NAME);
 
   grpc_fake_resolver_response_generator* response_generator =
       grpc_fake_resolver_response_generator_create();
 
-  grpc_lb_addresses* addresses = grpc_lb_addresses_create(1, NULL);
+  grpc_lb_addresses* addresses = grpc_lb_addresses_create(1, nullptr);
   char* lb_uri_str;
   gpr_asprintf(&lb_uri_str, "ipv4:%s", lb_server->servers_hostport);
   grpc_uri* lb_uri = grpc_uri_parse(&exec_ctx, lb_uri_str, true);
-  GPR_ASSERT(lb_uri != NULL);
+  GPR_ASSERT(lb_uri != nullptr);
   grpc_lb_addresses_set_address_from_uri(addresses, 0, lb_uri, true,
-                                         lb_server->balancer_name, NULL);
+                                         lb_server->balancer_name, nullptr);
   grpc_uri_destroy(lb_uri);
   gpr_free(lb_uri_str);
 
@@ -571,22 +575,22 @@ static void setup_client(const server_fixture* lb_server,
   const grpc_arg fake_addresses =
       grpc_lb_addresses_create_channel_arg(addresses);
   grpc_channel_args* fake_result =
-      grpc_channel_args_copy_and_add(NULL, &fake_addresses, 1);
+      grpc_channel_args_copy_and_add(nullptr, &fake_addresses, 1);
   grpc_lb_addresses_destroy(&exec_ctx, addresses);
 
   const grpc_arg new_args[] = {
       grpc_fake_transport_expected_targets_arg(expected_target_names),
       grpc_fake_resolver_response_generator_arg(response_generator)};
 
-  grpc_channel_args* args =
-      grpc_channel_args_copy_and_add(NULL, new_args, GPR_ARRAY_SIZE(new_args));
+  grpc_channel_args* args = grpc_channel_args_copy_and_add(
+      nullptr, new_args, GPR_ARRAY_SIZE(new_args));
   gpr_free(expected_target_names);
 
-  cf->cq = grpc_completion_queue_create_for_next(NULL);
+  cf->cq = grpc_completion_queue_create_for_next(nullptr);
   grpc_channel_credentials* fake_creds =
       grpc_fake_transport_security_credentials_create();
   cf->client =
-      grpc_secure_channel_create(fake_creds, cf->server_uri, args, NULL);
+      grpc_secure_channel_create(fake_creds, cf->server_uri, args, nullptr);
   grpc_fake_resolver_response_generator_set_response(
       &exec_ctx, response_generator, fake_result);
   grpc_channel_args_destroy(&exec_ctx, fake_result);
@@ -600,16 +604,16 @@ static void teardown_client(client_fixture* cf) {
   grpc_completion_queue_shutdown(cf->cq);
   drain_cq(cf->cq);
   grpc_completion_queue_destroy(cf->cq);
-  cf->cq = NULL;
+  cf->cq = nullptr;
   grpc_channel_destroy(cf->client);
-  cf->client = NULL;
+  cf->client = nullptr;
   gpr_free(cf->server_uri);
 }
 
 static void setup_server(const char* host, server_fixture* sf) {
   int assigned_port;
 
-  sf->cq = grpc_completion_queue_create_for_next(NULL);
+  sf->cq = grpc_completion_queue_create_for_next(nullptr);
   const char* colon_idx = strchr(host, ':');
   if (colon_idx) {
     const char* port_str = colon_idx + 1;
@@ -623,8 +627,8 @@ static void setup_server(const char* host, server_fixture* sf) {
   grpc_server_credentials* server_creds =
       grpc_fake_transport_security_server_credentials_create();
 
-  sf->server = grpc_server_create(NULL, NULL);
-  grpc_server_register_completion_queue(sf->server, sf->cq, NULL);
+  sf->server = grpc_server_create(nullptr, nullptr);
+  grpc_server_register_completion_queue(sf->server, sf->cq, nullptr);
   GPR_ASSERT((assigned_port = grpc_server_add_secure_http2_port(
                   sf->server, sf->servers_hostport, server_creds)) > 0);
   grpc_server_credentials_release(server_creds);
@@ -638,17 +642,17 @@ static void teardown_server(server_fixture* sf) {
   gpr_log(GPR_INFO, "Server[%s] shutting down", sf->servers_hostport);
 
   grpc_completion_queue* shutdown_cq =
-      grpc_completion_queue_create_for_pluck(NULL);
+      grpc_completion_queue_create_for_pluck(nullptr);
   grpc_server_shutdown_and_notify(sf->server, shutdown_cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(shutdown_cq, tag(1000),
                                          grpc_timeout_seconds_to_deadline(5),
-                                         NULL)
+                                         nullptr)
                  .type == GRPC_OP_COMPLETE);
   grpc_completion_queue_destroy(shutdown_cq);
   grpc_server_destroy(sf->server);
   gpr_thd_join(sf->tid);
 
-  sf->server = NULL;
+  sf->server = nullptr;
   grpc_completion_queue_shutdown(sf->cq);
   drain_cq(sf->cq);
   grpc_completion_queue_destroy(sf->cq);
@@ -689,14 +693,15 @@ static test_fixture setup_test_fixture(int lb_server_update_delay_ms) {
       tf.lb_backends[i].lb_token_prefix = "";
     }
     setup_server("127.0.0.1", &tf.lb_backends[i]);
-    gpr_thd_new(&tf.lb_backends[i].tid, fork_backend_server, &tf.lb_backends[i],
-                &options);
+    gpr_thd_new(&tf.lb_backends[i].tid, "grpclb_backend", fork_backend_server,
+                &tf.lb_backends[i], &options);
   }
 
   tf.lb_server.lb_token_prefix = LB_TOKEN_PREFIX;
   tf.lb_server.balancer_name = BALANCERS_NAME;
   setup_server("127.0.0.1", &tf.lb_server);
-  gpr_thd_new(&tf.lb_server.tid, fork_lb_server, &tf.lb_server, &options);
+  gpr_thd_new(&tf.lb_server.tid, "grpclb_server", fork_lb_server, &tf.lb_server,
+              &options);
   setup_client(&tf.lb_server, tf.lb_backends, &tf.client);
   return tf;
 }
diff --git a/test/cpp/interop/http2_client.cc b/test/cpp/interop/http2_client.cc
index 1e04e57d09..2de7abcf17 100644
--- a/test/cpp/interop/http2_client.cc
+++ b/test/cpp/interop/http2_client.cc
@@ -217,7 +217,7 @@ int main(int argc, char** argv) {
         "goaway",         "max_streams",      "ping",
         "rst_after_data", "rst_after_header", "rst_during_data"};
     char* joined_testcases =
-        gpr_strjoin_sep(testcases, GPR_ARRAY_SIZE(testcases), "\n", NULL);
+        gpr_strjoin_sep(testcases, GPR_ARRAY_SIZE(testcases), "\n", nullptr);
 
     gpr_log(GPR_ERROR, "Unsupported test case %s. Valid options are\n%s",
             FLAGS_test_case.c_str(), joined_testcases);
diff --git a/test/cpp/interop/interop_server.cc b/test/cpp/interop/interop_server.cc
index a24cdc7d2d..30bd8bfef8 100644
--- a/test/cpp/interop/interop_server.cc
+++ b/test/cpp/interop/interop_server.cc
@@ -317,9 +317,15 @@ class TestServiceImpl : public TestService::Service {
 
 void grpc::testing::interop::RunServer(
     std::shared_ptr<ServerCredentials> creds) {
-  GPR_ASSERT(FLAGS_port != 0);
+  RunServer(creds, FLAGS_port, nullptr);
+}
+
+void grpc::testing::interop::RunServer(
+    std::shared_ptr<ServerCredentials> creds, const int port,
+    ServerStartedCondition* server_started_condition) {
+  GPR_ASSERT(port != 0);
   std::ostringstream server_address;
-  server_address << "0.0.0.0:" << FLAGS_port;
+  server_address << "0.0.0.0:" << port;
   TestServiceImpl service;
 
   SimpleRequest request;
@@ -333,6 +339,14 @@ void grpc::testing::interop::RunServer(
   }
   std::unique_ptr<Server> server(builder.BuildAndStart());
   gpr_log(GPR_INFO, "Server listening on %s", server_address.str().c_str());
+
+  // Signal that the server has started.
+  if (server_started_condition) {
+    std::unique_lock<std::mutex> lock(server_started_condition->mutex);
+    server_started_condition->server_started = true;
+    server_started_condition->condition.notify_all();
+  }
+
   while (!gpr_atm_no_barrier_load(&g_got_sigint)) {
     gpr_sleep_until(gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
                                  gpr_time_from_seconds(5, GPR_TIMESPAN)));
diff --git a/test/cpp/interop/server_helper.h b/test/cpp/interop/server_helper.h
index 6af003fe93..1bf7db1e14 100644
--- a/test/cpp/interop/server_helper.h
+++ b/test/cpp/interop/server_helper.h
@@ -19,6 +19,7 @@
 #ifndef GRPC_TEST_CPP_INTEROP_SERVER_HELPER_H
 #define GRPC_TEST_CPP_INTEROP_SERVER_HELPER_H
 
+#include <condition_variable>
 #include <memory>
 
 #include <grpc/compression.h>
@@ -50,8 +51,27 @@ class InteropServerContextInspector {
 namespace interop {
 
 extern gpr_atm g_got_sigint;
+
+struct ServerStartedCondition {
+  std::mutex mutex;
+  std::condition_variable condition;
+  bool server_started = false;
+};
+
+/// Run gRPC interop server using port FLAGS_port.
+///
+/// \param creds The credentials associated with the server.
 void RunServer(std::shared_ptr<ServerCredentials> creds);
 
+/// Run gRPC interop server.
+///
+/// \param creds The credentials associated with the server.
+/// \param port Port to use for the server.
+/// \param server_started_condition (optional) Struct holding mutex, condition
+///     variable, and condition used to notify when the server has started.
+void RunServer(std::shared_ptr<ServerCredentials> creds, int port,
+               ServerStartedCondition* server_started_condition);
+
 }  // namespace interop
 }  // namespace testing
 }  // namespace grpc
diff --git a/test/cpp/interop/stress_test.cc b/test/cpp/interop/stress_test.cc
index 991fc88ad2..4b39dc3211 100644
--- a/test/cpp/interop/stress_test.cc
+++ b/test/cpp/interop/stress_test.cc
@@ -36,9 +36,7 @@
 #include "test/cpp/util/metrics_server.h"
 #include "test/cpp/util/test_config.h"
 
-extern "C" {
 extern void gpr_default_log(gpr_log_func_args* args);
-}
 
 DEFINE_int32(metrics_port, 8081, "The metrics server port.");
 
@@ -230,7 +228,7 @@ int main(int argc, char** argv) {
   log_level = FLAGS_log_level;
   gpr_set_log_function(TestLogFunction);
 
-  srand(time(NULL));
+  srand(time(nullptr));
 
   // Parse the server addresses
   std::vector<grpc::string> server_addresses;
diff --git a/test/cpp/microbenchmarks/bm_call_create.cc b/test/cpp/microbenchmarks/bm_call_create.cc
index ec5c1275d1..a45c577320 100644
--- a/test/cpp/microbenchmarks/bm_call_create.cc
+++ b/test/cpp/microbenchmarks/bm_call_create.cc
@@ -91,7 +91,7 @@ class InsecureChannel : public BaseChannelFixture {
  public:
   InsecureChannel()
       : BaseChannelFixture(
-            grpc_insecure_channel_create("localhost:1234", NULL, NULL)) {}
+            grpc_insecure_channel_create("localhost:1234", nullptr, nullptr)) {}
 };
 
 class LameChannel : public BaseChannelFixture {
@@ -105,14 +105,14 @@ template <class Fixture>
 static void BM_CallCreateDestroy(benchmark::State& state) {
   TrackCounters track_counters;
   Fixture fixture;
-  grpc_completion_queue* cq = grpc_completion_queue_create_for_next(NULL);
+  grpc_completion_queue* cq = grpc_completion_queue_create_for_next(nullptr);
   gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
-  void* method_hdl =
-      grpc_channel_register_call(fixture.channel(), "/foo/bar", NULL, NULL);
+  void* method_hdl = grpc_channel_register_call(fixture.channel(), "/foo/bar",
+                                                nullptr, nullptr);
   while (state.KeepRunning()) {
     grpc_call_unref(grpc_channel_create_registered_call(
-        fixture.channel(), NULL, GRPC_PROPAGATE_DEFAULTS, cq, method_hdl,
-        deadline, NULL));
+        fixture.channel(), nullptr, GRPC_PROPAGATE_DEFAULTS, cq, method_hdl,
+        deadline, nullptr));
   }
   grpc_completion_queue_destroy(cq);
   track_counters.Finish(state);
@@ -161,7 +161,7 @@ static void BM_LameChannelCallCreateCore(benchmark::State& state) {
   grpc_completion_queue* cq;
   grpc_metadata_array initial_metadata_recv;
   grpc_metadata_array trailing_metadata_recv;
-  grpc_byte_buffer* response_payload_recv = NULL;
+  grpc_byte_buffer* response_payload_recv = nullptr;
   grpc_status_code status;
   grpc_slice details;
   grpc::testing::EchoRequest send_request;
@@ -170,14 +170,14 @@ static void BM_LameChannelCallCreateCore(benchmark::State& state) {
 
   channel = grpc_lame_client_channel_create(
       "localhost:1234", GRPC_STATUS_UNAUTHENTICATED, "blah");
-  cq = grpc_completion_queue_create_for_next(NULL);
+  cq = grpc_completion_queue_create_for_next(nullptr);
   void* rc = grpc_channel_register_call(
-      channel, "/grpc.testing.EchoTestService/Echo", NULL, NULL);
+      channel, "/grpc.testing.EchoTestService/Echo", nullptr, nullptr);
   while (state.KeepRunning()) {
     GPR_TIMER_SCOPE("BenchmarkCycle", 0);
     grpc_call* call = grpc_channel_create_registered_call(
-        channel, NULL, GRPC_PROPAGATE_DEFAULTS, cq, rc,
-        gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+        channel, nullptr, GRPC_PROPAGATE_DEFAULTS, cq, rc,
+        gpr_inf_future(GPR_CLOCK_REALTIME), nullptr);
     grpc_metadata_array_init(&initial_metadata_recv);
     grpc_metadata_array_init(&trailing_metadata_recv);
     grpc_byte_buffer* request_payload_send =
@@ -210,9 +210,9 @@ static void BM_LameChannelCallCreateCore(benchmark::State& state) {
 
     GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call, ops,
                                                      (size_t)(op - ops),
-                                                     (void*)1, NULL));
+                                                     (void*)1, nullptr));
     grpc_event ev = grpc_completion_queue_next(
-        cq, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+        cq, gpr_inf_future(GPR_CLOCK_REALTIME), nullptr);
     GPR_ASSERT(ev.type != GRPC_QUEUE_SHUTDOWN);
     GPR_ASSERT(ev.success != 0);
     grpc_call_unref(call);
@@ -235,7 +235,7 @@ static void BM_LameChannelCallCreateCoreSeparateBatch(benchmark::State& state) {
   grpc_completion_queue* cq;
   grpc_metadata_array initial_metadata_recv;
   grpc_metadata_array trailing_metadata_recv;
-  grpc_byte_buffer* response_payload_recv = NULL;
+  grpc_byte_buffer* response_payload_recv = nullptr;
   grpc_status_code status;
   grpc_slice details;
   grpc::testing::EchoRequest send_request;
@@ -244,14 +244,14 @@ static void BM_LameChannelCallCreateCoreSeparateBatch(benchmark::State& state) {
 
   channel = grpc_lame_client_channel_create(
       "localhost:1234", GRPC_STATUS_UNAUTHENTICATED, "blah");
-  cq = grpc_completion_queue_create_for_next(NULL);
+  cq = grpc_completion_queue_create_for_next(nullptr);
   void* rc = grpc_channel_register_call(
-      channel, "/grpc.testing.EchoTestService/Echo", NULL, NULL);
+      channel, "/grpc.testing.EchoTestService/Echo", nullptr, nullptr);
   while (state.KeepRunning()) {
     GPR_TIMER_SCOPE("BenchmarkCycle", 0);
     grpc_call* call = grpc_channel_create_registered_call(
-        channel, NULL, GRPC_PROPAGATE_DEFAULTS, cq, rc,
-        gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+        channel, nullptr, GRPC_PROPAGATE_DEFAULTS, cq, rc,
+        gpr_inf_future(GPR_CLOCK_REALTIME), nullptr);
     grpc_metadata_array_init(&initial_metadata_recv);
     grpc_metadata_array_init(&trailing_metadata_recv);
     grpc_byte_buffer* request_payload_send =
@@ -271,7 +271,7 @@ static void BM_LameChannelCallCreateCoreSeparateBatch(benchmark::State& state) {
     op++;
     GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call, ops,
                                                      (size_t)(op - ops),
-                                                     (void*)0, NULL));
+                                                     (void*)nullptr, nullptr));
     memset(ops, 0, sizeof(ops));
     op = ops;
     op->op = GRPC_OP_RECV_INITIAL_METADATA;
@@ -289,13 +289,13 @@ static void BM_LameChannelCallCreateCoreSeparateBatch(benchmark::State& state) {
 
     GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call, ops,
                                                      (size_t)(op - ops),
-                                                     (void*)1, NULL));
+                                                     (void*)1, nullptr));
     grpc_event ev = grpc_completion_queue_next(
-        cq, gpr_inf_future(GPR_CLOCK_REALTIME), NULL);
+        cq, gpr_inf_future(GPR_CLOCK_REALTIME), nullptr);
     GPR_ASSERT(ev.type != GRPC_QUEUE_SHUTDOWN);
     GPR_ASSERT(ev.success == 0);
     ev = grpc_completion_queue_next(cq, gpr_inf_future(GPR_CLOCK_REALTIME),
-                                    NULL);
+                                    nullptr);
     GPR_ASSERT(ev.type != GRPC_QUEUE_SHUTDOWN);
     GPR_ASSERT(ev.success != 0);
     grpc_call_unref(call);
@@ -538,7 +538,7 @@ static void BM_IsolatedFilter(benchmark::State& state) {
 
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   size_t channel_size = grpc_channel_stack_size(
-      filters.size() == 0 ? NULL : &filters[0], filters.size());
+      filters.size() == 0 ? nullptr : &filters[0], filters.size());
   grpc_channel_stack* channel_stack =
       static_cast<grpc_channel_stack*>(gpr_zalloc(channel_size));
   GPR_ASSERT(GRPC_LOG_IF_ERROR(
@@ -559,8 +559,8 @@ static void BM_IsolatedFilter(benchmark::State& state) {
   TestOp test_op_data;
   grpc_call_element_args call_args;
   call_args.call_stack = call_stack;
-  call_args.server_transport_data = NULL;
-  call_args.context = NULL;
+  call_args.server_transport_data = nullptr;
+  call_args.context = nullptr;
   call_args.path = method;
   call_args.start_time = start_time;
   call_args.deadline = deadline;
@@ -569,9 +569,9 @@ static void BM_IsolatedFilter(benchmark::State& state) {
   while (state.KeepRunning()) {
     GPR_TIMER_SCOPE("BenchmarkCycle", 0);
     GRPC_ERROR_UNREF(grpc_call_stack_init(&exec_ctx, channel_stack, 1,
-                                          DoNothing, NULL, &call_args));
+                                          DoNothing, nullptr, &call_args));
     typename TestOp::Op op(&exec_ctx, &test_op_data, call_stack);
-    grpc_call_stack_destroy(&exec_ctx, call_stack, &final_info, NULL);
+    grpc_call_stack_destroy(&exec_ctx, call_stack, &final_info, nullptr);
     op.Finish(&exec_ctx);
     grpc_exec_ctx_flush(&exec_ctx);
     // recreate arena every 64k iterations to avoid oom
@@ -708,14 +708,15 @@ class IsolatedCallFixture : public TrackCounters {
     grpc_channel_stack_builder_set_name(builder, "dummy");
     grpc_channel_stack_builder_set_target(builder, "dummy_target");
     GPR_ASSERT(grpc_channel_stack_builder_append_filter(
-        builder, &isolated_call_filter::isolated_call_filter, NULL, NULL));
+        builder, &isolated_call_filter::isolated_call_filter, nullptr,
+        nullptr));
     {
       grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
       channel_ = grpc_channel_create_with_builder(&exec_ctx, builder,
                                                   GRPC_CLIENT_CHANNEL);
       grpc_exec_ctx_finish(&exec_ctx);
     }
-    cq_ = grpc_completion_queue_create_for_next(NULL);
+    cq_ = grpc_completion_queue_create_for_next(nullptr);
   }
 
   void Finish(benchmark::State& state) {
@@ -735,13 +736,13 @@ class IsolatedCallFixture : public TrackCounters {
 static void BM_IsolatedCall_NoOp(benchmark::State& state) {
   IsolatedCallFixture fixture;
   gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
-  void* method_hdl =
-      grpc_channel_register_call(fixture.channel(), "/foo/bar", NULL, NULL);
+  void* method_hdl = grpc_channel_register_call(fixture.channel(), "/foo/bar",
+                                                nullptr, nullptr);
   while (state.KeepRunning()) {
     GPR_TIMER_SCOPE("BenchmarkCycle", 0);
     grpc_call_unref(grpc_channel_create_registered_call(
         fixture.channel(), nullptr, GRPC_PROPAGATE_DEFAULTS, fixture.cq(),
-        method_hdl, deadline, NULL));
+        method_hdl, deadline, nullptr));
   }
   fixture.Finish(state);
 }
@@ -750,11 +751,11 @@ BENCHMARK(BM_IsolatedCall_NoOp);
 static void BM_IsolatedCall_Unary(benchmark::State& state) {
   IsolatedCallFixture fixture;
   gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
-  void* method_hdl =
-      grpc_channel_register_call(fixture.channel(), "/foo/bar", NULL, NULL);
+  void* method_hdl = grpc_channel_register_call(fixture.channel(), "/foo/bar",
+                                                nullptr, nullptr);
   grpc_slice slice = grpc_slice_from_static_string("hello world");
   grpc_byte_buffer* send_message = grpc_raw_byte_buffer_create(&slice, 1);
-  grpc_byte_buffer* recv_message = NULL;
+  grpc_byte_buffer* recv_message = nullptr;
   grpc_status_code status_code;
   grpc_slice status_details = grpc_empty_slice();
   grpc_metadata_array recv_initial_metadata;
@@ -780,10 +781,10 @@ static void BM_IsolatedCall_Unary(benchmark::State& state) {
     GPR_TIMER_SCOPE("BenchmarkCycle", 0);
     grpc_call* call = grpc_channel_create_registered_call(
         fixture.channel(), nullptr, GRPC_PROPAGATE_DEFAULTS, fixture.cq(),
-        method_hdl, deadline, NULL);
-    grpc_call_start_batch(call, ops, 6, tag(1), NULL);
+        method_hdl, deadline, nullptr);
+    grpc_call_start_batch(call, ops, 6, tag(1), nullptr);
     grpc_completion_queue_next(fixture.cq(),
-                               gpr_inf_future(GPR_CLOCK_MONOTONIC), NULL);
+                               gpr_inf_future(GPR_CLOCK_MONOTONIC), nullptr);
     grpc_call_unref(call);
   }
   fixture.Finish(state);
@@ -796,8 +797,8 @@ BENCHMARK(BM_IsolatedCall_Unary);
 static void BM_IsolatedCall_StreamingSend(benchmark::State& state) {
   IsolatedCallFixture fixture;
   gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
-  void* method_hdl =
-      grpc_channel_register_call(fixture.channel(), "/foo/bar", NULL, NULL);
+  void* method_hdl = grpc_channel_register_call(fixture.channel(), "/foo/bar",
+                                                nullptr, nullptr);
   grpc_slice slice = grpc_slice_from_static_string("hello world");
   grpc_byte_buffer* send_message = grpc_raw_byte_buffer_create(&slice, 1);
   grpc_metadata_array recv_initial_metadata;
@@ -812,18 +813,18 @@ static void BM_IsolatedCall_StreamingSend(benchmark::State& state) {
       &recv_initial_metadata;
   grpc_call* call = grpc_channel_create_registered_call(
       fixture.channel(), nullptr, GRPC_PROPAGATE_DEFAULTS, fixture.cq(),
-      method_hdl, deadline, NULL);
-  grpc_call_start_batch(call, ops, 2, tag(1), NULL);
+      method_hdl, deadline, nullptr);
+  grpc_call_start_batch(call, ops, 2, tag(1), nullptr);
   grpc_completion_queue_next(fixture.cq(), gpr_inf_future(GPR_CLOCK_MONOTONIC),
-                             NULL);
+                             nullptr);
   memset(ops, 0, sizeof(ops));
   ops[0].op = GRPC_OP_SEND_MESSAGE;
   ops[0].data.send_message.send_message = send_message;
   while (state.KeepRunning()) {
     GPR_TIMER_SCOPE("BenchmarkCycle", 0);
-    grpc_call_start_batch(call, ops, 1, tag(2), NULL);
+    grpc_call_start_batch(call, ops, 1, tag(2), nullptr);
     grpc_completion_queue_next(fixture.cq(),
-                               gpr_inf_future(GPR_CLOCK_MONOTONIC), NULL);
+                               gpr_inf_future(GPR_CLOCK_MONOTONIC), nullptr);
   }
   grpc_call_unref(call);
   fixture.Finish(state);
diff --git a/test/cpp/microbenchmarks/bm_chttp2_hpack.cc b/test/cpp/microbenchmarks/bm_chttp2_hpack.cc
index 45f5382fde..3fff8b02d6 100644
--- a/test/cpp/microbenchmarks/bm_chttp2_hpack.cc
+++ b/test/cpp/microbenchmarks/bm_chttp2_hpack.cc
@@ -85,7 +85,7 @@ static void BM_HpackEncoderEncodeDeadline(benchmark::State& state) {
         (size_t)1024,
         &stats,
     };
-    grpc_chttp2_encode_header(&exec_ctx, &c, NULL, 0, &b, &hopt, &outbuf);
+    grpc_chttp2_encode_header(&exec_ctx, &c, nullptr, 0, &b, &hopt, &outbuf);
     grpc_slice_buffer_reset_and_unref_internal(&exec_ctx, &outbuf);
     grpc_exec_ctx_flush(&exec_ctx);
   }
@@ -136,7 +136,7 @@ static void BM_HpackEncoderEncodeHeader(benchmark::State& state) {
         (size_t)state.range(1),
         &stats,
     };
-    grpc_chttp2_encode_header(&exec_ctx, &c, NULL, 0, &b, &hopt, &outbuf);
+    grpc_chttp2_encode_header(&exec_ctx, &c, nullptr, 0, &b, &hopt, &outbuf);
     if (!logged_representative_output && state.iterations() > 3) {
       logged_representative_output = true;
       for (size_t i = 0; i < outbuf.count; i++) {
@@ -775,7 +775,7 @@ static void OnHeaderNew(grpc_exec_ctx* exec_ctx, void* user_data,
     grpc_millis* cached_timeout =
         static_cast<grpc_millis*>(grpc_mdelem_get_user_data(md, free_timeout));
     grpc_millis timeout;
-    if (cached_timeout != NULL) {
+    if (cached_timeout != nullptr) {
       timeout = *cached_timeout;
     } else {
       if (!grpc_http2_decode_timeout(GRPC_MDVALUE(md), &timeout)) {
diff --git a/test/cpp/microbenchmarks/bm_chttp2_transport.cc b/test/cpp/microbenchmarks/bm_chttp2_transport.cc
index 154cc91778..be4da4d0bd 100644
--- a/test/cpp/microbenchmarks/bm_chttp2_transport.cc
+++ b/test/cpp/microbenchmarks/bm_chttp2_transport.cc
@@ -100,7 +100,7 @@ class DummyEndpoint : public grpc_endpoint {
     GRPC_CLOSURE_SCHED(exec_ctx, cb, GRPC_ERROR_NONE);
   }
 
-  static grpc_workqueue* get_workqueue(grpc_endpoint* ep) { return NULL; }
+  static grpc_workqueue* get_workqueue(grpc_endpoint* ep) { return nullptr; }
 
   static void add_to_pollset(grpc_exec_ctx* exec_ctx, grpc_endpoint* ep,
                              grpc_pollset* pollset) {}
@@ -137,7 +137,7 @@ class Fixture {
     grpc_channel_args c_args = args.c_channel_args();
     ep_ = new DummyEndpoint;
     t_ = grpc_create_chttp2_transport(exec_ctx(), &c_args, ep_, client);
-    grpc_chttp2_transport_start_reading(exec_ctx(), t_, NULL);
+    grpc_chttp2_transport_start_reading(exec_ctx(), t_, nullptr, nullptr);
     FlushExecCtx();
   }
 
@@ -222,7 +222,7 @@ class Stream {
     }
     grpc_transport_init_stream(f_->exec_ctx(), f_->transport(),
                                static_cast<grpc_stream*>(stream_), &refcount_,
-                               NULL, arena_);
+                               nullptr, arena_);
   }
 
   void DestroyThen(grpc_exec_ctx* exec_ctx, grpc_closure* closure) {
@@ -586,7 +586,7 @@ static void BM_TransportStreamRecv(benchmark::State& state) {
       });
 
   drain_start = MakeClosure([&](grpc_exec_ctx* exec_ctx, grpc_error* error) {
-    if (recv_stream == NULL) {
+    if (recv_stream == nullptr) {
       GPR_ASSERT(!state.KeepRunning());
       return;
     }
diff --git a/test/cpp/microbenchmarks/bm_closure.cc b/test/cpp/microbenchmarks/bm_closure.cc
index 458a2ceb13..2434d4e84e 100644
--- a/test/cpp/microbenchmarks/bm_closure.cc
+++ b/test/cpp/microbenchmarks/bm_closure.cc
@@ -59,7 +59,7 @@ static void BM_ClosureInitAgainstExecCtx(benchmark::State& state) {
   grpc_closure c;
   while (state.KeepRunning()) {
     benchmark::DoNotOptimize(
-        GRPC_CLOSURE_INIT(&c, DoNothing, NULL, grpc_schedule_on_exec_ctx));
+        GRPC_CLOSURE_INIT(&c, DoNothing, nullptr, grpc_schedule_on_exec_ctx));
   }
   track_counters.Finish(state);
 }
@@ -72,7 +72,7 @@ static void BM_ClosureInitAgainstCombiner(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     benchmark::DoNotOptimize(GRPC_CLOSURE_INIT(
-        &c, DoNothing, NULL, grpc_combiner_scheduler(combiner)));
+        &c, DoNothing, nullptr, grpc_combiner_scheduler(combiner)));
   }
   GRPC_COMBINER_UNREF(&exec_ctx, combiner, "finished");
   grpc_exec_ctx_finish(&exec_ctx);
@@ -83,7 +83,7 @@ BENCHMARK(BM_ClosureInitAgainstCombiner);
 static void BM_ClosureRunOnExecCtx(benchmark::State& state) {
   TrackCounters track_counters;
   grpc_closure c;
-  GRPC_CLOSURE_INIT(&c, DoNothing, NULL, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&c, DoNothing, nullptr, grpc_schedule_on_exec_ctx);
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_RUN(&exec_ctx, &c, GRPC_ERROR_NONE);
@@ -100,7 +100,7 @@ static void BM_ClosureCreateAndRun(benchmark::State& state) {
   while (state.KeepRunning()) {
     GRPC_CLOSURE_RUN(
         &exec_ctx,
-        GRPC_CLOSURE_CREATE(DoNothing, NULL, grpc_schedule_on_exec_ctx),
+        GRPC_CLOSURE_CREATE(DoNothing, nullptr, grpc_schedule_on_exec_ctx),
         GRPC_ERROR_NONE);
   }
   grpc_exec_ctx_finish(&exec_ctx);
@@ -115,7 +115,7 @@ static void BM_ClosureInitAndRun(benchmark::State& state) {
   while (state.KeepRunning()) {
     GRPC_CLOSURE_RUN(
         &exec_ctx,
-        GRPC_CLOSURE_INIT(&c, DoNothing, NULL, grpc_schedule_on_exec_ctx),
+        GRPC_CLOSURE_INIT(&c, DoNothing, nullptr, grpc_schedule_on_exec_ctx),
         GRPC_ERROR_NONE);
   }
   grpc_exec_ctx_finish(&exec_ctx);
@@ -126,7 +126,7 @@ BENCHMARK(BM_ClosureInitAndRun);
 static void BM_ClosureSchedOnExecCtx(benchmark::State& state) {
   TrackCounters track_counters;
   grpc_closure c;
-  GRPC_CLOSURE_INIT(&c, DoNothing, NULL, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&c, DoNothing, nullptr, grpc_schedule_on_exec_ctx);
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c, GRPC_ERROR_NONE);
@@ -141,8 +141,8 @@ static void BM_ClosureSched2OnExecCtx(benchmark::State& state) {
   TrackCounters track_counters;
   grpc_closure c1;
   grpc_closure c2;
-  GRPC_CLOSURE_INIT(&c1, DoNothing, NULL, grpc_schedule_on_exec_ctx);
-  GRPC_CLOSURE_INIT(&c2, DoNothing, NULL, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&c1, DoNothing, nullptr, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&c2, DoNothing, nullptr, grpc_schedule_on_exec_ctx);
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c1, GRPC_ERROR_NONE);
@@ -159,9 +159,9 @@ static void BM_ClosureSched3OnExecCtx(benchmark::State& state) {
   grpc_closure c1;
   grpc_closure c2;
   grpc_closure c3;
-  GRPC_CLOSURE_INIT(&c1, DoNothing, NULL, grpc_schedule_on_exec_ctx);
-  GRPC_CLOSURE_INIT(&c2, DoNothing, NULL, grpc_schedule_on_exec_ctx);
-  GRPC_CLOSURE_INIT(&c3, DoNothing, NULL, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&c1, DoNothing, nullptr, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&c2, DoNothing, nullptr, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&c3, DoNothing, nullptr, grpc_schedule_on_exec_ctx);
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c1, GRPC_ERROR_NONE);
@@ -182,7 +182,7 @@ static void BM_AcquireMutex(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     gpr_mu_lock(&mu);
-    DoNothing(&exec_ctx, NULL, GRPC_ERROR_NONE);
+    DoNothing(&exec_ctx, nullptr, GRPC_ERROR_NONE);
     gpr_mu_unlock(&mu);
   }
   grpc_exec_ctx_finish(&exec_ctx);
@@ -198,7 +198,7 @@ static void BM_TryAcquireMutex(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     if (gpr_mu_trylock(&mu)) {
-      DoNothing(&exec_ctx, NULL, GRPC_ERROR_NONE);
+      DoNothing(&exec_ctx, nullptr, GRPC_ERROR_NONE);
       gpr_mu_unlock(&mu);
     } else {
       abort();
@@ -216,7 +216,7 @@ static void BM_AcquireSpinlock(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     gpr_spinlock_lock(&mu);
-    DoNothing(&exec_ctx, NULL, GRPC_ERROR_NONE);
+    DoNothing(&exec_ctx, nullptr, GRPC_ERROR_NONE);
     gpr_spinlock_unlock(&mu);
   }
   grpc_exec_ctx_finish(&exec_ctx);
@@ -231,7 +231,7 @@ static void BM_TryAcquireSpinlock(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     if (gpr_spinlock_trylock(&mu)) {
-      DoNothing(&exec_ctx, NULL, GRPC_ERROR_NONE);
+      DoNothing(&exec_ctx, nullptr, GRPC_ERROR_NONE);
       gpr_spinlock_unlock(&mu);
     } else {
       abort();
@@ -246,7 +246,7 @@ static void BM_ClosureSchedOnCombiner(benchmark::State& state) {
   TrackCounters track_counters;
   grpc_combiner* combiner = grpc_combiner_create();
   grpc_closure c;
-  GRPC_CLOSURE_INIT(&c, DoNothing, NULL, grpc_combiner_scheduler(combiner));
+  GRPC_CLOSURE_INIT(&c, DoNothing, nullptr, grpc_combiner_scheduler(combiner));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c, GRPC_ERROR_NONE);
@@ -263,8 +263,8 @@ static void BM_ClosureSched2OnCombiner(benchmark::State& state) {
   grpc_combiner* combiner = grpc_combiner_create();
   grpc_closure c1;
   grpc_closure c2;
-  GRPC_CLOSURE_INIT(&c1, DoNothing, NULL, grpc_combiner_scheduler(combiner));
-  GRPC_CLOSURE_INIT(&c2, DoNothing, NULL, grpc_combiner_scheduler(combiner));
+  GRPC_CLOSURE_INIT(&c1, DoNothing, nullptr, grpc_combiner_scheduler(combiner));
+  GRPC_CLOSURE_INIT(&c2, DoNothing, nullptr, grpc_combiner_scheduler(combiner));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c1, GRPC_ERROR_NONE);
@@ -283,9 +283,9 @@ static void BM_ClosureSched3OnCombiner(benchmark::State& state) {
   grpc_closure c1;
   grpc_closure c2;
   grpc_closure c3;
-  GRPC_CLOSURE_INIT(&c1, DoNothing, NULL, grpc_combiner_scheduler(combiner));
-  GRPC_CLOSURE_INIT(&c2, DoNothing, NULL, grpc_combiner_scheduler(combiner));
-  GRPC_CLOSURE_INIT(&c3, DoNothing, NULL, grpc_combiner_scheduler(combiner));
+  GRPC_CLOSURE_INIT(&c1, DoNothing, nullptr, grpc_combiner_scheduler(combiner));
+  GRPC_CLOSURE_INIT(&c2, DoNothing, nullptr, grpc_combiner_scheduler(combiner));
+  GRPC_CLOSURE_INIT(&c3, DoNothing, nullptr, grpc_combiner_scheduler(combiner));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c1, GRPC_ERROR_NONE);
@@ -305,8 +305,10 @@ static void BM_ClosureSched2OnTwoCombiners(benchmark::State& state) {
   grpc_combiner* combiner2 = grpc_combiner_create();
   grpc_closure c1;
   grpc_closure c2;
-  GRPC_CLOSURE_INIT(&c1, DoNothing, NULL, grpc_combiner_scheduler(combiner1));
-  GRPC_CLOSURE_INIT(&c2, DoNothing, NULL, grpc_combiner_scheduler(combiner2));
+  GRPC_CLOSURE_INIT(&c1, DoNothing, nullptr,
+                    grpc_combiner_scheduler(combiner1));
+  GRPC_CLOSURE_INIT(&c2, DoNothing, nullptr,
+                    grpc_combiner_scheduler(combiner2));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c1, GRPC_ERROR_NONE);
@@ -328,10 +330,14 @@ static void BM_ClosureSched4OnTwoCombiners(benchmark::State& state) {
   grpc_closure c2;
   grpc_closure c3;
   grpc_closure c4;
-  GRPC_CLOSURE_INIT(&c1, DoNothing, NULL, grpc_combiner_scheduler(combiner1));
-  GRPC_CLOSURE_INIT(&c2, DoNothing, NULL, grpc_combiner_scheduler(combiner2));
-  GRPC_CLOSURE_INIT(&c3, DoNothing, NULL, grpc_combiner_scheduler(combiner1));
-  GRPC_CLOSURE_INIT(&c4, DoNothing, NULL, grpc_combiner_scheduler(combiner2));
+  GRPC_CLOSURE_INIT(&c1, DoNothing, nullptr,
+                    grpc_combiner_scheduler(combiner1));
+  GRPC_CLOSURE_INIT(&c2, DoNothing, nullptr,
+                    grpc_combiner_scheduler(combiner2));
+  GRPC_CLOSURE_INIT(&c3, DoNothing, nullptr,
+                    grpc_combiner_scheduler(combiner1));
+  GRPC_CLOSURE_INIT(&c4, DoNothing, nullptr,
+                    grpc_combiner_scheduler(combiner2));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     GRPC_CLOSURE_SCHED(&exec_ctx, &c1, GRPC_ERROR_NONE);
diff --git a/test/cpp/microbenchmarks/bm_cq.cc b/test/cpp/microbenchmarks/bm_cq.cc
index dac702b08b..f0dede7333 100644
--- a/test/cpp/microbenchmarks/bm_cq.cc
+++ b/test/cpp/microbenchmarks/bm_cq.cc
@@ -47,7 +47,7 @@ static void BM_CreateDestroyCpp2(benchmark::State& state) {
   TrackCounters track_counters;
   while (state.KeepRunning()) {
     grpc_completion_queue* core_cq =
-        grpc_completion_queue_create_for_next(NULL);
+        grpc_completion_queue_create_for_next(nullptr);
     CompletionQueue cq(core_cq);
   }
   track_counters.Finish(state);
@@ -59,7 +59,8 @@ static void BM_CreateDestroyCore(benchmark::State& state) {
   while (state.KeepRunning()) {
     // TODO: sreek Templatize this benchmark and pass completion type and
     // polling type as parameters
-    grpc_completion_queue_destroy(grpc_completion_queue_create_for_next(NULL));
+    grpc_completion_queue_destroy(
+        grpc_completion_queue_create_for_next(nullptr));
   }
   track_counters.Finish(state);
 }
@@ -83,7 +84,7 @@ static void BM_Pass1Cpp(benchmark::State& state) {
     grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
     GPR_ASSERT(grpc_cq_begin_op(c_cq, &dummy_tag));
     grpc_cq_end_op(&exec_ctx, c_cq, &dummy_tag, GRPC_ERROR_NONE,
-                   DoneWithCompletionOnStack, NULL, &completion);
+                   DoneWithCompletionOnStack, nullptr, &completion);
     grpc_exec_ctx_finish(&exec_ctx);
     void* tag;
     bool ok;
@@ -96,16 +97,16 @@ BENCHMARK(BM_Pass1Cpp);
 static void BM_Pass1Core(benchmark::State& state) {
   TrackCounters track_counters;
   // TODO: sreek Templatize this benchmark and pass polling_type as a param
-  grpc_completion_queue* cq = grpc_completion_queue_create_for_next(NULL);
+  grpc_completion_queue* cq = grpc_completion_queue_create_for_next(nullptr);
   gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
   while (state.KeepRunning()) {
     grpc_cq_completion completion;
     grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-    GPR_ASSERT(grpc_cq_begin_op(cq, NULL));
-    grpc_cq_end_op(&exec_ctx, cq, NULL, GRPC_ERROR_NONE,
-                   DoneWithCompletionOnStack, NULL, &completion);
+    GPR_ASSERT(grpc_cq_begin_op(cq, nullptr));
+    grpc_cq_end_op(&exec_ctx, cq, nullptr, GRPC_ERROR_NONE,
+                   DoneWithCompletionOnStack, nullptr, &completion);
     grpc_exec_ctx_finish(&exec_ctx);
-    grpc_completion_queue_next(cq, deadline, NULL);
+    grpc_completion_queue_next(cq, deadline, nullptr);
   }
   grpc_completion_queue_destroy(cq);
   track_counters.Finish(state);
@@ -115,16 +116,16 @@ BENCHMARK(BM_Pass1Core);
 static void BM_Pluck1Core(benchmark::State& state) {
   TrackCounters track_counters;
   // TODO: sreek Templatize this benchmark and pass polling_type as a param
-  grpc_completion_queue* cq = grpc_completion_queue_create_for_pluck(NULL);
+  grpc_completion_queue* cq = grpc_completion_queue_create_for_pluck(nullptr);
   gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);
   while (state.KeepRunning()) {
     grpc_cq_completion completion;
     grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-    GPR_ASSERT(grpc_cq_begin_op(cq, NULL));
-    grpc_cq_end_op(&exec_ctx, cq, NULL, GRPC_ERROR_NONE,
-                   DoneWithCompletionOnStack, NULL, &completion);
+    GPR_ASSERT(grpc_cq_begin_op(cq, nullptr));
+    grpc_cq_end_op(&exec_ctx, cq, nullptr, GRPC_ERROR_NONE,
+                   DoneWithCompletionOnStack, nullptr, &completion);
     grpc_exec_ctx_finish(&exec_ctx);
-    grpc_completion_queue_pluck(cq, NULL, deadline, NULL);
+    grpc_completion_queue_pluck(cq, nullptr, deadline, nullptr);
   }
   grpc_completion_queue_destroy(cq);
   track_counters.Finish(state);
@@ -134,10 +135,10 @@ BENCHMARK(BM_Pluck1Core);
 static void BM_EmptyCore(benchmark::State& state) {
   TrackCounters track_counters;
   // TODO: sreek Templatize this benchmark and pass polling_type as a param
-  grpc_completion_queue* cq = grpc_completion_queue_create_for_next(NULL);
+  grpc_completion_queue* cq = grpc_completion_queue_create_for_next(nullptr);
   gpr_timespec deadline = gpr_inf_past(GPR_CLOCK_MONOTONIC);
   while (state.KeepRunning()) {
-    grpc_completion_queue_next(cq, deadline, NULL);
+    grpc_completion_queue_next(cq, deadline, nullptr);
   }
   grpc_completion_queue_destroy(cq);
   track_counters.Finish(state);
diff --git a/test/cpp/microbenchmarks/bm_cq_multiple_threads.cc b/test/cpp/microbenchmarks/bm_cq_multiple_threads.cc
index 8d4349a297..7ccebb55ee 100644
--- a/test/cpp/microbenchmarks/bm_cq_multiple_threads.cc
+++ b/test/cpp/microbenchmarks/bm_cq_multiple_threads.cc
@@ -80,7 +80,7 @@ static grpc_error* pollset_work(grpc_exec_ctx* exec_ctx, grpc_pollset* ps,
 
   gpr_mu_unlock(&ps->mu);
   GPR_ASSERT(grpc_cq_begin_op(g_cq, g_tag));
-  grpc_cq_end_op(exec_ctx, g_cq, g_tag, GRPC_ERROR_NONE, cq_done_cb, NULL,
+  grpc_cq_end_op(exec_ctx, g_cq, g_tag, GRPC_ERROR_NONE, cq_done_cb, nullptr,
                  (grpc_cq_completion*)gpr_malloc(sizeof(grpc_cq_completion)));
   grpc_exec_ctx_flush(exec_ctx);
   gpr_mu_lock(&ps->mu);
@@ -108,7 +108,7 @@ static void setup() {
   g_old_vtable = grpc_get_event_engine_test_only();
   grpc_set_event_engine_test_only(&g_vtable);
 
-  g_cq = grpc_completion_queue_create_for_next(NULL);
+  g_cq = grpc_completion_queue_create_for_next(nullptr);
 }
 
 static void teardown() {
@@ -116,7 +116,7 @@ static void teardown() {
 
   /* Drain any events */
   gpr_timespec deadline = gpr_time_0(GPR_CLOCK_MONOTONIC);
-  while (grpc_completion_queue_next(g_cq, deadline, NULL).type !=
+  while (grpc_completion_queue_next(g_cq, deadline, nullptr).type !=
          GRPC_QUEUE_SHUTDOWN) {
     /* Do nothing */
   }
@@ -151,7 +151,7 @@ static void BM_Cq_Throughput(benchmark::State& state) {
   }
 
   while (state.KeepRunning()) {
-    GPR_ASSERT(grpc_completion_queue_next(g_cq, deadline, NULL).type ==
+    GPR_ASSERT(grpc_completion_queue_next(g_cq, deadline, nullptr).type ==
                GRPC_OP_COMPLETE);
   }
 
diff --git a/test/cpp/microbenchmarks/bm_error.cc b/test/cpp/microbenchmarks/bm_error.cc
index aa7822653f..bbd8b3c339 100644
--- a/test/cpp/microbenchmarks/bm_error.cc
+++ b/test/cpp/microbenchmarks/bm_error.cc
@@ -251,7 +251,7 @@ static void BM_ErrorGetStatus(benchmark::State& state) {
     grpc_status_code status;
     grpc_slice slice;
     grpc_error_get_status(&exec_ctx, fixture.error(), fixture.deadline(),
-                          &status, &slice, NULL);
+                          &status, &slice, nullptr, nullptr);
   }
   grpc_exec_ctx_finish(&exec_ctx);
   track_counters.Finish(state);
@@ -265,7 +265,7 @@ static void BM_ErrorGetStatusCode(benchmark::State& state) {
   while (state.KeepRunning()) {
     grpc_status_code status;
     grpc_error_get_status(&exec_ctx, fixture.error(), fixture.deadline(),
-                          &status, NULL, NULL);
+                          &status, nullptr, nullptr, nullptr);
   }
   grpc_exec_ctx_finish(&exec_ctx);
   track_counters.Finish(state);
@@ -278,8 +278,8 @@ static void BM_ErrorHttpError(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
     grpc_http2_error_code error;
-    grpc_error_get_status(&exec_ctx, fixture.error(), fixture.deadline(), NULL,
-                          NULL, &error);
+    grpc_error_get_status(&exec_ctx, fixture.error(), fixture.deadline(),
+                          nullptr, nullptr, &error, nullptr);
   }
   grpc_exec_ctx_finish(&exec_ctx);
   track_counters.Finish(state);
diff --git a/test/cpp/microbenchmarks/bm_fullstack_trickle.cc b/test/cpp/microbenchmarks/bm_fullstack_trickle.cc
index f75c3e4436..5e72213823 100644
--- a/test/cpp/microbenchmarks/bm_fullstack_trickle.cc
+++ b/test/cpp/microbenchmarks/bm_fullstack_trickle.cc
@@ -216,10 +216,10 @@ class TrickledCHTTP2 : public EndpointPairFixture {
   void UpdateStats(grpc_chttp2_transport* t, Stats* s,
                    size_t backlog) GPR_ATTRIBUTE_NO_TSAN {
     if (backlog == 0) {
-      if (t->lists[GRPC_CHTTP2_LIST_STALLED_BY_STREAM].head != NULL) {
+      if (t->lists[GRPC_CHTTP2_LIST_STALLED_BY_STREAM].head != nullptr) {
         s->streams_stalled_due_to_stream_flow_control++;
       }
-      if (t->lists[GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT].head != NULL) {
+      if (t->lists[GRPC_CHTTP2_LIST_STALLED_BY_TRANSPORT].head != nullptr) {
         s->streams_stalled_due_to_transport_flow_control++;
       }
     }
@@ -445,7 +445,7 @@ BENCHMARK(BM_PumpUnbalancedUnary_Trickle)->Apply(UnaryTrickleArgs);
 }  // namespace testing
 }  // namespace grpc
 
-extern "C" gpr_timespec (*gpr_now_impl)(gpr_clock_type clock_type);
+extern gpr_timespec (*gpr_now_impl)(gpr_clock_type clock_type);
 
 int main(int argc, char** argv) {
   ::benchmark::Initialize(&argc, argv);
diff --git a/test/cpp/microbenchmarks/bm_metadata.cc b/test/cpp/microbenchmarks/bm_metadata.cc
index 1ed05f7466..73bce08466 100644
--- a/test/cpp/microbenchmarks/bm_metadata.cc
+++ b/test/cpp/microbenchmarks/bm_metadata.cc
@@ -92,7 +92,7 @@ static void BM_MetadataFromNonInternedSlices(benchmark::State& state) {
   gpr_slice v = grpc_slice_from_static_string("value");
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
-    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, NULL));
+    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, nullptr));
   }
   grpc_exec_ctx_finish(&exec_ctx);
   track_counters.Finish(state);
@@ -105,7 +105,7 @@ static void BM_MetadataFromInternedSlices(benchmark::State& state) {
   gpr_slice v = grpc_slice_intern(grpc_slice_from_static_string("value"));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
-    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, NULL));
+    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, nullptr));
   }
   grpc_exec_ctx_finish(&exec_ctx);
   grpc_slice_unref(k);
@@ -120,9 +120,9 @@ static void BM_MetadataFromInternedSlicesAlreadyInIndex(
   gpr_slice k = grpc_slice_intern(grpc_slice_from_static_string("key"));
   gpr_slice v = grpc_slice_intern(grpc_slice_from_static_string("value"));
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
-  grpc_mdelem seed = grpc_mdelem_create(&exec_ctx, k, v, NULL);
+  grpc_mdelem seed = grpc_mdelem_create(&exec_ctx, k, v, nullptr);
   while (state.KeepRunning()) {
-    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, NULL));
+    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, nullptr));
   }
   GRPC_MDELEM_UNREF(&exec_ctx, seed);
   grpc_exec_ctx_finish(&exec_ctx);
@@ -138,7 +138,7 @@ static void BM_MetadataFromInternedKey(benchmark::State& state) {
   gpr_slice v = grpc_slice_from_static_string("value");
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
-    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, NULL));
+    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, nullptr));
   }
   grpc_exec_ctx_finish(&exec_ctx);
   grpc_slice_unref(k);
@@ -209,7 +209,7 @@ static void BM_MetadataFromStaticMetadataStrings(benchmark::State& state) {
   gpr_slice v = GRPC_MDSTR_200;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
-    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, NULL));
+    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, nullptr));
   }
   grpc_exec_ctx_finish(&exec_ctx);
   grpc_slice_unref(k);
@@ -224,7 +224,7 @@ static void BM_MetadataFromStaticMetadataStringsNotIndexed(
   gpr_slice v = GRPC_MDSTR_GZIP;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   while (state.KeepRunning()) {
-    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, NULL));
+    GRPC_MDELEM_UNREF(&exec_ctx, grpc_mdelem_create(&exec_ctx, k, v, nullptr));
   }
   grpc_exec_ctx_finish(&exec_ctx);
   grpc_slice_unref(k);
@@ -273,7 +273,7 @@ static void BM_MetadataRefUnrefAllocated(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_mdelem el =
       grpc_mdelem_create(&exec_ctx, grpc_slice_from_static_string("a"),
-                         grpc_slice_from_static_string("b"), NULL);
+                         grpc_slice_from_static_string("b"), nullptr);
   while (state.KeepRunning()) {
     GRPC_MDELEM_UNREF(&exec_ctx, GRPC_MDELEM_REF(el));
   }
@@ -287,7 +287,7 @@ static void BM_MetadataRefUnrefStatic(benchmark::State& state) {
   TrackCounters track_counters;
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   grpc_mdelem el =
-      grpc_mdelem_create(&exec_ctx, GRPC_MDSTR_STATUS, GRPC_MDSTR_200, NULL);
+      grpc_mdelem_create(&exec_ctx, GRPC_MDSTR_STATUS, GRPC_MDSTR_200, nullptr);
   while (state.KeepRunning()) {
     GRPC_MDELEM_UNREF(&exec_ctx, GRPC_MDELEM_REF(el));
   }
diff --git a/test/cpp/microbenchmarks/bm_pollset.cc b/test/cpp/microbenchmarks/bm_pollset.cc
index 92d76f307e..4da79693f1 100644
--- a/test/cpp/microbenchmarks/bm_pollset.cc
+++ b/test/cpp/microbenchmarks/bm_pollset.cc
@@ -117,7 +117,7 @@ static void BM_PollEmptyPollset(benchmark::State& state) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   gpr_mu_lock(mu);
   while (state.KeepRunning()) {
-    GRPC_ERROR_UNREF(grpc_pollset_work(&exec_ctx, ps, NULL, 0));
+    GRPC_ERROR_UNREF(grpc_pollset_work(&exec_ctx, ps, nullptr, 0));
   }
   grpc_closure shutdown_ps_closure;
   GRPC_CLOSURE_INIT(&shutdown_ps_closure, shutdown_ps, ps,
@@ -145,7 +145,8 @@ static void BM_PollAddFd(benchmark::State& state) {
     grpc_pollset_add_fd(&exec_ctx, ps, fd);
     grpc_exec_ctx_flush(&exec_ctx);
   }
-  grpc_fd_orphan(&exec_ctx, fd, NULL, NULL, false /* already_closed */, "xxx");
+  grpc_fd_orphan(&exec_ctx, fd, nullptr, nullptr, false /* already_closed */,
+                 "xxx");
   grpc_closure shutdown_ps_closure;
   GRPC_CLOSURE_INIT(&shutdown_ps_closure, shutdown_ps, ps,
                     grpc_schedule_on_exec_ctx);
@@ -240,10 +241,10 @@ static void BM_SingleThreadPollOneFd(benchmark::State& state) {
   gpr_mu_lock(mu);
   while (!done) {
     GRPC_ERROR_UNREF(
-        grpc_pollset_work(&exec_ctx, ps, NULL, GRPC_MILLIS_INF_FUTURE));
+        grpc_pollset_work(&exec_ctx, ps, nullptr, GRPC_MILLIS_INF_FUTURE));
   }
-  grpc_fd_orphan(&exec_ctx, wakeup, NULL, NULL, false /* already_closed */,
-                 "done");
+  grpc_fd_orphan(&exec_ctx, wakeup, nullptr, nullptr,
+                 false /* already_closed */, "done");
   wakeup_fd.read_fd = 0;
   grpc_closure shutdown_ps_closure;
   GRPC_CLOSURE_INIT(&shutdown_ps_closure, shutdown_ps, ps,
diff --git a/test/cpp/microbenchmarks/fullstack_fixtures.h b/test/cpp/microbenchmarks/fullstack_fixtures.h
index 71bbb393db..7e20843875 100644
--- a/test/cpp/microbenchmarks/fullstack_fixtures.h
+++ b/test/cpp/microbenchmarks/fullstack_fixtures.h
@@ -174,7 +174,7 @@ class EndpointPairFixture : public BaseFixture {
       const grpc_channel_args* server_args =
           grpc_server_get_channel_args(server_->c_server());
       server_transport_ = grpc_create_chttp2_transport(
-          &exec_ctx, server_args, endpoints.server, 0 /* is_client */);
+          &exec_ctx, server_args, endpoints.server, false /* is_client */);
 
       grpc_pollset** pollsets;
       size_t num_pollsets = 0;
@@ -185,8 +185,9 @@ class EndpointPairFixture : public BaseFixture {
       }
 
       grpc_server_setup_transport(&exec_ctx, server_->c_server(),
-                                  server_transport_, NULL, server_args);
-      grpc_chttp2_transport_start_reading(&exec_ctx, server_transport_, NULL);
+                                  server_transport_, nullptr, server_args);
+      grpc_chttp2_transport_start_reading(&exec_ctx, server_transport_, nullptr,
+                                          nullptr);
     }
 
     /* create channel */
@@ -196,13 +197,14 @@ class EndpointPairFixture : public BaseFixture {
       fixture_configuration.ApplyCommonChannelArguments(&args);
 
       grpc_channel_args c_args = args.c_channel_args();
-      client_transport_ =
-          grpc_create_chttp2_transport(&exec_ctx, &c_args, endpoints.client, 1);
+      client_transport_ = grpc_create_chttp2_transport(&exec_ctx, &c_args,
+                                                       endpoints.client, true);
       GPR_ASSERT(client_transport_);
       grpc_channel* channel =
           grpc_channel_create(&exec_ctx, "target", &c_args,
                               GRPC_CLIENT_DIRECT_CHANNEL, client_transport_);
-      grpc_chttp2_transport_start_reading(&exec_ctx, client_transport_, NULL);
+      grpc_chttp2_transport_start_reading(&exec_ctx, client_transport_, nullptr,
+                                          nullptr);
 
       channel_ = CreateChannelInternal("", channel);
     }
@@ -244,7 +246,7 @@ class SockPair : public EndpointPairFixture {
   SockPair(Service* service, const FixtureConfiguration& fixture_configuration =
                                  FixtureConfiguration())
       : EndpointPairFixture(service,
-                            grpc_iomgr_create_endpoint_pair("test", NULL),
+                            grpc_iomgr_create_endpoint_pair("test", nullptr),
                             fixture_configuration) {}
 };
 
diff --git a/test/cpp/microbenchmarks/helpers.h b/test/cpp/microbenchmarks/helpers.h
index 07be589df6..afa3e0f3ca 100644
--- a/test/cpp/microbenchmarks/helpers.h
+++ b/test/cpp/microbenchmarks/helpers.h
@@ -54,10 +54,10 @@ class Library {
 };
 
 #ifdef GPR_LOW_LEVEL_COUNTERS
-extern "C" gpr_atm gpr_mu_locks;
-extern "C" gpr_atm gpr_counter_atm_cas;
-extern "C" gpr_atm gpr_counter_atm_add;
-extern "C" gpr_atm gpr_now_call_count;
+extern gpr_atm gpr_mu_locks;
+extern gpr_atm gpr_counter_atm_cas;
+extern gpr_atm gpr_counter_atm_add;
+extern gpr_atm gpr_now_call_count;
 #endif
 
 class TrackCounters {
diff --git a/test/cpp/naming/README.md b/test/cpp/naming/README.md
index e33184620c..e0dd208465 100644
--- a/test/cpp/naming/README.md
+++ b/test/cpp/naming/README.md
@@ -31,7 +31,7 @@ After making a change to `resolver_test_record_groups.yaml`:
 3. From the repo root, run:
 
 ```
-$ test/cpp/naming/create_dns_private_zone.sh
+$ test/cpp/naming/create_private_dns_zone.sh
 $ test/cpp/naming/private_dns_zone_init.sh
 ```
 
diff --git a/test/cpp/naming/create_private_dns_zone.sh b/test/cpp/naming/create_private_dns_zone.sh
index 3d7520b90a..55a4cfe36e 100755
--- a/test/cpp/naming/create_private_dns_zone.sh
+++ b/test/cpp/naming/create_private_dns_zone.sh
@@ -20,8 +20,8 @@ set -ex
 cd $(dirname $0)/../../..
 
 gcloud alpha dns managed-zones create \
-  resolver-tests-version-1-grpctestingexp-zone-id \
-  --dns-name=resolver-tests-version-1.grpctestingexp. \
+  resolver-tests-version-4-grpctestingexp-zone-id \
+  --dns-name=resolver-tests-version-4.grpctestingexp. \
   --description="GCE-DNS-private-zone-for-GRPC-testing" \
   --visibility=private \
   --networks=default
diff --git a/test/cpp/naming/private_dns_zone_init.sh b/test/cpp/naming/private_dns_zone_init.sh
index 4eaf750ab7..8fa5a8a475 100755
--- a/test/cpp/naming/private_dns_zone_init.sh
+++ b/test/cpp/naming/private_dns_zone_init.sh
@@ -19,197 +19,197 @@ set -ex
 
 cd $(dirname $0)/../../..
 
-gcloud dns record-sets transaction start -z=resolver-tests-version-1-grpctestingexp-zone-id
+gcloud dns record-sets transaction start -z=resolver-tests-version-4-grpctestingexp-zone-id
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=_grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-4.grpctestingexp. \
   --type=SRV \
   --ttl=2100 \
-  "0 0 1234 ipv4-single-target.resolver-tests-version-1.grpctestingexp."
+  "0 0 1234 ipv4-single-target.resolver-tests-version-4.grpctestingexp."
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-single-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-single-target.resolver-tests-version-4.grpctestingexp. \
   --type=A \
   --ttl=2100 \
   "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=_grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-4.grpctestingexp. \
   --type=SRV \
   --ttl=2100 \
-  "0 0 1234 ipv4-multi-target.resolver-tests-version-1.grpctestingexp."
+  "0 0 1234 ipv4-multi-target.resolver-tests-version-4.grpctestingexp."
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-multi-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-multi-target.resolver-tests-version-4.grpctestingexp. \
   --type=A \
   --ttl=2100 \
   "1.2.3.5" "1.2.3.6" "1.2.3.7"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=_grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-4.grpctestingexp. \
   --type=SRV \
   --ttl=2100 \
-  "0 0 1234 ipv6-single-target.resolver-tests-version-1.grpctestingexp."
+  "0 0 1234 ipv6-single-target.resolver-tests-version-4.grpctestingexp."
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv6-single-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv6-single-target.resolver-tests-version-4.grpctestingexp. \
   --type=AAAA \
   --ttl=2100 \
   "2607:f8b0:400a:801::1001"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=_grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-4.grpctestingexp. \
   --type=SRV \
   --ttl=2100 \
-  "0 0 1234 ipv6-multi-target.resolver-tests-version-1.grpctestingexp."
+  "0 0 1234 ipv6-multi-target.resolver-tests-version-4.grpctestingexp."
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv6-multi-target.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv6-multi-target.resolver-tests-version-4.grpctestingexp. \
   --type=AAAA \
   --ttl=2100 \
   "2607:f8b0:400a:801::1002" "2607:f8b0:400a:801::1003" "2607:f8b0:400a:801::1004"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpc_config.srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. \
   --type=TXT \
   --ttl=2100 \
   '"grpc_config=[{\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"SimpleService\",\"waitForReady\":true}]}]}}]"'
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. \
-  --type=A \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. \
+  --type=SRV \
   --ttl=2100 \
-  "1.2.3.4"
+  "0 0 1234 ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp."
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=_grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. \
-  --type=SRV \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. \
+  --type=A \
   --ttl=2100 \
-  "0 0 1234 ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp."
+  "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp. \
   --type=A \
   --ttl=2100 \
   "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpc_config.ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp. \
   --type=TXT \
   --ttl=2100 \
   '"grpc_config=[{\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"NoSrvSimpleService\",\"waitForReady\":true}]}]}}]"'
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. \
-  --type=A \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpc_config.ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp. \
+  --type=TXT \
   --ttl=2100 \
-  "1.2.3.4"
+  '"grpc_config=[{\"clientLanguage\":[\"python\"],\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"PythonService\",\"waitForReady\":true}]}]}}]"'
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. \
-  --type=TXT \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp. \
+  --type=A \
   --ttl=2100 \
-  '"grpc_config=[{\"clientLanguage\":[\"python\"],\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"PythonService\",\"waitForReady\":true}]}]}}]"'
+  "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp. \
   --type=A \
   --ttl=2100 \
   "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpc_config.ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp. \
   --type=TXT \
   --ttl=2100 \
   '"grpc_config=[{\"percentage\":0,\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"CppService\",\"waitForReady\":true}]}]}}]"'
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. \
-  --type=A \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpc_config.ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp. \
+  --type=TXT \
   --ttl=2100 \
-  "1.2.3.4"
+  '"grpc_config=[{\"clientLanguage\":[\"go\"],\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"GoService\",\"waitForReady\":true}]}]}},{\"clientLanguage\":[\"c++\"],\"serviceConfig\":{" "\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"CppService\",\"waitForReady\":true}]}]}}]"'
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. \
-  --type=TXT \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp. \
+  --type=A \
   --ttl=2100 \
-  '"grpc_config=[{\"clientLanguage\":[\"go\"],\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"GoService\",\"waitForReady\":true}]}]}},{\"clientLanguage\":[\"c++\"],\"serviceConfig\":{" "\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"CppService\",\"waitForReady\":true}]}]}}]"'
+  "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp. \
   --type=A \
   --ttl=2100 \
   "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpc_config.ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp. \
   --type=TXT \
   --ttl=2100 \
   '"grpc_config=[{\"percentage\":0,\"serviceConfig\":{\"loadBalancingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"NeverPickedService\",\"waitForReady\":true}]}]}},{\"percentage\":100,\"serviceConfig\":{\"loadBalanc" "ingPolicy\":\"round_robin\",\"methodConfig\":[{\"name\":[{\"method\":\"Foo\",\"service\":\"AlwaysPickedService\",\"waitForReady\":true}]}]}}]"'
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=_grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. \
   --type=SRV \
   --ttl=2100 \
-  "0 0 1234 balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp."
+  "0 0 1234 balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp."
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. \
   --type=A \
   --ttl=2100 \
   "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. \
   --type=A \
   --ttl=2100 \
   "1.2.3.4"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=_grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=_grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. \
   --type=SRV \
   --ttl=2100 \
-  "0 0 1234 balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp."
+  "0 0 1234 balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp."
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. \
   --type=AAAA \
   --ttl=2100 \
   "2607:f8b0:400a:801::1002"
 
 gcloud dns record-sets transaction add \
-  -z=resolver-tests-version-1-grpctestingexp-zone-id \
-  --name=srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. \
+  -z=resolver-tests-version-4-grpctestingexp-zone-id \
+  --name=srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. \
   --type=AAAA \
   --ttl=2100 \
   "2607:f8b0:400a:801::1002"
 
-gcloud dns record-sets transaction describe -z=resolver-tests-version-1-grpctestingexp-zone-id
-gcloud dns record-sets transaction execute -z=resolver-tests-version-1-grpctestingexp-zone-id
-gcloud dns record-sets list -z=resolver-tests-version-1-grpctestingexp-zone-id
+gcloud dns record-sets transaction describe -z=resolver-tests-version-4-grpctestingexp-zone-id
+gcloud dns record-sets transaction execute -z=resolver-tests-version-4-grpctestingexp-zone-id
+gcloud dns record-sets list -z=resolver-tests-version-4-grpctestingexp-zone-id
diff --git a/test/cpp/naming/resolver_component_test.cc b/test/cpp/naming/resolver_component_test.cc
index 94adbcbd35..6f1f0c44b9 100644
--- a/test/cpp/naming/resolver_component_test.cc
+++ b/test/cpp/naming/resolver_component_test.cc
@@ -157,7 +157,7 @@ void ArgsInit(grpc_exec_ctx* exec_ctx, ArgsStruct* args) {
   grpc_pollset_set_add_pollset(exec_ctx, args->pollset_set, args->pollset);
   args->lock = grpc_combiner_create();
   gpr_atm_rel_store(&args->done_atm, 0);
-  args->channel_args = NULL;
+  args->channel_args = nullptr;
 }
 
 void DoNothing(grpc_exec_ctx* exec_ctx, void* arg, grpc_error* error) {}
@@ -167,7 +167,8 @@ void ArgsFinish(grpc_exec_ctx* exec_ctx, ArgsStruct* args) {
   grpc_pollset_set_del_pollset(exec_ctx, args->pollset_set, args->pollset);
   grpc_pollset_set_destroy(exec_ctx, args->pollset_set);
   grpc_closure DoNothing_cb;
-  GRPC_CLOSURE_INIT(&DoNothing_cb, DoNothing, NULL, grpc_schedule_on_exec_ctx);
+  GRPC_CLOSURE_INIT(&DoNothing_cb, DoNothing, nullptr,
+                    grpc_schedule_on_exec_ctx);
   grpc_pollset_shutdown(exec_ctx, args->pollset, &DoNothing_cb);
   // exec_ctx needs to be flushed before calling grpc_pollset_destroy()
   grpc_channel_args_destroy(exec_ctx, args->channel_args);
@@ -194,7 +195,7 @@ void PollPollsetUntilRequestDone(ArgsStruct* args) {
     gpr_log(GPR_DEBUG, "done=%d, time_left=%" PRId64 ".%09d", done,
             time_left.tv_sec, time_left.tv_nsec);
     GPR_ASSERT(gpr_time_cmp(time_left, gpr_time_0(GPR_TIMESPAN)) >= 0);
-    grpc_pollset_worker* worker = NULL;
+    grpc_pollset_worker* worker = nullptr;
     grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
     gpr_mu_lock(args->mu);
     GRPC_LOG_IF_ERROR("pollset_work",
@@ -212,12 +213,12 @@ void CheckServiceConfigResultLocked(grpc_channel_args* channel_args,
   const grpc_arg* service_config_arg =
       grpc_channel_args_find(channel_args, GRPC_ARG_SERVICE_CONFIG);
   if (args->expected_service_config_string != "") {
-    GPR_ASSERT(service_config_arg != NULL);
+    GPR_ASSERT(service_config_arg != nullptr);
     GPR_ASSERT(service_config_arg->type == GRPC_ARG_STRING);
     EXPECT_EQ(service_config_arg->value.string,
               args->expected_service_config_string);
   } else {
-    GPR_ASSERT(service_config_arg == NULL);
+    GPR_ASSERT(service_config_arg == nullptr);
   }
 }
 
@@ -226,11 +227,11 @@ void CheckLBPolicyResultLocked(grpc_channel_args* channel_args,
   const grpc_arg* lb_policy_arg =
       grpc_channel_args_find(channel_args, GRPC_ARG_LB_POLICY_NAME);
   if (args->expected_lb_policy != "") {
-    GPR_ASSERT(lb_policy_arg != NULL);
+    GPR_ASSERT(lb_policy_arg != nullptr);
     GPR_ASSERT(lb_policy_arg->type == GRPC_ARG_STRING);
     EXPECT_EQ(lb_policy_arg->value.string, args->expected_lb_policy);
   } else {
-    GPR_ASSERT(lb_policy_arg == NULL);
+    GPR_ASSERT(lb_policy_arg == nullptr);
   }
 }
 
@@ -240,7 +241,7 @@ void CheckResolverResultLocked(grpc_exec_ctx* exec_ctx, void* argsp,
   grpc_channel_args* channel_args = args->channel_args;
   const grpc_arg* channel_arg =
       grpc_channel_args_find(channel_args, GRPC_ARG_LB_ADDRESSES);
-  GPR_ASSERT(channel_arg != NULL);
+  GPR_ASSERT(channel_arg != nullptr);
   GPR_ASSERT(channel_arg->type == GRPC_ARG_POINTER);
   grpc_lb_addresses* addresses =
       (grpc_lb_addresses*)channel_arg->value.pointer.p;
@@ -272,7 +273,7 @@ void CheckResolverResultLocked(grpc_exec_ctx* exec_ctx, void* argsp,
   gpr_atm_rel_store(&args->done_atm, 1);
   gpr_mu_lock(args->mu);
   GRPC_LOG_IF_ERROR("pollset_kick",
-                    grpc_pollset_kick(exec_ctx, args->pollset, NULL));
+                    grpc_pollset_kick(exec_ctx, args->pollset, nullptr));
   gpr_mu_unlock(args->mu);
 }
 
@@ -284,12 +285,12 @@ TEST(ResolverComponentTest, TestResolvesRelevantRecords) {
   args.expected_service_config_string = FLAGS_expected_chosen_service_config;
   args.expected_lb_policy = FLAGS_expected_lb_policy;
   // maybe build the address with an authority
-  char* whole_uri = NULL;
+  char* whole_uri = nullptr;
   GPR_ASSERT(asprintf(&whole_uri, "dns://%s/%s",
                       FLAGS_local_dns_server_address.c_str(),
                       FLAGS_target_name.c_str()));
   // create resolver and resolve
-  grpc_resolver* resolver = grpc_resolver_create(&exec_ctx, whole_uri, NULL,
+  grpc_resolver* resolver = grpc_resolver_create(&exec_ctx, whole_uri, nullptr,
                                                  args.pollset_set, args.lock);
   gpr_free(whole_uri);
   grpc_closure on_resolver_result_changed;
diff --git a/test/cpp/naming/resolver_component_tests_runner.sh b/test/cpp/naming/resolver_component_tests_runner.sh
index 407db5ed66..11a45d72ce 100755
--- a/test/cpp/naming/resolver_component_tests_runner.sh
+++ b/test/cpp/naming/resolver_component_tests_runner.sh
@@ -73,7 +73,7 @@ EXIT_CODE=0
 # in the resolver.
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-single-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -81,7 +81,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-multi-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.5:1234,True;1.2.3.6:1234,True;1.2.3.7:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -89,7 +89,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv6-single-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1001]:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -97,7 +97,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv6-multi-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1003]:1234,True;[2607:f8b0:400a:801::1004]:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -105,7 +105,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -113,7 +113,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"NoSrvSimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -121,7 +121,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -129,7 +129,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -137,7 +137,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"CppService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -145,7 +145,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"AlwaysPickedService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' \
@@ -153,7 +153,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True;1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -161,7 +161,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1002]:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' \
@@ -169,7 +169,7 @@ $FLAGS_test_bin_path \
 wait $! || EXIT_CODE=1
 
 $FLAGS_test_bin_path \
-  --target_name='ipv4-config-causing-fallback-to-tcp.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-config-causing-fallback-to-tcp.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwo","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooThree","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooFour","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooFive","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooSix","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooSeven","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooEight","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooNine","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTen","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooEleven","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='' \
diff --git a/test/cpp/naming/resolver_component_tests_runner_invoker.cc b/test/cpp/naming/resolver_component_tests_runner_invoker.cc
index 7ea005cc1d..0beb27de1b 100644
--- a/test/cpp/naming/resolver_component_tests_runner_invoker.cc
+++ b/test/cpp/naming/resolver_component_tests_runner_invoker.cc
@@ -60,8 +60,8 @@ static void register_sighandler() {
   struct sigaction act;
   memset(&act, 0, sizeof(act));
   act.sa_handler = sighandler;
-  sigaction(SIGINT, &act, NULL);
-  sigaction(SIGTERM, &act, NULL);
+  sigaction(SIGINT, &act, nullptr);
+  sigaction(SIGTERM, &act, nullptr);
 }
 
 namespace {
diff --git a/test/cpp/naming/resolver_gce_integration_tests_runner.sh b/test/cpp/naming/resolver_gce_integration_tests_runner.sh
index b20d18d9d1..091f9efbbd 100755
--- a/test/cpp/naming/resolver_gce_integration_tests_runner.sh
+++ b/test/cpp/naming/resolver_gce_integration_tests_runner.sh
@@ -34,191 +34,191 @@ echo "Sanity check DNS records are resolveable with dig:"
 EXIT_CODE=0
 
 ONE_FAILED=0
-dig SRV _grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig SRV _grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-single-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-single-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-single-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig SRV _grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig SRV _grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-multi-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-multi-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-multi-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig SRV _grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig SRV _grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-single-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig AAAA ipv6-single-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig AAAA ipv6-single-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig AAAA ipv6-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig AAAA ipv6-single-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig SRV _grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig SRV _grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-multi-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig AAAA ipv6-multi-target.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig AAAA ipv6-multi-target.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig AAAA ipv6-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig AAAA ipv6-multi-target.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig TXT srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig TXT _grpc_config.srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig TXT srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig TXT _grpc_config.srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig SRV _grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig SRV _grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig TXT ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig TXT _grpc_config.ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig TXT ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig TXT _grpc_config.ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig TXT _grpc_config.ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig TXT _grpc_config.ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig TXT ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig TXT ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig TXT ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig TXT _grpc_config.ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig TXT ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig TXT _grpc_config.ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig TXT _grpc_config.ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig TXT _grpc_config.ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig TXT ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig TXT ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig TXT ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig TXT _grpc_config.ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig TXT ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig TXT _grpc_config.ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig SRV _grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig SRV _grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A balancer-for-ipv4-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig A srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig A srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig A srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig A srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig SRV _grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig SRV _grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig SRV _grpclb._tcp.srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig AAAA balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig AAAA balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig AAAA balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig AAAA balancer-for-ipv6-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
 ONE_FAILED=0
-dig AAAA srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
+dig AAAA srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. | grep 'ANSWER SECTION' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Sanity check: dig AAAA srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Sanity check: dig AAAA srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   exit 1
 fi
 
@@ -226,133 +226,133 @@ echo "Sanity check PASSED. Run resolver tests:"
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-single-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: srv-ipv4-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: srv-ipv4-single-target.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-multi-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.5:1234,True;1.2.3.6:1234,True;1.2.3.7:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: srv-ipv4-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: srv-ipv4-multi-target.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv6-single-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1001]:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: srv-ipv6-single-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: srv-ipv6-single-target.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv6-multi-target.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1003]:1234,True;[2607:f8b0:400a:801::1004]:1234,True' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: srv-ipv6-multi-target.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: srv-ipv6-multi-target.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: srv-ipv4-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: srv-ipv4-simple-service-config.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"NoSrvSimpleService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: ipv4-no-srv-simple-service-config.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: ipv4-no-srv-simple-service-config.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: ipv4-no-config-for-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: ipv4-no-config-for-cpp.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: ipv4-cpp-config-has-zero-percentage.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: ipv4-cpp-config-has-zero-percentage.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"CppService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: ipv4-second-language-is-cpp.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: ipv4-second-language-is-cpp.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:443,False' \
   --expected_chosen_service_config='{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"AlwaysPickedService","waitForReady":true}]}]}' \
   --expected_lb_policy='round_robin' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: ipv4-config-with-percentages.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: ipv4-config-with-percentages.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='1.2.3.4:1234,True;1.2.3.4:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: srv-ipv4-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
 ONE_FAILED=0
 bins/$CONFIG/resolver_component_test \
-  --target_name='srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp.' \
+  --target_name='srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp.' \
   --expected_addrs='[2607:f8b0:400a:801::1002]:1234,True;[2607:f8b0:400a:801::1002]:443,False' \
   --expected_chosen_service_config='' \
   --expected_lb_policy='' || ONE_FAILED=1
 if [[ "$ONE_FAILED" != 0 ]]; then
-  echo "Test based on target record: srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-1.grpctestingexp. FAILED"
+  echo "Test based on target record: srv-ipv6-target-has-backend-and-balancer.resolver-tests-version-4.grpctestingexp. FAILED"
   EXIT_CODE=1
 fi
 
diff --git a/test/cpp/naming/resolver_test_record_groups.yaml b/test/cpp/naming/resolver_test_record_groups.yaml
index 2b3204335c..6c4f89d09b 100644
--- a/test/cpp/naming/resolver_test_record_groups.yaml
+++ b/test/cpp/naming/resolver_test_record_groups.yaml
@@ -1,4 +1,4 @@
-resolver_tests_common_zone_name: resolver-tests-version-1.grpctestingexp.
+resolver_tests_common_zone_name: resolver-tests-version-4.grpctestingexp.
 resolver_component_tests:
 - expected_addrs:
   - {address: '1.2.3.4:1234', is_balancer: true}
@@ -58,7 +58,7 @@ resolver_component_tests:
     - {TTL: '2100', data: 0 0 1234 ipv4-simple-service-config, type: SRV}
     ipv4-simple-service-config:
     - {TTL: '2100', data: 1.2.3.4, type: A}
-    srv-ipv4-simple-service-config:
+    _grpc_config.srv-ipv4-simple-service-config:
     - {TTL: '2100', data: 'grpc_config=[{"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]}]}}]',
       type: TXT}
 - expected_addrs:
@@ -69,6 +69,7 @@ resolver_component_tests:
   records:
     ipv4-no-srv-simple-service-config:
     - {TTL: '2100', data: 1.2.3.4, type: A}
+    _grpc_config.ipv4-no-srv-simple-service-config:
     - {TTL: '2100', data: 'grpc_config=[{"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"NoSrvSimpleService","waitForReady":true}]}]}}]',
       type: TXT}
 - expected_addrs:
@@ -79,6 +80,7 @@ resolver_component_tests:
   records:
     ipv4-no-config-for-cpp:
     - {TTL: '2100', data: 1.2.3.4, type: A}
+    _grpc_config.ipv4-no-config-for-cpp:
     - {TTL: '2100', data: 'grpc_config=[{"clientLanguage":["python"],"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"PythonService","waitForReady":true}]}]}}]',
       type: TXT}
 - expected_addrs:
@@ -89,6 +91,7 @@ resolver_component_tests:
   records:
     ipv4-cpp-config-has-zero-percentage:
     - {TTL: '2100', data: 1.2.3.4, type: A}
+    _grpc_config.ipv4-cpp-config-has-zero-percentage:
     - {TTL: '2100', data: 'grpc_config=[{"percentage":0,"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"CppService","waitForReady":true}]}]}}]',
       type: TXT}
 - expected_addrs:
@@ -99,6 +102,7 @@ resolver_component_tests:
   records:
     ipv4-second-language-is-cpp:
     - {TTL: '2100', data: 1.2.3.4, type: A}
+    _grpc_config.ipv4-second-language-is-cpp:
     - {TTL: '2100', data: 'grpc_config=[{"clientLanguage":["go"],"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"GoService","waitForReady":true}]}]}},{"clientLanguage":["c++"],"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"CppService","waitForReady":true}]}]}}]',
       type: TXT}
 - expected_addrs:
@@ -109,6 +113,7 @@ resolver_component_tests:
   records:
     ipv4-config-with-percentages:
     - {TTL: '2100', data: 1.2.3.4, type: A}
+    _grpc_config.ipv4-config-with-percentages:
     - {TTL: '2100', data: 'grpc_config=[{"percentage":0,"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"NeverPickedService","waitForReady":true}]}]}},{"percentage":100,"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"AlwaysPickedService","waitForReady":true}]}]}}]',
       type: TXT}
 - expected_addrs:
@@ -145,5 +150,6 @@ resolver_component_tests:
   records:
     ipv4-config-causing-fallback-to-tcp:
     - {TTL: '2100', data: 1.2.3.4, type: A}
+    _grpc_config.ipv4-config-causing-fallback-to-tcp:
     - {TTL: '2100', data: 'grpc_config=[{"serviceConfig":{"loadBalancingPolicy":"round_robin","methodConfig":[{"name":[{"method":"Foo","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwo","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooThree","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooFour","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooFive","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooSix","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooSeven","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooEight","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooNine","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTen","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooEleven","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]},{"name":[{"method":"FooTwelve","service":"SimpleService","waitForReady":true}]}]}}]',
       type: TXT}
diff --git a/test/cpp/performance/writes_per_rpc_test.cc b/test/cpp/performance/writes_per_rpc_test.cc
index 6c23245021..1c6f44dd7d 100644
--- a/test/cpp/performance/writes_per_rpc_test.cc
+++ b/test/cpp/performance/writes_per_rpc_test.cc
@@ -89,7 +89,7 @@ class EndpointPairFixture {
       const grpc_channel_args* server_args =
           grpc_server_get_channel_args(server_->c_server());
       grpc_transport* transport = grpc_create_chttp2_transport(
-          &exec_ctx, server_args, endpoints.server, 0 /* is_client */);
+          &exec_ctx, server_args, endpoints.server, false /* is_client */);
 
       grpc_pollset** pollsets;
       size_t num_pollsets = 0;
@@ -100,8 +100,9 @@ class EndpointPairFixture {
       }
 
       grpc_server_setup_transport(&exec_ctx, server_->c_server(), transport,
-                                  NULL, server_args);
-      grpc_chttp2_transport_start_reading(&exec_ctx, transport, NULL);
+                                  nullptr, server_args);
+      grpc_chttp2_transport_start_reading(&exec_ctx, transport, nullptr,
+                                          nullptr);
     }
 
     /* create channel */
@@ -111,12 +112,13 @@ class EndpointPairFixture {
       ApplyCommonChannelArguments(&args);
 
       grpc_channel_args c_args = args.c_channel_args();
-      grpc_transport* transport =
-          grpc_create_chttp2_transport(&exec_ctx, &c_args, endpoints.client, 1);
+      grpc_transport* transport = grpc_create_chttp2_transport(
+          &exec_ctx, &c_args, endpoints.client, true);
       GPR_ASSERT(transport);
       grpc_channel* channel = grpc_channel_create(
           &exec_ctx, "target", &c_args, GRPC_CLIENT_DIRECT_CHANNEL, transport);
-      grpc_chttp2_transport_start_reading(&exec_ctx, transport, NULL);
+      grpc_chttp2_transport_start_reading(&exec_ctx, transport, nullptr,
+                                          nullptr);
 
       channel_ = CreateChannelInternal("", channel);
     }
diff --git a/test/cpp/qps/BUILD b/test/cpp/qps/BUILD
index 0d91d52f22..f1abb19e64 100644
--- a/test/cpp/qps/BUILD
+++ b/test/cpp/qps/BUILD
@@ -106,7 +106,7 @@ grpc_cc_library(
         "histogram.h",
         "stats.h",
     ],
-    deps = ["//:gpr"],
+    deps = ["//test/core/util:grpc_test_util"],
 )
 
 grpc_cc_test(
diff --git a/test/cpp/qps/client_async.cc b/test/cpp/qps/client_async.cc
index f7cdfc2bd7..07888214e7 100644
--- a/test/cpp/qps/client_async.cc
+++ b/test/cpp/qps/client_async.cc
@@ -236,6 +236,22 @@ class AsyncClient : public ClientImpl<StubType, RequestType> {
     this->EndThreads();  // this needed for resolution
   }
 
+  ClientRpcContext* ProcessTag(size_t thread_idx, void* tag) {
+    ClientRpcContext* ctx = ClientRpcContext::detag(tag);
+    if (shutdown_state_[thread_idx]->shutdown) {
+      ctx->TryCancel();
+      delete ctx;
+      bool ok;
+      while (cli_cqs_[cq_[thread_idx]]->Next(&tag, &ok)) {
+        ctx = ClientRpcContext::detag(tag);
+        ctx->TryCancel();
+        delete ctx;
+      }
+      return nullptr;
+    }
+    return ctx;
+  }
+
   void ThreadFunc(size_t thread_idx, Client::Thread* t) override final {
     void* got_tag;
     bool ok;
@@ -245,9 +261,13 @@ class AsyncClient : public ClientImpl<StubType, RequestType> {
     if (!cli_cqs_[cq_[thread_idx]]->Next(&got_tag, &ok)) {
       return;
     }
-    ClientRpcContext* ctx = ClientRpcContext::detag(got_tag);
     std::mutex* shutdown_mu = &shutdown_state_[thread_idx]->mutex;
     shutdown_mu->lock();
+    ClientRpcContext* ctx = ProcessTag(thread_idx, got_tag);
+    if (ctx == nullptr) {
+      shutdown_mu->unlock();
+      return;
+    }
     while (cli_cqs_[cq_[thread_idx]]->DoThenAsyncNext(
         [&, ctx, ok, entry_ptr, shutdown_mu]() {
           if (!ctx->RunNextState(ok, entry_ptr)) {
@@ -260,19 +280,9 @@ class AsyncClient : public ClientImpl<StubType, RequestType> {
         },
         &got_tag, &ok, gpr_inf_future(GPR_CLOCK_REALTIME))) {
       t->UpdateHistogram(entry_ptr);
-      // Got a regular event, so process it
-      ctx = ClientRpcContext::detag(got_tag);
-      // Proceed while holding a lock to make sure that
-      // this thread isn't supposed to shut down
       shutdown_mu->lock();
-      if (shutdown_state_[thread_idx]->shutdown) {
-        ctx->TryCancel();
-        delete ctx;
-        while (cli_cqs_[cq_[thread_idx]]->Next(&got_tag, &ok)) {
-          ctx = ClientRpcContext::detag(got_tag);
-          ctx->TryCancel();
-          delete ctx;
-        }
+      ctx = ProcessTag(thread_idx, got_tag);
+      if (ctx == nullptr) {
         shutdown_mu->unlock();
         return;
       }
diff --git a/test/cpp/qps/client_sync.cc b/test/cpp/qps/client_sync.cc
index 9f20b148eb..82a3f0042d 100644
--- a/test/cpp/qps/client_sync.cc
+++ b/test/cpp/qps/client_sync.cc
@@ -60,21 +60,20 @@ class SynchronousClient
     SetupLoadTest(config, num_threads_);
   }
 
-  virtual ~SynchronousClient(){};
+  virtual ~SynchronousClient() {}
 
-  virtual void InitThreadFuncImpl(size_t thread_idx) = 0;
+  virtual bool InitThreadFuncImpl(size_t thread_idx) = 0;
   virtual bool ThreadFuncImpl(HistogramEntry* entry, size_t thread_idx) = 0;
 
   void ThreadFunc(size_t thread_idx, Thread* t) override {
-    InitThreadFuncImpl(thread_idx);
+    if (!InitThreadFuncImpl(thread_idx)) {
+      return;
+    }
     for (;;) {
       // run the loop body
       HistogramEntry entry;
       const bool thread_still_ok = ThreadFuncImpl(&entry, thread_idx);
       t->UpdateHistogram(&entry);
-      if (!thread_still_ok) {
-        gpr_log(GPR_ERROR, "Finishing client thread due to RPC error");
-      }
       if (!thread_still_ok || ThreadCompleted()) {
         return;
       }
@@ -109,9 +108,6 @@ class SynchronousClient
 
   size_t num_threads_;
   std::vector<SimpleResponse> responses_;
-
- private:
-  void DestroyMultithreading() override final { EndThreads(); }
 };
 
 class SynchronousUnaryClient final : public SynchronousClient {
@@ -122,7 +118,7 @@ class SynchronousUnaryClient final : public SynchronousClient {
   }
   ~SynchronousUnaryClient() {}
 
-  void InitThreadFuncImpl(size_t thread_idx) override {}
+  bool InitThreadFuncImpl(size_t thread_idx) override { return true; }
 
   bool ThreadFuncImpl(HistogramEntry* entry, size_t thread_idx) override {
     if (!WaitToIssue(thread_idx)) {
@@ -140,6 +136,9 @@ class SynchronousUnaryClient final : public SynchronousClient {
     entry->set_status(s.error_code());
     return true;
   }
+
+ private:
+  void DestroyMultithreading() override final { EndThreads(); }
 };
 
 template <class StreamType>
@@ -149,31 +148,30 @@ class SynchronousStreamingClient : public SynchronousClient {
       : SynchronousClient(config),
         context_(num_threads_),
         stream_(num_threads_),
+        stream_mu_(num_threads_),
+        shutdown_(num_threads_),
         messages_per_stream_(config.messages_per_stream()),
         messages_issued_(num_threads_) {
     StartThreads(num_threads_);
   }
   virtual ~SynchronousStreamingClient() {
-    std::vector<std::thread> cleanup_threads;
-    for (size_t i = 0; i < num_threads_; i++) {
-      cleanup_threads.emplace_back([this, i]() {
-        auto stream = &stream_[i];
-        if (*stream) {
-          // forcibly cancel the streams, then finish
-          context_[i].TryCancel();
-          (*stream)->Finish().IgnoreError();
-          // don't log any error message on !ok since this was canceled
-        }
-      });
-    }
-    for (auto& th : cleanup_threads) {
-      th.join();
-    }
+    CleanupAllStreams([this](size_t thread_idx) {
+      // Don't log any kind of error since we may have canceled this
+      stream_[thread_idx]->Finish().IgnoreError();
+    });
   }
 
  protected:
   std::vector<grpc::ClientContext> context_;
   std::vector<std::unique_ptr<StreamType>> stream_;
+  // stream_mu_ is only needed when changing an element of stream_ or context_
+  std::vector<std::mutex> stream_mu_;
+  // use struct Bool rather than bool because vector<bool> is not concurrent
+  struct Bool {
+    bool val;
+    Bool() : val(false) {}
+  };
+  std::vector<Bool> shutdown_;
   const int messages_per_stream_;
   std::vector<int> messages_issued_;
 
@@ -182,27 +180,26 @@ class SynchronousStreamingClient : public SynchronousClient {
     // don't set the value since the stream is failed and shouldn't be timed
     entry->set_status(s.error_code());
     if (!s.ok()) {
-      gpr_log(GPR_ERROR, "Stream %" PRIuPTR " received an error %s", thread_idx,
-              s.error_message().c_str());
+      std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+      if (!shutdown_[thread_idx].val) {
+        gpr_log(GPR_ERROR, "Stream %" PRIuPTR " received an error %s",
+                thread_idx, s.error_message().c_str());
+      }
     }
+    // Lock the stream_mu_ now because the client context could change
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
     context_[thread_idx].~ClientContext();
     new (&context_[thread_idx]) ClientContext();
   }
-};
 
-class SynchronousStreamingPingPongClient final
-    : public SynchronousStreamingClient<
-          grpc::ClientReaderWriter<SimpleRequest, SimpleResponse>> {
- public:
-  SynchronousStreamingPingPongClient(const ClientConfig& config)
-      : SynchronousStreamingClient(config) {}
-  ~SynchronousStreamingPingPongClient() {
+  void CleanupAllStreams(std::function<void(size_t)> cleaner) {
     std::vector<std::thread> cleanup_threads;
     for (size_t i = 0; i < num_threads_; i++) {
-      cleanup_threads.emplace_back([this, i]() {
-        auto stream = &stream_[i];
-        if (*stream) {
-          (*stream)->WritesDone();
+      cleanup_threads.emplace_back([this, i, cleaner] {
+        std::lock_guard<std::mutex> l(stream_mu_[i]);
+        shutdown_[i].val = true;
+        if (stream_[i]) {
+          cleaner(i);
         }
       });
     }
@@ -211,10 +208,36 @@ class SynchronousStreamingPingPongClient final
     }
   }
 
-  void InitThreadFuncImpl(size_t thread_idx) override {
+ private:
+  void DestroyMultithreading() override final {
+    CleanupAllStreams(
+        [this](size_t thread_idx) { context_[thread_idx].TryCancel(); });
+    EndThreads();
+  }
+};
+
+class SynchronousStreamingPingPongClient final
+    : public SynchronousStreamingClient<
+          grpc::ClientReaderWriter<SimpleRequest, SimpleResponse>> {
+ public:
+  SynchronousStreamingPingPongClient(const ClientConfig& config)
+      : SynchronousStreamingClient(config) {}
+  ~SynchronousStreamingPingPongClient() {
+    CleanupAllStreams(
+        [this](size_t thread_idx) { stream_[thread_idx]->WritesDone(); });
+  }
+
+ private:
+  bool InitThreadFuncImpl(size_t thread_idx) override {
     auto* stub = channels_[thread_idx % channels_.size()].get_stub();
-    stream_[thread_idx] = stub->StreamingCall(&context_[thread_idx]);
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+    if (!shutdown_[thread_idx].val) {
+      stream_[thread_idx] = stub->StreamingCall(&context_[thread_idx]);
+    } else {
+      return false;
+    }
     messages_issued_[thread_idx] = 0;
+    return true;
   }
 
   bool ThreadFuncImpl(HistogramEntry* entry, size_t thread_idx) override {
@@ -239,7 +262,13 @@ class SynchronousStreamingPingPongClient final
     stream_[thread_idx]->WritesDone();
     FinishStream(entry, thread_idx);
     auto* stub = channels_[thread_idx % channels_.size()].get_stub();
-    stream_[thread_idx] = stub->StreamingCall(&context_[thread_idx]);
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+    if (!shutdown_[thread_idx].val) {
+      stream_[thread_idx] = stub->StreamingCall(&context_[thread_idx]);
+    } else {
+      stream_[thread_idx].reset();
+      return false;
+    }
     messages_issued_[thread_idx] = 0;
     return true;
   }
@@ -251,25 +280,24 @@ class SynchronousStreamingFromClientClient final
   SynchronousStreamingFromClientClient(const ClientConfig& config)
       : SynchronousStreamingClient(config), last_issue_(num_threads_) {}
   ~SynchronousStreamingFromClientClient() {
-    std::vector<std::thread> cleanup_threads;
-    for (size_t i = 0; i < num_threads_; i++) {
-      cleanup_threads.emplace_back([this, i]() {
-        auto stream = &stream_[i];
-        if (*stream) {
-          (*stream)->WritesDone();
-        }
-      });
-    }
-    for (auto& th : cleanup_threads) {
-      th.join();
-    }
+    CleanupAllStreams(
+        [this](size_t thread_idx) { stream_[thread_idx]->WritesDone(); });
   }
 
-  void InitThreadFuncImpl(size_t thread_idx) override {
+ private:
+  std::vector<double> last_issue_;
+
+  bool InitThreadFuncImpl(size_t thread_idx) override {
     auto* stub = channels_[thread_idx % channels_.size()].get_stub();
-    stream_[thread_idx] = stub->StreamingFromClient(&context_[thread_idx],
-                                                    &responses_[thread_idx]);
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+    if (!shutdown_[thread_idx].val) {
+      stream_[thread_idx] = stub->StreamingFromClient(&context_[thread_idx],
+                                                      &responses_[thread_idx]);
+    } else {
+      return false;
+    }
     last_issue_[thread_idx] = UsageTimer::Now();
+    return true;
   }
 
   bool ThreadFuncImpl(HistogramEntry* entry, size_t thread_idx) override {
@@ -287,13 +315,16 @@ class SynchronousStreamingFromClientClient final
     stream_[thread_idx]->WritesDone();
     FinishStream(entry, thread_idx);
     auto* stub = channels_[thread_idx % channels_.size()].get_stub();
-    stream_[thread_idx] = stub->StreamingFromClient(&context_[thread_idx],
-                                                    &responses_[thread_idx]);
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+    if (!shutdown_[thread_idx].val) {
+      stream_[thread_idx] = stub->StreamingFromClient(&context_[thread_idx],
+                                                      &responses_[thread_idx]);
+    } else {
+      stream_[thread_idx].reset();
+      return false;
+    }
     return true;
   }
-
- private:
-  std::vector<double> last_issue_;
 };
 
 class SynchronousStreamingFromServerClient final
@@ -301,12 +332,24 @@ class SynchronousStreamingFromServerClient final
  public:
   SynchronousStreamingFromServerClient(const ClientConfig& config)
       : SynchronousStreamingClient(config), last_recv_(num_threads_) {}
-  void InitThreadFuncImpl(size_t thread_idx) override {
+  ~SynchronousStreamingFromServerClient() {}
+
+ private:
+  std::vector<double> last_recv_;
+
+  bool InitThreadFuncImpl(size_t thread_idx) override {
     auto* stub = channels_[thread_idx % channels_.size()].get_stub();
-    stream_[thread_idx] =
-        stub->StreamingFromServer(&context_[thread_idx], request_);
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+    if (!shutdown_[thread_idx].val) {
+      stream_[thread_idx] =
+          stub->StreamingFromServer(&context_[thread_idx], request_);
+    } else {
+      return false;
+    }
     last_recv_[thread_idx] = UsageTimer::Now();
+    return true;
   }
+
   bool ThreadFuncImpl(HistogramEntry* entry, size_t thread_idx) override {
     GPR_TIMER_SCOPE("SynchronousStreamingFromServerClient::ThreadFunc", 0);
     if (stream_[thread_idx]->Read(&responses_[thread_idx])) {
@@ -317,13 +360,16 @@ class SynchronousStreamingFromServerClient final
     }
     FinishStream(entry, thread_idx);
     auto* stub = channels_[thread_idx % channels_.size()].get_stub();
-    stream_[thread_idx] =
-        stub->StreamingFromServer(&context_[thread_idx], request_);
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+    if (!shutdown_[thread_idx].val) {
+      stream_[thread_idx] =
+          stub->StreamingFromServer(&context_[thread_idx], request_);
+    } else {
+      stream_[thread_idx].reset();
+      return false;
+    }
     return true;
   }
-
- private:
-  std::vector<double> last_recv_;
 };
 
 class SynchronousStreamingBothWaysClient final
@@ -333,24 +379,22 @@ class SynchronousStreamingBothWaysClient final
   SynchronousStreamingBothWaysClient(const ClientConfig& config)
       : SynchronousStreamingClient(config) {}
   ~SynchronousStreamingBothWaysClient() {
-    std::vector<std::thread> cleanup_threads;
-    for (size_t i = 0; i < num_threads_; i++) {
-      cleanup_threads.emplace_back([this, i]() {
-        auto stream = &stream_[i];
-        if (*stream) {
-          (*stream)->WritesDone();
-        }
-      });
-    }
-    for (auto& th : cleanup_threads) {
-      th.join();
-    }
+    CleanupAllStreams(
+        [this](size_t thread_idx) { stream_[thread_idx]->WritesDone(); });
   }
 
-  void InitThreadFuncImpl(size_t thread_idx) override {
+ private:
+  bool InitThreadFuncImpl(size_t thread_idx) override {
     auto* stub = channels_[thread_idx % channels_.size()].get_stub();
-    stream_[thread_idx] = stub->StreamingBothWays(&context_[thread_idx]);
+    std::lock_guard<std::mutex> l(stream_mu_[thread_idx]);
+    if (!shutdown_[thread_idx].val) {
+      stream_[thread_idx] = stub->StreamingBothWays(&context_[thread_idx]);
+    } else {
+      return false;
+    }
+    return true;
   }
+
   bool ThreadFuncImpl(HistogramEntry* entry, size_t thread_idx) override {
     // TODO (vjpai): Do this
     return true;
diff --git a/test/cpp/qps/histogram.h b/test/cpp/qps/histogram.h
index e31d5d78a8..ba72b5b332 100644
--- a/test/cpp/qps/histogram.h
+++ b/test/cpp/qps/histogram.h
@@ -19,8 +19,8 @@
 #ifndef TEST_QPS_HISTOGRAM_H
 #define TEST_QPS_HISTOGRAM_H
 
-#include <grpc/support/histogram.h>
 #include "src/proto/grpc/testing/stats.pb.h"
+#include "test/core/util/histogram.h"
 
 namespace grpc {
 namespace testing {
@@ -29,36 +29,36 @@ class Histogram {
  public:
   // TODO: look into making histogram params not hardcoded for C++
   Histogram()
-      : impl_(gpr_histogram_create(default_resolution(),
-                                   default_max_possible())) {}
+      : impl_(grpc_histogram_create(default_resolution(),
+                                    default_max_possible())) {}
   ~Histogram() {
-    if (impl_) gpr_histogram_destroy(impl_);
+    if (impl_) grpc_histogram_destroy(impl_);
   }
   Histogram(Histogram&& other) : impl_(other.impl_) { other.impl_ = nullptr; }
 
-  void Merge(const Histogram& h) { gpr_histogram_merge(impl_, h.impl_); }
-  void Add(double value) { gpr_histogram_add(impl_, value); }
+  void Merge(const Histogram& h) { grpc_histogram_merge(impl_, h.impl_); }
+  void Add(double value) { grpc_histogram_add(impl_, value); }
   double Percentile(double pctile) const {
-    return gpr_histogram_percentile(impl_, pctile);
+    return grpc_histogram_percentile(impl_, pctile);
   }
-  double Count() const { return gpr_histogram_count(impl_); }
+  double Count() const { return grpc_histogram_count(impl_); }
   void Swap(Histogram* other) { std::swap(impl_, other->impl_); }
   void FillProto(HistogramData* p) {
     size_t n;
-    const auto* data = gpr_histogram_get_contents(impl_, &n);
+    const auto* data = grpc_histogram_get_contents(impl_, &n);
     for (size_t i = 0; i < n; i++) {
       p->add_bucket(data[i]);
     }
-    p->set_min_seen(gpr_histogram_minimum(impl_));
-    p->set_max_seen(gpr_histogram_maximum(impl_));
-    p->set_sum(gpr_histogram_sum(impl_));
-    p->set_sum_of_squares(gpr_histogram_sum_of_squares(impl_));
-    p->set_count(gpr_histogram_count(impl_));
+    p->set_min_seen(grpc_histogram_minimum(impl_));
+    p->set_max_seen(grpc_histogram_maximum(impl_));
+    p->set_sum(grpc_histogram_sum(impl_));
+    p->set_sum_of_squares(grpc_histogram_sum_of_squares(impl_));
+    p->set_count(grpc_histogram_count(impl_));
   }
   void MergeProto(const HistogramData& p) {
-    gpr_histogram_merge_contents(impl_, &*p.bucket().begin(), p.bucket_size(),
-                                 p.min_seen(), p.max_seen(), p.sum(),
-                                 p.sum_of_squares(), p.count());
+    grpc_histogram_merge_contents(impl_, &*p.bucket().begin(), p.bucket_size(),
+                                  p.min_seen(), p.max_seen(), p.sum(),
+                                  p.sum_of_squares(), p.count());
   }
 
   static double default_resolution() { return 0.01; }
@@ -68,7 +68,7 @@ class Histogram {
   Histogram(const Histogram&);
   Histogram& operator=(const Histogram&);
 
-  gpr_histogram* impl_;
+  grpc_histogram* impl_;
 };
 }  // namespace testing
 }  // namespace grpc
diff --git a/test/cpp/qps/json_run_localhost.cc b/test/cpp/qps/json_run_localhost.cc
index 4b788eae73..db8b2a3943 100644
--- a/test/cpp/qps/json_run_localhost.cc
+++ b/test/cpp/qps/json_run_localhost.cc
@@ -46,7 +46,7 @@ std::string as_string(const T& val) {
 
 static void sighandler(int sig) {
   const int errno_saved = errno;
-  if (g_driver != NULL) g_driver->Interrupt();
+  if (g_driver != nullptr) g_driver->Interrupt();
   for (int i = 0; i < kNumWorkers; ++i) {
     if (g_workers[i]) g_workers[i]->Interrupt();
   }
@@ -58,8 +58,8 @@ static void register_sighandler() {
   memset(&act, 0, sizeof(act));
   act.sa_handler = sighandler;
 
-  sigaction(SIGINT, &act, NULL);
-  sigaction(SIGTERM, &act, NULL);
+  sigaction(SIGINT, &act, nullptr);
+  sigaction(SIGTERM, &act, nullptr);
 }
 
 static void LogStatus(int status, const char* label) {
diff --git a/test/cpp/qps/qps_interarrival_test.cc b/test/cpp/qps/qps_interarrival_test.cc
index 461bf624ce..625b7db426 100644
--- a/test/cpp/qps/qps_interarrival_test.cc
+++ b/test/cpp/qps/qps_interarrival_test.cc
@@ -20,7 +20,7 @@
 #include <iostream>
 
 // Use the C histogram rather than C++ to avoid depending on proto
-#include <grpc/support/histogram.h>
+#include "test/core/util/histogram.h"
 
 #include "test/cpp/qps/interarrival.h"
 #include "test/cpp/util/test_config.h"
@@ -31,21 +31,21 @@ using grpc::testing::RandomDistInterface;
 static void RunTest(RandomDistInterface&& r, int threads, std::string title) {
   InterarrivalTimer timer;
   timer.init(r, threads);
-  gpr_histogram* h(gpr_histogram_create(0.01, 60e9));
+  grpc_histogram* h(grpc_histogram_create(0.01, 60e9));
 
   for (int i = 0; i < 10000000; i++) {
     for (int j = 0; j < threads; j++) {
-      gpr_histogram_add(h, timer.next(j));
+      grpc_histogram_add(h, timer.next(j));
     }
   }
 
   std::cout << title << " Distribution" << std::endl;
   std::cout << "Value, Percentile" << std::endl;
   for (double pct = 0.0; pct < 100.0; pct += 1.0) {
-    std::cout << gpr_histogram_percentile(h, pct) << "," << pct << std::endl;
+    std::cout << grpc_histogram_percentile(h, pct) << "," << pct << std::endl;
   }
 
-  gpr_histogram_destroy(h);
+  grpc_histogram_destroy(h);
 }
 
 using grpc::testing::ExpDist;
diff --git a/test/cpp/qps/qps_json_driver.cc b/test/cpp/qps/qps_json_driver.cc
index 1672527426..b2449da69c 100644
--- a/test/cpp/qps/qps_json_driver.cc
+++ b/test/cpp/qps/qps_json_driver.cc
@@ -181,7 +181,7 @@ static bool QpsDriver() {
   if (scfile) {
     // Read the json data from disk
     FILE* json_file = fopen(FLAGS_scenarios_file.c_str(), "r");
-    GPR_ASSERT(json_file != NULL);
+    GPR_ASSERT(json_file != nullptr);
     fseek(json_file, 0, SEEK_END);
     long len = ftell(json_file);
     char* data = new char[len];
diff --git a/test/cpp/qps/qps_worker.cc b/test/cpp/qps/qps_worker.cc
index c288b03ec5..4c9ab0ea43 100644
--- a/test/cpp/qps/qps_worker.cc
+++ b/test/cpp/qps/qps_worker.cc
@@ -32,12 +32,12 @@
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/cpu.h>
-#include <grpc/support/histogram.h>
 #include <grpc/support/host_port.h>
 #include <grpc/support/log.h>
 
 #include "src/proto/grpc/testing/services.pb.h"
 #include "test/core/util/grpc_profiler.h"
+#include "test/core/util/histogram.h"
 #include "test/cpp/qps/client.h"
 #include "test/cpp/qps/server.h"
 #include "test/cpp/util/create_test_channel.h"
diff --git a/test/cpp/qps/server_async.cc b/test/cpp/qps/server_async.cc
index 23c7e85283..72ae772147 100644
--- a/test/cpp/qps/server_async.cc
+++ b/test/cpp/qps/server_async.cc
@@ -79,7 +79,7 @@ class AsyncQpsServerTest final : public grpc::testing::Server {
     auto port_num = port();
     // Negative port number means inproc server, so no listen port needed
     if (port_num >= 0) {
-      char* server_address = NULL;
+      char* server_address = nullptr;
       gpr_join_host_port(&server_address, "::", port_num);
       builder.AddListeningPort(server_address,
                                Server::CreateServerCredentials(config));
diff --git a/test/cpp/qps/server_sync.cc b/test/cpp/qps/server_sync.cc
index 4ef57bd08b..ea89a30e2e 100644
--- a/test/cpp/qps/server_sync.cc
+++ b/test/cpp/qps/server_sync.cc
@@ -159,7 +159,7 @@ class SynchronousServer final : public grpc::testing::Server {
     auto port_num = port();
     // Negative port number means inproc server, so no listen port needed
     if (port_num >= 0) {
-      char* server_address = NULL;
+      char* server_address = nullptr;
       gpr_join_host_port(&server_address, "::", port_num);
       builder.AddListeningPort(server_address,
                                Server::CreateServerCredentials(config));
diff --git a/test/cpp/thread_manager/thread_manager_test.cc b/test/cpp/thread_manager/thread_manager_test.cc
index af90d44495..8282d46694 100644
--- a/test/cpp/thread_manager/thread_manager_test.cc
+++ b/test/cpp/thread_manager/thread_manager_test.cc
@@ -111,7 +111,7 @@ void ThreadManagerTest::PerformTest() {
 }  // namespace grpc
 
 int main(int argc, char** argv) {
-  std::srand(std::time(NULL));
+  std::srand(std::time(nullptr));
 
   grpc::testing::InitTest(&argc, &argv, true);
   grpc::ThreadManagerTest test_rpc_manager;
diff --git a/test/cpp/util/BUILD b/test/cpp/util/BUILD
index 2559c18c32..19e15b1adf 100644
--- a/test/cpp/util/BUILD
+++ b/test/cpp/util/BUILD
@@ -43,6 +43,7 @@ grpc_cc_library(
         "proto_reflection_descriptor_database.h",
     ],
     deps = [
+        "//:grpc++",
         "//:grpc++_config_proto",
         "//src/proto/grpc/reflection/v1alpha:reflection_proto",
     ],
@@ -135,6 +136,105 @@ grpc_cc_library(
 )
 
 grpc_cc_test(
+    name = "grpc_tool_test",
+    srcs = [
+        "grpc_tool_test.cc",
+    ],
+    deps = [
+        ":grpc_cli_libs",
+	":test_util",
+	"//:grpc++_reflection",
+        "//src/proto/grpc/testing:echo_proto",
+        "//src/proto/grpc/testing:echo_messages_proto",
+	"//test/core/util:grpc_test_util",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
+    name = "byte_buffer_test",
+    srcs = [
+        "byte_buffer_test.cc",
+    ],
+    deps = [
+	":test_util",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
+    name = "slice_test",
+    srcs = [
+        "slice_test.cc",
+    ],
+    deps = [
+	":test_util",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
+    name = "string_ref_test",
+    srcs = [
+        "string_ref_test.cc",
+    ],
+    deps = [
+	"//:grpc++",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
+    name = "time_test",
+    srcs = [
+        "time_test.cc",
+    ],
+    deps = [
+	":test_util",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
+    name = "status_test",
+    srcs = [
+        "status_test.cc",
+    ],
+    deps = [
+	":test_util",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
+    name = "cli_call_test",
+    srcs = [
+        "cli_call_test.cc",
+    ],
+    deps = [
+        ":grpc_cli_libs",
+	":test_util",
+        "//src/proto/grpc/testing:echo_proto",
+	"//test/core/util:grpc_test_util",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
     name = "error_details_test",
     srcs = [
         "error_details_test.cc",
diff --git a/test/cpp/util/grpc_tool.cc b/test/cpp/util/grpc_tool.cc
index cd6084ac6d..a6d08cd83c 100644
--- a/test/cpp/util/grpc_tool.cc
+++ b/test/cpp/util/grpc_tool.cc
@@ -230,7 +230,7 @@ const Command* FindCommand(const grpc::string& name) {
       return &ops[i];
     }
   }
-  return NULL;
+  return nullptr;
 }
 }  // namespace
 
@@ -245,13 +245,13 @@ int GrpcToolMainLib(int argc, const char** argv, const CliCredentials& cred,
   argv += 2;
 
   const Command* cmd = FindCommand(command);
-  if (cmd != NULL) {
+  if (cmd != nullptr) {
     GrpcTool grpc_tool;
     if (argc < cmd->min_args || argc > cmd->max_args) {
       // Force the command to print its usage message
       fprintf(stderr, "\nWrong number of arguments for %s\n", command.c_str());
       grpc_tool.SetPrintCommandMode(1);
-      return cmd->function(&grpc_tool, -1, NULL, cred, callback);
+      return cmd->function(&grpc_tool, -1, nullptr, cred, callback);
     }
     const bool ok = cmd->function(&grpc_tool, argc, argv, cred, callback);
     return ok ? 0 : 1;
@@ -281,11 +281,11 @@ bool GrpcTool::Help(int argc, const char** argv, const CliCredentials& cred,
     Usage("");
   } else {
     const Command* cmd = FindCommand(argv[0]);
-    if (cmd == NULL) {
+    if (cmd == nullptr) {
       Usage("Unknown command '" + grpc::string(argv[0]) + "'");
     }
     SetPrintCommandMode(0);
-    cmd->function(this, -1, NULL, cred, callback);
+    cmd->function(this, -1, nullptr, cred, callback);
   }
   return true;
 }
diff --git a/test/cpp/util/grpc_tool_test.cc b/test/cpp/util/grpc_tool_test.cc
index d0b3d7b81b..1c07b2a8ef 100644
--- a/test/cpp/util/grpc_tool_test.cc
+++ b/test/cpp/util/grpc_tool_test.cc
@@ -395,7 +395,7 @@ TEST_F(GrpcToolTest, CallCommand) {
                                    std::bind(PrintStream, &output_stream,
                                              std::placeholders::_1)));
   // Expected output: "message: \"Hello\""
-  EXPECT_TRUE(NULL !=
+  EXPECT_TRUE(nullptr !=
               strstr(output_stream.str().c_str(), "message: \"Hello\""));
   ShutdownServer();
 }
@@ -421,9 +421,9 @@ TEST_F(GrpcToolTest, CallCommandBatch) {
 
   // Expected output: "message: "Hello0"\nmessage: "Hello1"\nmessage:
   // "Hello2"\n"
-  EXPECT_TRUE(NULL != strstr(output_stream.str().c_str(),
-                             "message: \"Hello0\"\nmessage: "
-                             "\"Hello1\"\nmessage: \"Hello2\"\n"));
+  EXPECT_TRUE(nullptr != strstr(output_stream.str().c_str(),
+                                "message: \"Hello0\"\nmessage: "
+                                "\"Hello1\"\nmessage: \"Hello2\"\n"));
   std::cin.rdbuf(orig);
   ShutdownServer();
 }
@@ -448,8 +448,8 @@ TEST_F(GrpcToolTest, CallCommandBatchWithBadRequest) {
   FLAGS_batch = false;
 
   // Expected output: "message: "Hello0"\nmessage: "Hello2"\n"
-  EXPECT_TRUE(NULL != strstr(output_stream.str().c_str(),
-                             "message: \"Hello0\"\nmessage: \"Hello2\"\n"));
+  EXPECT_TRUE(nullptr != strstr(output_stream.str().c_str(),
+                                "message: \"Hello0\"\nmessage: \"Hello2\"\n"));
   std::cin.rdbuf(orig);
   ShutdownServer();
 }
@@ -473,8 +473,8 @@ TEST_F(GrpcToolTest, CallCommandRequestStream) {
                                              std::placeholders::_1)));
 
   // Expected output: "message: \"Hello0Hello1Hello2\""
-  EXPECT_TRUE(NULL != strstr(output_stream.str().c_str(),
-                             "message: \"Hello0Hello1Hello2\""));
+  EXPECT_TRUE(nullptr != strstr(output_stream.str().c_str(),
+                                "message: \"Hello0Hello1Hello2\""));
   std::cin.rdbuf(orig);
   ShutdownServer();
 }
@@ -498,7 +498,7 @@ TEST_F(GrpcToolTest, CallCommandRequestStreamWithBadRequest) {
                                              std::placeholders::_1)));
 
   // Expected output: "message: \"Hello0Hello2\""
-  EXPECT_TRUE(NULL !=
+  EXPECT_TRUE(nullptr !=
               strstr(output_stream.str().c_str(), "message: \"Hello0Hello2\""));
   std::cin.rdbuf(orig);
   ShutdownServer();
@@ -521,8 +521,8 @@ TEST_F(GrpcToolTest, CallCommandResponseStream) {
   for (int i = 0; i < kServerDefaultResponseStreamsToSend; i++) {
     grpc::string expected_response_text =
         "message: \"Hello" + grpc::to_string(i) + "\"\n";
-    EXPECT_TRUE(NULL != strstr(output_stream.str().c_str(),
-                               expected_response_text.c_str()));
+    EXPECT_TRUE(nullptr != strstr(output_stream.str().c_str(),
+                                  expected_response_text.c_str()));
   }
 
   ShutdownServer();
@@ -547,9 +547,9 @@ TEST_F(GrpcToolTest, CallCommandBidiStream) {
 
   // Expected output: "message: \"Hello0\"\nmessage: \"Hello1\"\nmessage:
   // \"Hello2\"\n\n"
-  EXPECT_TRUE(NULL != strstr(output_stream.str().c_str(),
-                             "message: \"Hello0\"\nmessage: "
-                             "\"Hello1\"\nmessage: \"Hello2\"\n"));
+  EXPECT_TRUE(nullptr != strstr(output_stream.str().c_str(),
+                                "message: \"Hello0\"\nmessage: "
+                                "\"Hello1\"\nmessage: \"Hello2\"\n"));
   std::cin.rdbuf(orig);
   ShutdownServer();
 }
@@ -573,8 +573,8 @@ TEST_F(GrpcToolTest, CallCommandBidiStreamWithBadRequest) {
 
   // Expected output: "message: \"Hello0\"\nmessage: \"Hello1\"\nmessage:
   // \"Hello2\"\n\n"
-  EXPECT_TRUE(NULL != strstr(output_stream.str().c_str(),
-                             "message: \"Hello0\"\nmessage: \"Hello2\"\n"));
+  EXPECT_TRUE(nullptr != strstr(output_stream.str().c_str(),
+                                "message: \"Hello0\"\nmessage: \"Hello2\"\n"));
   std::cin.rdbuf(orig);
 
   ShutdownServer();