1 files changed, 21 insertions, 14 deletions

diff --git a/test/cpp/qps/client_callback.cc b/test/cpp/qps/client_callback.cc
index 00d5853a8e..1880f46d43 100644
--- a/test/cpp/qps/client_callback.cc
+++ b/test/cpp/qps/client_callback.cc
@@ -66,7 +66,10 @@ class CallbackClient
             config, BenchmarkStubCreator) {
     num_threads_ = NumThreads(config);
     rpcs_done_ = 0;
-    SetupLoadTest(config, num_threads_);
+
+    //  Don't divide the fixed load among threads as the user threads
+    //  only bootstrap the RPCs
+    SetupLoadTest(config, 1);
     total_outstanding_rpcs_ =
         config.client_channels() * config.outstanding_rpcs_per_channel();
   }
@@ -87,6 +90,11 @@ class CallbackClient
     }
   }
 
+  gpr_timespec NextIssueTime() {
+    std::lock_guard<std::mutex> l(next_issue_time_mu_);
+    return Client::NextIssueTime(0);
+  }
+
  protected:
   size_t num_threads_;
   size_t total_outstanding_rpcs_;
@@ -108,6 +116,8 @@ class CallbackClient
   }
 
  private:
+  std::mutex next_issue_time_mu_;  // Used by next issue time
+
   int NumThreads(const ClientConfig& config) {
     int num_threads = config.async_client_threads();
     if (num_threads <= 0) {  // Use dynamic sizing
@@ -146,7 +156,7 @@ class CallbackUnaryClient final : public CallbackClient {
   bool ThreadFuncImpl(Thread* t, size_t thread_idx) override {
     for (size_t vector_idx = thread_idx; vector_idx < total_outstanding_rpcs_;
          vector_idx += num_threads_) {
-      ScheduleRpc(t, thread_idx, vector_idx);
+      ScheduleRpc(t, vector_idx);
     }
     return true;
   }
@@ -154,26 +164,26 @@ class CallbackUnaryClient final : public CallbackClient {
   void InitThreadFuncImpl(size_t thread_idx) override { return; }
 
  private:
-  void ScheduleRpc(Thread* t, size_t thread_idx, size_t vector_idx) {
+  void ScheduleRpc(Thread* t, size_t vector_idx) {
     if (!closed_loop_) {
-      gpr_timespec next_issue_time = NextIssueTime(thread_idx);
+      gpr_timespec next_issue_time = NextIssueTime();
       // Start an alarm callback to run the internal callback after
       // next_issue_time
       ctx_[vector_idx]->alarm_.experimental().Set(
-          next_issue_time, [this, t, thread_idx, vector_idx](bool ok) {
-            IssueUnaryCallbackRpc(t, thread_idx, vector_idx);
+          next_issue_time, [this, t, vector_idx](bool ok) {
+            IssueUnaryCallbackRpc(t, vector_idx);
           });
     } else {
-      IssueUnaryCallbackRpc(t, thread_idx, vector_idx);
+      IssueUnaryCallbackRpc(t, vector_idx);
     }
   }
 
-  void IssueUnaryCallbackRpc(Thread* t, size_t thread_idx, size_t vector_idx) {
+  void IssueUnaryCallbackRpc(Thread* t, size_t vector_idx) {
     GPR_TIMER_SCOPE("CallbackUnaryClient::ThreadFunc", 0);
     double start = UsageTimer::Now();
     ctx_[vector_idx]->stub_->experimental_async()->UnaryCall(
         (&ctx_[vector_idx]->context_), &request_, &ctx_[vector_idx]->response_,
-        [this, t, thread_idx, start, vector_idx](grpc::Status s) {
+        [this, t, start, vector_idx](grpc::Status s) {
           // Update Histogram with data from the callback run
           HistogramEntry entry;
           if (s.ok()) {
@@ -190,7 +200,7 @@ class CallbackUnaryClient final : public CallbackClient {
             ctx_[vector_idx].reset(
                 new CallbackClientRpcContext(ctx_[vector_idx]->stub_));
             // Schedule a new RPC
-            ScheduleRpc(t, thread_idx, vector_idx);
+            ScheduleRpc(t, vector_idx);
           }
         });
   }
@@ -287,7 +297,7 @@ class CallbackStreamingPingPongReactor final
     if (client_->ThreadCompleted()) return;
 
     if (!client_->IsClosedLoop()) {
-      gpr_timespec next_issue_time = client_->NextIssueTime(thread_idx_);
+      gpr_timespec next_issue_time = client_->NextIssueTime();
       // Start an alarm callback to run the internal callback after
       // next_issue_time
       ctx_->alarm_.experimental().Set(next_issue_time,
@@ -298,11 +308,9 @@ class CallbackStreamingPingPongReactor final
   }
 
   void set_thread_ptr(void* ptr) { thread_ptr_ = ptr; }
-  void set_thread_idx(int thread_idx) { thread_idx_ = thread_idx; }
 
   CallbackStreamingPingPongClient* client_;
   std::unique_ptr<CallbackClientRpcContext> ctx_;
-  int thread_idx_;       // Needed to update histogram entries
   void* thread_ptr_;     // Needed to update histogram entries
   double start_;         // Track message start time
   int messages_issued_;  // Messages issued by this stream
@@ -323,7 +331,6 @@ class CallbackStreamingPingPongClientImpl final
     for (size_t vector_idx = thread_idx; vector_idx < total_outstanding_rpcs_;
          vector_idx += num_threads_) {
       reactor_[vector_idx]->set_thread_ptr(t);
-      reactor_[vector_idx]->set_thread_idx(thread_idx);
       reactor_[vector_idx]->ScheduleRpc();
     }
     return true;