merge

56 files changed, 539 insertions, 174 deletions

diff --git a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
index bb9217d843..087b4076e2 100644
--- a/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.c
@@ -1544,6 +1544,7 @@ static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
     grpc_byte_buffer_reader bbr;
     grpc_byte_buffer_reader_init(&bbr, glb_policy->lb_response_payload);
     grpc_slice response_slice = grpc_byte_buffer_reader_readall(&bbr);
+    grpc_byte_buffer_reader_destroy(&bbr);
     grpc_byte_buffer_destroy(glb_policy->lb_response_payload);
 
     grpc_grpclb_initial_response *response = NULL;
diff --git a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c
index a7f7e9542c..a63bdd933d 100644
--- a/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/filters/client_channel/lb_policy/round_robin/round_robin.c
@@ -811,19 +811,30 @@ static void rr_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
     sc_args.args = new_args;
     grpc_subchannel *subchannel = grpc_client_channel_factory_create_subchannel(
         exec_ctx, args->client_channel_factory, &sc_args);
+    grpc_channel_args_destroy(exec_ctx, new_args);
+    grpc_error *error;
+    // Get the connectivity state of the subchannel. Already existing ones may
+    // be in a state other than INIT.
+    const grpc_connectivity_state subchannel_connectivity_state =
+        grpc_subchannel_check_connectivity(subchannel, &error);
+    if (error != GRPC_ERROR_NONE) {
+      // The subchannel is in error (e.g. shutting down). Ignore it.
+      GRPC_SUBCHANNEL_UNREF(exec_ctx, subchannel, "new_sc_connectivity_error");
+      GRPC_ERROR_UNREF(error);
+      continue;
+    }
     if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
       char *address_uri =
           grpc_sockaddr_to_uri(&addresses->addresses[i].address);
       gpr_log(
           GPR_DEBUG,
           "[RR %p] index %lu: Created subchannel %p for address uri %s into "
-          "subchannel_list %p",
+          "subchannel_list %p. Connectivity state %s",
           (void *)p, (unsigned long)subchannel_index, (void *)subchannel,
-          address_uri, (void *)subchannel_list);
+          address_uri, (void *)subchannel_list,
+          grpc_connectivity_state_name(subchannel_connectivity_state));
       gpr_free(address_uri);
     }
-    grpc_channel_args_destroy(exec_ctx, new_args);
-
     subchannel_data *sd = &subchannel_list->subchannels[subchannel_index++];
     sd->subchannel_list = subchannel_list;
     sd->subchannel = subchannel;
@@ -835,7 +846,7 @@ static void rr_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
      * won't be referring to this value again and it'll be overwritten after
      * the first call to rr_connectivity_changed_locked */
     sd->prev_connectivity_state = GRPC_CHANNEL_INIT;
-    sd->curr_connectivity_state = GRPC_CHANNEL_IDLE;
+    sd->curr_connectivity_state = subchannel_connectivity_state;
     sd->user_data_vtable = addresses->user_data_vtable;
     if (sd->user_data_vtable != NULL) {
       sd->user_data =
diff --git a/src/core/ext/transport/chttp2/transport/flow_control.c b/src/core/ext/transport/chttp2/transport/flow_control.c
index 8dbdd1290a..cec99f6fb6 100644
--- a/src/core/ext/transport/chttp2/transport/flow_control.c
+++ b/src/core/ext/transport/chttp2/transport/flow_control.c
@@ -482,8 +482,8 @@ grpc_chttp2_flowctl_action grpc_chttp2_flowctl_get_bdp_action(
     double bw_dbl = -1;
     if (grpc_bdp_estimator_get_bw(&tfc->bdp_estimator, &bw_dbl)) {
       // we target the max of BDP or bandwidth in microseconds.
-      int32_t frame_size =
-          GPR_CLAMP(GPR_MAX((int32_t)bw_dbl / 1000, bdp), 16384, 16777215);
+      int32_t frame_size = (int32_t)GPR_CLAMP(
+          GPR_MAX((int32_t)bw_dbl / 1000, bdp), 16384, 16777215);
       grpc_chttp2_flowctl_urgency frame_size_urgency = delta_is_significant(
           tfc, frame_size, GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE);
       if (frame_size_urgency != GRPC_CHTTP2_FLOWCTL_NO_ACTION_NEEDED) {
diff --git a/src/core/lib/iomgr/ev_epoll1_linux.c b/src/core/lib/iomgr/ev_epoll1_linux.c
index 6fc3f46cf4..c4ba3b77f3 100644
--- a/src/core/lib/iomgr/ev_epoll1_linux.c
+++ b/src/core/lib/iomgr/ev_epoll1_linux.c
@@ -457,7 +457,14 @@ static void pollset_init(grpc_pollset *pollset, gpr_mu **mu) {
   gpr_mu_init(&pollset->mu);
   *mu = &pollset->mu;
   pollset->neighbourhood = &g_neighbourhoods[choose_neighbourhood()];
+  pollset->reassigning_neighbourhood = false;
+  pollset->root_worker = NULL;
+  pollset->kicked_without_poller = false;
   pollset->seen_inactive = true;
+  pollset->shutting_down = false;
+  pollset->shutdown_closure = NULL;
+  pollset->begin_refs = 0;
+  pollset->next = pollset->prev = NULL;
 }
 
 static void pollset_destroy(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) {
@@ -489,6 +496,7 @@ static void pollset_destroy(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset) {
 }
 
 static grpc_error *pollset_kick_all(grpc_pollset *pollset) {
+  GPR_TIMER_BEGIN("pollset_kick_all", 0);
   grpc_error *error = GRPC_ERROR_NONE;
   if (pollset->root_worker != NULL) {
     grpc_pollset_worker *worker = pollset->root_worker;
@@ -514,7 +522,7 @@ static grpc_error *pollset_kick_all(grpc_pollset *pollset) {
   }
   // TODO: sreek.  Check if we need to set 'kicked_without_poller' to true here
   // in the else case
-
+  GPR_TIMER_END("pollset_kick_all", 0);
   return error;
 }
 
@@ -522,6 +530,7 @@ static void pollset_maybe_finish_shutdown(grpc_exec_ctx *exec_ctx,
                                           grpc_pollset *pollset) {
   if (pollset->shutdown_closure != NULL && pollset->root_worker == NULL &&
       pollset->begin_refs == 0) {
+    GPR_TIMER_MARK("pollset_finish_shutdown", 0);
     GRPC_CLOSURE_SCHED(exec_ctx, pollset->shutdown_closure, GRPC_ERROR_NONE);
     pollset->shutdown_closure = NULL;
   }
@@ -529,12 +538,14 @@ static void pollset_maybe_finish_shutdown(grpc_exec_ctx *exec_ctx,
 
 static void pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                              grpc_closure *closure) {
+  GPR_TIMER_BEGIN("pollset_shutdown", 0);
   GPR_ASSERT(pollset->shutdown_closure == NULL);
   GPR_ASSERT(!pollset->shutting_down);
   pollset->shutdown_closure = closure;
   pollset->shutting_down = true;
   GRPC_LOG_IF_ERROR("pollset_shutdown", pollset_kick_all(pollset));
   pollset_maybe_finish_shutdown(exec_ctx, pollset);
+  GPR_TIMER_END("pollset_shutdown", 0);
 }
 
 static int poll_deadline_to_millis_timeout(gpr_timespec deadline,
@@ -568,6 +579,7 @@ static grpc_error *process_epoll_events(grpc_exec_ctx *exec_ctx,
   static const char *err_desc = "process_events";
   grpc_error *error = GRPC_ERROR_NONE;
 
+  GPR_TIMER_BEGIN("process_epoll_events", 0);
   for (int idx = 0; (idx < MAX_EPOLL_EVENTS_HANDLED_PER_ITERATION) &&
                     g_epoll_set.cursor != g_epoll_set.num_events;
        idx++) {
@@ -593,7 +605,7 @@ static grpc_error *process_epoll_events(grpc_exec_ctx *exec_ctx,
       }
     }
   }
-
+  GPR_TIMER_END("process_epoll_events", 0);
   return error;
 }
 
@@ -606,6 +618,8 @@ static grpc_error *process_epoll_events(grpc_exec_ctx *exec_ctx,
    no need for any synchronization when accesing fields in g_epoll_set */
 static grpc_error *do_epoll_wait(grpc_exec_ctx *exec_ctx, grpc_pollset *ps,
                                  gpr_timespec now, gpr_timespec deadline) {
+  GPR_TIMER_BEGIN("do_epoll_wait", 0);
+
   int r;
   int timeout = poll_deadline_to_millis_timeout(deadline, now);
   if (timeout != 0) {
@@ -628,12 +642,14 @@ static grpc_error *do_epoll_wait(grpc_exec_ctx *exec_ctx, grpc_pollset *ps,
   g_epoll_set.num_events = r;
   g_epoll_set.cursor = 0;
 
+  GPR_TIMER_END("do_epoll_wait", 0);
   return GRPC_ERROR_NONE;
 }
 
 static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
                          grpc_pollset_worker **worker_hdl, gpr_timespec *now,
                          gpr_timespec deadline) {
+  GPR_TIMER_BEGIN("begin_worker", 0);
   if (worker_hdl != NULL) *worker_hdl = worker;
   worker->initialized_cv = false;
   SET_KICK_STATE(worker, UNKICKED);
@@ -738,14 +754,17 @@ static bool begin_worker(grpc_pollset *pollset, grpc_pollset_worker *worker,
 
   if (pollset->kicked_without_poller) {
     pollset->kicked_without_poller = false;
+    GPR_TIMER_END("begin_worker", 0);
     return false;
   }
 
+  GPR_TIMER_END("begin_worker", 0);
   return worker->kick_state == DESIGNATED_POLLER && !pollset->shutting_down;
 }
 
 static bool check_neighbourhood_for_available_poller(
     pollset_neighbourhood *neighbourhood) {
+  GPR_TIMER_BEGIN("check_neighbourhood_for_available_poller", 0);
   bool found_worker = false;
   do {
     grpc_pollset *inspect = neighbourhood->active_root;
@@ -767,6 +786,7 @@ static bool check_neighbourhood_for_available_poller(
               }
               SET_KICK_STATE(inspect_worker, DESIGNATED_POLLER);
               if (inspect_worker->initialized_cv) {
+                GPR_TIMER_MARK("signal worker", 0);
                 gpr_cv_signal(&inspect_worker->cv);
               }
             } else {
@@ -802,12 +822,14 @@ static bool check_neighbourhood_for_available_poller(
     }
     gpr_mu_unlock(&inspect->mu);
   } while (!found_worker);
+  GPR_TIMER_END("check_neighbourhood_for_available_poller", 0);
   return found_worker;
 }
 
 static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                        grpc_pollset_worker *worker,
                        grpc_pollset_worker **worker_hdl) {
+  GPR_TIMER_BEGIN("end_worker", 0);
   if (GRPC_TRACER_ON(grpc_polling_trace)) {
     gpr_log(GPR_DEBUG, "PS:%p END_WORKER:%p", pollset, worker);
   }
@@ -877,6 +899,7 @@ static void end_worker(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
     pollset_maybe_finish_shutdown(exec_ctx, pollset);
   }
   GPR_ASSERT(gpr_atm_no_barrier_load(&g_active_poller) != (gpr_atm)worker);
+  GPR_TIMER_END("end_worker", 0);
 }
 
 /* pollset->po.mu lock must be held by the caller before calling this.
@@ -889,8 +912,10 @@ static grpc_error *pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *ps,
   grpc_pollset_worker worker;
   grpc_error *error = GRPC_ERROR_NONE;
   static const char *err_desc = "pollset_work";
-  if (ps->kicked_without_poller) {
-    ps->kicked_without_poller = false;
+  GPR_TIMER_BEGIN("pollset_work", 0);
+  if (pollset->kicked_without_poller) {
+    pollset->kicked_without_poller = false;
+    GPR_TIMER_END("pollset_work", 0);
     return GRPC_ERROR_NONE;
   }
 
@@ -931,11 +956,14 @@ static grpc_error *pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *ps,
   end_worker(exec_ctx, ps, &worker, worker_hdl);
 
   gpr_tls_set(&g_current_thread_pollset, 0);
+  GPR_TIMER_END("pollset_work", 0);
   return error;
 }
 
 static grpc_error *pollset_kick(grpc_pollset *pollset,
                                 grpc_pollset_worker *specific_worker) {
+  GPR_TIMER_BEGIN("pollset_kick", 0);
+  grpc_error *ret_err = GRPC_ERROR_NONE;
   if (GRPC_TRACER_ON(grpc_polling_trace)) {
     gpr_strvec log;
     gpr_strvec_init(&log);
@@ -970,7 +998,7 @@ static grpc_error *pollset_kick(grpc_pollset *pollset,
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_ERROR, " .. kicked_without_poller");
         }
-        return GRPC_ERROR_NONE;
+        goto done;
       }
       grpc_pollset_worker *next_worker = root_worker->next;
       if (root_worker->kick_state == KICKED) {
@@ -978,13 +1006,13 @@ static grpc_error *pollset_kick(grpc_pollset *pollset,
           gpr_log(GPR_ERROR, " .. already kicked %p", root_worker);
         }
         SET_KICK_STATE(root_worker, KICKED);
-        return GRPC_ERROR_NONE;
+        goto done;
       } else if (next_worker->kick_state == KICKED) {
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_ERROR, " .. already kicked %p", next_worker);
         }
         SET_KICK_STATE(next_worker, KICKED);
-        return GRPC_ERROR_NONE;
+        goto done;
       } else if (root_worker ==
                      next_worker &&  // only try and wake up a poller if
                                      // there is no next worker
@@ -994,7 +1022,8 @@ static grpc_error *pollset_kick(grpc_pollset *pollset,
           gpr_log(GPR_ERROR, " .. kicked %p", root_worker);
         }
         SET_KICK_STATE(root_worker, KICKED);
-        return grpc_wakeup_fd_wakeup(&global_wakeup_fd);
+        ret_err = grpc_wakeup_fd_wakeup(&global_wakeup_fd);
+        goto done;
       } else if (next_worker->kick_state == UNKICKED) {
         if (GRPC_TRACER_ON(grpc_polling_trace)) {
           gpr_log(GPR_ERROR, " .. kicked %p", next_worker);
@@ -1002,7 +1031,7 @@ static grpc_error *pollset_kick(grpc_pollset *pollset,
         GPR_ASSERT(next_worker->initialized_cv);
         SET_KICK_STATE(next_worker, KICKED);
         gpr_cv_signal(&next_worker->cv);
-        return GRPC_ERROR_NONE;
+        goto done;
       } else if (next_worker->kick_state == DESIGNATED_POLLER) {
         if (root_worker->kick_state != DESIGNATED_POLLER) {
           if (GRPC_TRACER_ON(grpc_polling_trace)) {
@@ -1015,59 +1044,64 @@ static grpc_error *pollset_kick(grpc_pollset *pollset,
           if (root_worker->initialized_cv) {
             gpr_cv_signal(&root_worker->cv);
           }
-          return GRPC_ERROR_NONE;
+          goto done;
         } else {
           if (GRPC_TRACER_ON(grpc_polling_trace)) {
             gpr_log(GPR_ERROR, " .. non-root poller %p (root=%p)", next_worker,
                     root_worker);
           }
           SET_KICK_STATE(next_worker, KICKED);
-          return grpc_wakeup_fd_wakeup(&global_wakeup_fd);
+          ret_err = grpc_wakeup_fd_wakeup(&global_wakeup_fd);
+          goto done;
         }
       } else {
         GPR_ASSERT(next_worker->kick_state == KICKED);
         SET_KICK_STATE(next_worker, KICKED);
-        return GRPC_ERROR_NONE;
+        goto done;
       }
     } else {
       if (GRPC_TRACER_ON(grpc_polling_trace)) {
         gpr_log(GPR_ERROR, " .. kicked while waking up");
       }
-      return GRPC_ERROR_NONE;
+      goto done;
     }
   } else if (specific_worker->kick_state == KICKED) {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_ERROR, " .. specific worker already kicked");
     }
-    return GRPC_ERROR_NONE;
+    goto done;
   } else if (gpr_tls_get(&g_current_thread_worker) ==
              (intptr_t)specific_worker) {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_ERROR, " .. mark %p kicked", specific_worker);
     }
     SET_KICK_STATE(specific_worker, KICKED);
-    return GRPC_ERROR_NONE;
+    goto done;
   } else if (specific_worker ==
              (grpc_pollset_worker *)gpr_atm_no_barrier_load(&g_active_poller)) {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_ERROR, " .. kick active poller");
     }
     SET_KICK_STATE(specific_worker, KICKED);
-    return grpc_wakeup_fd_wakeup(&global_wakeup_fd);
+    ret_err = grpc_wakeup_fd_wakeup(&global_wakeup_fd);
+    goto done;
   } else if (specific_worker->initialized_cv) {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_ERROR, " .. kick waiting worker");
     }
     SET_KICK_STATE(specific_worker, KICKED);
     gpr_cv_signal(&specific_worker->cv);
-    return GRPC_ERROR_NONE;
+    goto done;
   } else {
     if (GRPC_TRACER_ON(grpc_polling_trace)) {
       gpr_log(GPR_ERROR, " .. kick non-waiting worker");
     }
     SET_KICK_STATE(specific_worker, KICKED);
-    return GRPC_ERROR_NONE;
+    goto done;
   }
+done:
+  GPR_TIMER_END("pollset_kick", 0);
+  return ret_err;
 }
 
 static void pollset_add_fd(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
@@ -1149,8 +1183,6 @@ static const grpc_event_engine_vtable vtable = {
  * Create epoll_fd (epoll_set_init() takes care of that) to make sure epoll
  * support is available */
 const grpc_event_engine_vtable *grpc_init_epoll1_linux(bool explicit_request) {
-  /* TODO(sreek): Temporarily disable this poller unless explicitly requested
-   * via GRPC_POLL_STRATEGY */
   if (!explicit_request) {
     return NULL;
   }
diff --git a/src/core/lib/security/credentials/jwt/jwt_verifier.c b/src/core/lib/security/credentials/jwt/jwt_verifier.c
index 6cd558d123..a27284bc50 100644
--- a/src/core/lib/security/credentials/jwt/jwt_verifier.c
+++ b/src/core/lib/security/credentials/jwt/jwt_verifier.c
@@ -442,7 +442,7 @@ static EVP_PKEY *extract_pkey_from_x509(const char *x509_str) {
 
 end:
   BIO_free(bio);
-  if (x509 != NULL) X509_free(x509);
+  X509_free(x509);
   return result;
 }
 
@@ -496,6 +496,8 @@ static EVP_PKEY *pkey_from_jwk(grpc_exec_ctx *exec_ctx, const grpc_json *json,
   const grpc_json *key_prop;
   RSA *rsa = NULL;
   EVP_PKEY *result = NULL;
+  BIGNUM *tmp_n = NULL;
+  BIGNUM *tmp_e = NULL;
 
   GPR_ASSERT(kty != NULL && json != NULL);
   if (strcmp(kty, "RSA") != 0) {
@@ -507,8 +509,6 @@ static EVP_PKEY *pkey_from_jwk(grpc_exec_ctx *exec_ctx, const grpc_json *json,
     gpr_log(GPR_ERROR, "Could not create rsa key.");
     goto end;
   }
-  BIGNUM *tmp_n = NULL;
-  BIGNUM *tmp_e = NULL;
   for (key_prop = json->child; key_prop != NULL; key_prop = key_prop->next) {
     if (strcmp(key_prop->key, "n") == 0) {
       tmp_n =
@@ -528,11 +528,16 @@ static EVP_PKEY *pkey_from_jwk(grpc_exec_ctx *exec_ctx, const grpc_json *json,
     gpr_log(GPR_ERROR, "Cannot set RSA key from inputs.");
     goto end;
   }
+  /* RSA_set0_key takes ownership on success. */
+  tmp_n = NULL;
+  tmp_e = NULL;
   result = EVP_PKEY_new();
   EVP_PKEY_set1_RSA(result, rsa); /* uprefs rsa. */
 
 end:
-  if (rsa != NULL) RSA_free(rsa);
+  RSA_free(rsa);
+  BN_free(tmp_n);
+  BN_free(tmp_e);
   return result;
 }
 
@@ -618,7 +623,7 @@ static int verify_jwt_signature(EVP_PKEY *key, const char *alg,
   result = 1;
 
 end:
-  if (md_ctx != NULL) EVP_MD_CTX_destroy(md_ctx);
+  EVP_MD_CTX_destroy(md_ctx);
   return result;
 }
 
@@ -658,7 +663,7 @@ static void on_keys_retrieved(grpc_exec_ctx *exec_ctx, void *user_data,
 
 end:
   if (json != NULL) grpc_json_destroy(json);
-  if (verification_key != NULL) EVP_PKEY_free(verification_key);
+  EVP_PKEY_free(verification_key);
   ctx->user_cb(exec_ctx, ctx->user_data, status, claims);
   verifier_cb_ctx_destroy(exec_ctx, ctx);
 }
diff --git a/src/core/lib/security/credentials/oauth2/oauth2_credentials.c b/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
index c59e55136c..10b270c49c 100644
--- a/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
+++ b/src/core/lib/security/credentials/oauth2/oauth2_credentials.c
@@ -296,10 +296,10 @@ static bool oauth2_token_fetcher_get_request_metadata(
   gpr_mu_unlock(&c->mu);
   if (start_fetch) {
     grpc_call_credentials_ref(creds);
-    c->fetch_func(exec_ctx, grpc_credentials_metadata_request_create(creds),
-                  &c->httpcli_context, &c->pollent,
-                  on_oauth2_token_fetcher_http_response,
-                  gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), refresh_threshold));
+    c->fetch_func(
+        exec_ctx, grpc_credentials_metadata_request_create(creds),
+        &c->httpcli_context, &c->pollent, on_oauth2_token_fetcher_http_response,
+        gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC), refresh_threshold));
   }
   return false;
 }
diff --git a/src/core/lib/surface/version.c b/src/core/lib/surface/version.c
index 8cef15da80..96c16105e7 100644
--- a/src/core/lib/surface/version.c
+++ b/src/core/lib/surface/version.c
@@ -23,4 +23,4 @@
 
 const char *grpc_version_string(void) { return "4.0.0-dev"; }
 
-const char *grpc_g_stands_for(void) { return "gregarious"; }
+const char *grpc_g_stands_for(void) { return "gambit"; }
diff --git a/src/cpp/common/version_cc.cc b/src/cpp/common/version_cc.cc
index 34558ea216..2e9a51316d 100644
--- a/src/cpp/common/version_cc.cc
+++ b/src/cpp/common/version_cc.cc
@@ -22,5 +22,5 @@
 #include <grpc++/grpc++.h>
 
 namespace grpc {
-grpc::string Version() { return "1.5.0-dev"; }
+grpc::string Version() { return "1.7.0-dev"; }
 }
diff --git a/src/csharp/Grpc.Core.Tests/NUnitMain.cs b/src/csharp/Grpc.Core.Tests/NUnitMain.cs
index 87972e23ad..49cb8cd3b9 100644
--- a/src/csharp/Grpc.Core.Tests/NUnitMain.cs
+++ b/src/csharp/Grpc.Core.Tests/NUnitMain.cs
@@ -33,7 +33,7 @@ namespace Grpc.Core.Tests
         public static int Main(string[] args)
         {
             // Make logger immune to NUnit capturing stdout and stderr to workaround https://github.com/nunit/nunit/issues/1406.
-            GrpcEnvironment.SetLogger(new TextWriterLogger(Console.Error));
+            GrpcEnvironment.SetLogger(new ConsoleLogger());
 #if NETCOREAPP1_0
             return new AutoRun(typeof(NUnitMain).GetTypeInfo().Assembly).Execute(args, new ExtendedTextWrapper(Console.Out), Console.In);
 #else
diff --git a/src/csharp/Grpc.Core/Grpc.Core.targets b/src/csharp/Grpc.Core/Grpc.Core.targets
index 3367d51a80..cce53db82b 100644
--- a/src/csharp/Grpc.Core/Grpc.Core.targets
+++ b/src/csharp/Grpc.Core/Grpc.Core.targets
@@ -4,26 +4,32 @@
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\win\native\grpc_csharp_ext.x86.dll">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>grpc_csharp_ext.x86.dll</Link>
+      <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\win\native\grpc_csharp_ext.x64.dll">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>grpc_csharp_ext.x64.dll</Link>
+      <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux\native\libgrpc_csharp_ext.x86.so">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x86.so</Link>
+      <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux\native\libgrpc_csharp_ext.x64.so">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x64.so</Link>
+      <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\osx\native\libgrpc_csharp_ext.x86.dylib">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x86.dylib</Link>
+      <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\osx\native\libgrpc_csharp_ext.x64.dylib">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x64.dylib</Link>
+      <Visible>false</Visible>
     </Content>
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/src/csharp/Grpc.Core/GrpcEnvironment.cs b/src/csharp/Grpc.Core/GrpcEnvironment.cs
index cbc7d2078c..80031cb7ef 100644
--- a/src/csharp/Grpc.Core/GrpcEnvironment.cs
+++ b/src/csharp/Grpc.Core/GrpcEnvironment.cs
@@ -43,7 +43,7 @@ namespace Grpc.Core
         static readonly HashSet<Channel> registeredChannels = new HashSet<Channel>();
         static readonly HashSet<Server> registeredServers = new HashSet<Server>();
 
-        static ILogger logger = new NullLogger();
+        static ILogger logger = new LogLevelFilterLogger(new ConsoleLogger(), LogLevel.Off, true);
 
         readonly GrpcThreadPool threadPool;
         readonly DebugStats debugStats = new DebugStats();
diff --git a/src/csharp/Grpc.Core/Internal/AtomicCounter.cs b/src/csharp/Grpc.Core/Internal/AtomicCounter.cs
index 64e16e4c54..20e25f9d88 100644
--- a/src/csharp/Grpc.Core/Internal/AtomicCounter.cs
+++ b/src/csharp/Grpc.Core/Internal/AtomicCounter.cs
@@ -64,7 +64,7 @@ namespace Grpc.Core.Internal
         {
             get
             {
-                return counter;
+                return Interlocked.Read(ref counter);
             }
         }
     }
diff --git a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
index 19b44c2618..3c94b602c0 100644
--- a/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
+++ b/src/csharp/Grpc.Core/Internal/GrpcThreadPool.cs
@@ -33,8 +33,8 @@ namespace Grpc.Core.Internal
     internal class GrpcThreadPool
     {
         static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<GrpcThreadPool>();
-        static readonly WaitCallback RunCompletionQueueEventCallbackSuccess = new WaitCallback((callback) => RunCompletionQueueEventCallback((OpCompletionDelegate) callback, true));
-        static readonly WaitCallback RunCompletionQueueEventCallbackFailure = new WaitCallback((callback) => RunCompletionQueueEventCallback((OpCompletionDelegate) callback, false));
+        const int FinishContinuationsSleepMillis = 10;
+        const int MaxFinishContinuationsSleepTotalMillis = 10000;
 
         readonly GrpcEnvironment environment;
         readonly object myLock = new object();
@@ -42,6 +42,9 @@ namespace Grpc.Core.Internal
         readonly int poolSize;
         readonly int completionQueueCount;
         readonly bool inlineHandlers;
+        readonly WaitCallback runCompletionQueueEventCallbackSuccess;
+        readonly WaitCallback runCompletionQueueEventCallbackFailure;
+        readonly AtomicCounter queuedContinuationCounter = new AtomicCounter();
 
         readonly List<BasicProfiler> threadProfilers = new List<BasicProfiler>();  // profilers assigned to threadpool threads
 
@@ -64,6 +67,9 @@ namespace Grpc.Core.Internal
             this.inlineHandlers = inlineHandlers;
             GrpcPreconditions.CheckArgument(poolSize >= completionQueueCount,
                 "Thread pool size cannot be smaller than the number of completion queues used.");
+
+            this.runCompletionQueueEventCallbackSuccess = new WaitCallback((callback) => RunCompletionQueueEventCallback((OpCompletionDelegate) callback, true));
+            this.runCompletionQueueEventCallbackFailure = new WaitCallback((callback) => RunCompletionQueueEventCallback((OpCompletionDelegate) callback, false));
         }
 
         public void Start()
@@ -173,7 +179,8 @@ namespace Grpc.Core.Internal
                         // Use cached delegates to avoid unnecessary allocations
                         if (!inlineHandlers)
                         {
-                            ThreadPool.QueueUserWorkItem(success ? RunCompletionQueueEventCallbackSuccess : RunCompletionQueueEventCallbackFailure, callback);
+                            queuedContinuationCounter.Increment();
+                            ThreadPool.QueueUserWorkItem(success ? runCompletionQueueEventCallbackSuccess : runCompletionQueueEventCallbackFailure, callback);
                         }
                         else
                         {
@@ -187,6 +194,24 @@ namespace Grpc.Core.Internal
                 }
             }
             while (ev.type != CompletionQueueEvent.CompletionType.Shutdown);
+
+            // Continuations are running on default threadpool that consists of background threads.
+            // GrpcThreadPool thread (a foreground thread) will not exit unless all queued work had
+            // been finished to prevent terminating the continuations queued prematurely.
+            int sleepIterations = 0;
+            while (queuedContinuationCounter.Count != 0)
+            {
+                // Only happens on shutdown and having pending continuations shouldn't very common,
+                // so sleeping here for a little bit is fine.
+                if (sleepIterations >= MaxFinishContinuationsSleepTotalMillis / FinishContinuationsSleepMillis)
+                {
+                    Logger.Warning("Shutting down gRPC thread [{0}] with unfinished callbacks (Timed out waiting for callbacks to finish).",
+                        Thread.CurrentThread.Name);
+                    break;
+                }
+                Thread.Sleep(FinishContinuationsSleepMillis);
+                sleepIterations ++;
+            }
         }
 
         private static IReadOnlyCollection<CompletionQueueSafeHandle> CreateCompletionQueueList(GrpcEnvironment environment, int completionQueueCount)
@@ -200,7 +225,7 @@ namespace Grpc.Core.Internal
             return list.AsReadOnly();
         }
 
-        private static void RunCompletionQueueEventCallback(OpCompletionDelegate callback, bool success)
+        private void RunCompletionQueueEventCallback(OpCompletionDelegate callback, bool success)
         {
             try
             {
@@ -210,6 +235,10 @@ namespace Grpc.Core.Internal
             {
                 Logger.Error(e, "Exception occured while invoking completion delegate");
             }
+            finally
+            {
+                queuedContinuationCounter.Decrement();
+            }
         }
     }
 }
diff --git a/src/csharp/Grpc.Core/Logging/LogLevel.cs b/src/csharp/Grpc.Core/Logging/LogLevel.cs
index 7718e3c2ab..4db0e47b97 100644
--- a/src/csharp/Grpc.Core/Logging/LogLevel.cs
+++ b/src/csharp/Grpc.Core/Logging/LogLevel.cs
@@ -39,6 +39,10 @@ namespace Grpc.Core.Logging
         /// <summary>
         /// Error severity.
         /// </summary>
-        Error
+        Error,
+        /// <summary>
+        /// Logging is off.
+        /// </summary>
+        Off = int.MaxValue
     }
 }
diff --git a/src/csharp/Grpc.Core/Logging/LogLevelFilterLogger.cs b/src/csharp/Grpc.Core/Logging/LogLevelFilterLogger.cs
index b611c191a5..a650d029d7 100644
--- a/src/csharp/Grpc.Core/Logging/LogLevelFilterLogger.cs
+++ b/src/csharp/Grpc.Core/Logging/LogLevelFilterLogger.cs
@@ -27,6 +27,8 @@ namespace Grpc.Core.Logging
     /// <summary>Logger that filters out messages below certain log level.</summary>
     public class LogLevelFilterLogger : ILogger
     {
+        // Verbosity environment variable used by C core.
+        private const string CoreVerbosityEnvVarName = "GRPC_VERBOSITY";
         readonly ILogger innerLogger;
         readonly LogLevel logLevel;
 
@@ -40,6 +42,19 @@ namespace Grpc.Core.Logging
         }
 
         /// <summary>
+        /// Creates and instance of <c>LogLevelFilter.</c>
+        /// The <c>fromEnvironmentVariable</c> parameter allows looking up "GRPC_VERBOSITY" setting provided by C-core
+        /// and uses the same log level for C# logs. Using this setting is recommended as it can prevent unintentionally hiding
+        /// C core logs requested by "GRPC_VERBOSITY" environment variable (which could happen if C# logger's log level was set to a more restrictive value).
+        /// </summary>
+        /// <param name="logger">the logger to forward filtered logs to.</param>
+        /// <param name="defaultLogLevel">the default log level, unless overriden by env variable.</param>
+        /// <param name="fromEnvironmentVariable">if <c>true</c>, override log level with setting from environment variable.</param>
+        public LogLevelFilterLogger(ILogger logger, LogLevel defaultLogLevel, bool fromEnvironmentVariable) : this(logger, GetLogLevelFromEnvironment(defaultLogLevel, fromEnvironmentVariable))
+        {
+        }
+
+        /// <summary>
         /// Returns a logger associated with the specified type.
         /// </summary>
         public virtual ILogger ForType<T>()
@@ -141,5 +156,33 @@ namespace Grpc.Core.Logging
                 innerLogger.Error(exception, message);
             }
         }
+
+        /// <summary>Get log level based on a default and lookup of <c>GRPC_VERBOSITY</c> environment variable.</summary>
+        private static LogLevel GetLogLevelFromEnvironment(LogLevel defaultLogLevel, bool fromEnvironmentVariable)
+        {
+            if (!fromEnvironmentVariable)
+            {
+                return defaultLogLevel;
+            }
+
+            var verbosityString = System.Environment.GetEnvironmentVariable(CoreVerbosityEnvVarName);
+            if (verbosityString == null)
+            {
+                return defaultLogLevel;
+            }
+
+            // NOTE: C core doesn't have "WARNING" log level
+            switch (verbosityString.ToUpperInvariant())
+            {
+                case "DEBUG":
+                    return LogLevel.Debug;
+                case "INFO":
+                    return LogLevel.Info;
+                case "ERROR":
+                    return LogLevel.Error;
+                default:
+                    return defaultLogLevel;
+            }
+        }
     }
 }
diff --git a/src/csharp/Grpc.Core/Version.csproj.include b/src/csharp/Grpc.Core/Version.csproj.include
index 81156452f3..124ecab14c 100755
--- a/src/csharp/Grpc.Core/Version.csproj.include
+++ b/src/csharp/Grpc.Core/Version.csproj.include
@@ -1,7 +1,7 @@
 <!-- This file is generated -->
 <Project>
   <PropertyGroup>
-    <GrpcCsharpVersion>1.5.0-dev</GrpcCsharpVersion>
+    <GrpcCsharpVersion>1.7.0-dev</GrpcCsharpVersion>
     <GoogleProtobufVersion>3.3.0</GoogleProtobufVersion>
   </PropertyGroup>
 </Project>
diff --git a/src/csharp/Grpc.Core/VersionInfo.cs b/src/csharp/Grpc.Core/VersionInfo.cs
index 92aa0e5aed..588cc84516 100644
--- a/src/csharp/Grpc.Core/VersionInfo.cs
+++ b/src/csharp/Grpc.Core/VersionInfo.cs
@@ -33,11 +33,11 @@ namespace Grpc.Core
         /// <summary>
         /// Current <c>AssemblyFileVersion</c> of gRPC C# assemblies
         /// </summary>
-        public const string CurrentAssemblyFileVersion = "1.5.0.0";
+        public const string CurrentAssemblyFileVersion = "1.7.0.0";
 
         /// <summary>
         /// Current version of gRPC C#
         /// </summary>
-        public const string CurrentVersion = "1.5.0-dev";
+        public const string CurrentVersion = "1.7.0-dev";
     }
 }
diff --git a/src/csharp/Grpc.Examples.Tests/NUnitMain.cs b/src/csharp/Grpc.Examples.Tests/NUnitMain.cs
index a83caea206..bcb8b46b64 100644
--- a/src/csharp/Grpc.Examples.Tests/NUnitMain.cs
+++ b/src/csharp/Grpc.Examples.Tests/NUnitMain.cs
@@ -33,7 +33,7 @@ namespace Grpc.Examples.Tests
         public static int Main(string[] args)
         {
             // Make logger immune to NUnit capturing stdout and stderr to workaround https://github.com/nunit/nunit/issues/1406.
-            GrpcEnvironment.SetLogger(new TextWriterLogger(Console.Error));
+            GrpcEnvironment.SetLogger(new ConsoleLogger());
 #if NETCOREAPP1_0
             return new AutoRun(typeof(NUnitMain).GetTypeInfo().Assembly).Execute(args, new ExtendedTextWrapper(Console.Out), Console.In);
 #else
diff --git a/src/csharp/Grpc.HealthCheck.Tests/NUnitMain.cs b/src/csharp/Grpc.HealthCheck.Tests/NUnitMain.cs
index 57deb3ba30..365551e895 100644
--- a/src/csharp/Grpc.HealthCheck.Tests/NUnitMain.cs
+++ b/src/csharp/Grpc.HealthCheck.Tests/NUnitMain.cs
@@ -33,7 +33,7 @@ namespace Grpc.HealthCheck.Tests
         public static int Main(string[] args)
         {
             // Make logger immune to NUnit capturing stdout and stderr to workaround https://github.com/nunit/nunit/issues/1406.
-            GrpcEnvironment.SetLogger(new TextWriterLogger(Console.Error));
+            GrpcEnvironment.SetLogger(new ConsoleLogger());
 #if NETCOREAPP1_0
             return new AutoRun(typeof(NUnitMain).GetTypeInfo().Assembly).Execute(args, new ExtendedTextWrapper(Console.Out), Console.In);
 #else
diff --git a/src/csharp/Grpc.IntegrationTesting/NUnitMain.cs b/src/csharp/Grpc.IntegrationTesting/NUnitMain.cs
index a36802af55..9d24762e0a 100644
--- a/src/csharp/Grpc.IntegrationTesting/NUnitMain.cs
+++ b/src/csharp/Grpc.IntegrationTesting/NUnitMain.cs
@@ -33,7 +33,7 @@ namespace Grpc.IntegrationTesting
         public static int Main(string[] args)
         {
             // Make logger immune to NUnit capturing stdout and stderr to workaround https://github.com/nunit/nunit/issues/1406.
-            GrpcEnvironment.SetLogger(new TextWriterLogger(Console.Error));
+            GrpcEnvironment.SetLogger(new ConsoleLogger());
 #if NETCOREAPP1_0
             return new AutoRun(typeof(NUnitMain).GetTypeInfo().Assembly).Execute(args, new ExtendedTextWrapper(Console.Out), Console.In);
 #else
diff --git a/src/csharp/Grpc.Microbenchmarks/Program.cs b/src/csharp/Grpc.Microbenchmarks/Program.cs
index 8412ba3245..d07d4187c4 100644
--- a/src/csharp/Grpc.Microbenchmarks/Program.cs
+++ b/src/csharp/Grpc.Microbenchmarks/Program.cs
@@ -27,7 +27,7 @@ namespace Grpc.Microbenchmarks
     {
         public static void Main(string[] args)
         {
-            GrpcEnvironment.SetLogger(new TextWriterLogger(Console.Error));
+            GrpcEnvironment.SetLogger(new ConsoleLogger());
             var benchmark = new SendMessageBenchmark();
             benchmark.Init();
             foreach (int threadCount in new int[] {1, 1, 2, 4, 8, 12})
diff --git a/src/csharp/Grpc.Reflection.Tests/NUnitMain.cs b/src/csharp/Grpc.Reflection.Tests/NUnitMain.cs
index a45dab8772..49ed1cc8d4 100644
--- a/src/csharp/Grpc.Reflection.Tests/NUnitMain.cs
+++ b/src/csharp/Grpc.Reflection.Tests/NUnitMain.cs
@@ -33,7 +33,7 @@ namespace Grpc.Reflection.Tests
         public static int Main(string[] args)
         {
             // Make logger immune to NUnit capturing stdout and stderr to workaround https://github.com/nunit/nunit/issues/1406.
-            GrpcEnvironment.SetLogger(new TextWriterLogger(Console.Error));
+            GrpcEnvironment.SetLogger(new ConsoleLogger());
 #if NETCOREAPP1_0
             return new AutoRun(typeof(NUnitMain).GetTypeInfo().Assembly).Execute(args, new ExtendedTextWrapper(Console.Out), Console.In);
 #else
diff --git a/src/csharp/build_packages_dotnetcli.bat b/src/csharp/build_packages_dotnetcli.bat
index 4e3870d71d..c419d87049 100755
--- a/src/csharp/build_packages_dotnetcli.bat
+++ b/src/csharp/build_packages_dotnetcli.bat
@@ -13,7 +13,7 @@
 @rem limitations under the License.
 
 @rem Current package versions
-set VERSION=1.5.0-dev
+set VERSION=1.7.0-dev
 
 @rem Adjust the location of nuget.exe
 set NUGET=C:\nuget\nuget.exe
diff --git a/src/csharp/build_packages_dotnetcli.sh b/src/csharp/build_packages_dotnetcli.sh
index f259cdb1d5..124dfbb257 100755
--- a/src/csharp/build_packages_dotnetcli.sh
+++ b/src/csharp/build_packages_dotnetcli.sh
@@ -39,7 +39,7 @@ dotnet pack --configuration Release Grpc.Auth --output ../../../artifacts
 dotnet pack --configuration Release Grpc.HealthCheck --output ../../../artifacts
 dotnet pack --configuration Release Grpc.Reflection --output ../../../artifacts
 
-nuget pack Grpc.nuspec -Version "1.5.0-dev" -OutputDirectory ../../artifacts
-nuget pack Grpc.Tools.nuspec -Version "1.5.0-dev" -OutputDirectory ../../artifacts
+nuget pack Grpc.nuspec -Version "1.7.0-dev" -OutputDirectory ../../artifacts
+nuget pack Grpc.Tools.nuspec -Version "1.7.0-dev" -OutputDirectory ../../artifacts
 
 (cd ../../artifacts && zip csharp_nugets_dotnetcli.zip *.nupkg)
diff --git a/src/node/health_check/package.json b/src/node/health_check/package.json
index 6aa41522cd..3c7d3707ee 100644
--- a/src/node/health_check/package.json
+++ b/src/node/health_check/package.json
@@ -1,6 +1,6 @@
 {
   "name": "grpc-health-check",
-  "version": "1.5.0-dev",
+  "version": "1.7.0-dev",
   "author": "Google Inc.",
   "description": "Health check service for use with gRPC",
   "repository": {
@@ -15,7 +15,7 @@
     }
   ],
   "dependencies": {
-    "grpc": "^1.5.0-dev",
+    "grpc": "^1.7.0-dev",
     "lodash": "^3.9.3",
     "google-protobuf": "^3.0.0"
   },
diff --git a/src/node/tools/package.json b/src/node/tools/package.json
index 0a3c32734c..d9b1fb86c9 100644
--- a/src/node/tools/package.json
+++ b/src/node/tools/package.json
@@ -1,6 +1,6 @@
 {
   "name": "grpc-tools",
-  "version": "1.5.0-dev",
+  "version": "1.7.0-dev",
   "author": "Google Inc.",
   "description": "Tools for developing with gRPC on Node.js",
   "homepage": "https://grpc.io/",
diff --git a/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec b/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
index 345eecc279..3a282b0526 100644
--- a/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
+++ b/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
@@ -42,7 +42,7 @@ Pod::Spec.new do |s|
   # exclamation mark ensures that other "regular" pods will be able to find it as it'll be installed
   # before them.
   s.name     = '!ProtoCompiler-gRPCPlugin'
-  v = '1.5.0-dev'
+  v = '1.7.0-dev'
   s.version  = v
   s.summary  = 'The gRPC ProtoC plugin generates Objective-C files from .proto services.'
   s.description = <<-DESC
diff --git a/src/objective-c/GRPCClient/GRPCCall+GID.h b/src/objective-c/GRPCClient/GRPCCall+GID.h
new file mode 100644
index 0000000000..3ee732e79e
--- /dev/null
+++ b/src/objective-c/GRPCClient/GRPCCall+GID.h
@@ -0,0 +1,29 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#import "GRPCCall.h"
+#import "GRPCCall+OAuth2.h"
+
+#import <Google/SignIn.h>
+
+/**
+ * Extend GIDSignIn class to comply GRPCAuthorizationProtocol
+ */
+@interface GIDSignIn (GRPC) <GRPCAuthorizationProtocol>
+- (void)getTokenWithHandler:(void (^)(NSString *token))hander;
+@end
diff --git a/src/objective-c/GRPCClient/GRPCCall+GID.m b/src/objective-c/GRPCClient/GRPCCall+GID.m
new file mode 100644
index 0000000000..030737147b
--- /dev/null
+++ b/src/objective-c/GRPCClient/GRPCCall+GID.m
@@ -0,0 +1,28 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#import "GRPCCall+GID.h"
+
+@implementation GIDSignIn (GRPC)
+
+- (void)getTokenWithHandler:(void (^)(NSString *token))handler {
+  NSString *token = self.currentUser.authentication.accessToken;
+  handler(token);
+}
+
+@end
diff --git a/src/objective-c/GRPCClient/GRPCCall+OAuth2.h b/src/objective-c/GRPCClient/GRPCCall+OAuth2.h
index 65465e9523..adb1042aa0 100644
--- a/src/objective-c/GRPCClient/GRPCCall+OAuth2.h
+++ b/src/objective-c/GRPCClient/GRPCCall+OAuth2.h
@@ -18,6 +18,13 @@
 
 #import "GRPCCall.h"
 
+/**
+ * The protocol of an OAuth2 token object from which GRPCCall can acquire a token.
+ */
+@protocol GRPCAuthorizationProtocol
+- (void)getTokenWithHandler:(void (^)(NSString *token))hander;
+@end
+
 /** Helpers for setting and reading headers compatible with OAuth2. */
 @interface GRPCCall (OAuth2)
 
@@ -33,4 +40,12 @@
 /** Returns the value (if any) of the "www-authenticate" response header (the challenge header). */
 @property(atomic, readonly) NSString *oauth2ChallengeHeader;
 
+/**
+ * The authorization token object to be used when starting the call. If the value is set to nil, no
+ * oauth authentication will be used.
+ *
+ * If tokenProvider exists, it takes precedence over the token set by oauth2AccessToken.
+ */
+@property(atomic, strong) id<GRPCAuthorizationProtocol> tokenProvider;
+
 @end
diff --git a/src/objective-c/GRPCClient/GRPCCall+OAuth2.m b/src/objective-c/GRPCClient/GRPCCall+OAuth2.m
index eaa7465087..8451ebe870 100644
--- a/src/objective-c/GRPCClient/GRPCCall+OAuth2.m
+++ b/src/objective-c/GRPCClient/GRPCCall+OAuth2.m
@@ -16,6 +16,8 @@
  *
  */
 
+#import <objc/runtime.h>
+
 #import "GRPCCall+OAuth2.h"
 
 static NSString * const kAuthorizationHeader = @"authorization";
@@ -23,6 +25,7 @@ static NSString * const kBearerPrefix = @"Bearer ";
 static NSString * const kChallengeHeader = @"www-authenticate";
 
 @implementation GRPCCall (OAuth2)
+@dynamic tokenProvider;
 
 - (NSString *)oauth2AccessToken {
   NSString *headerValue = self.requestHeaders[kAuthorizationHeader];
@@ -45,4 +48,12 @@ static NSString * const kChallengeHeader = @"www-authenticate";
   return self.responseHeaders[kChallengeHeader];
 }
 
+- (void)setTokenProvider:(id<GRPCAuthorizationProtocol>)tokenProvider {
+  objc_setAssociatedObject(self, @selector(tokenProvider), tokenProvider, OBJC_ASSOCIATION_RETAIN);
+}
+
+- (id<GRPCAuthorizationProtocol>)tokenProvider {
+  return objc_getAssociatedObject(self, @selector(tokenProvider));
+}
+
 @end
diff --git a/src/objective-c/GRPCClient/GRPCCall.m b/src/objective-c/GRPCClient/GRPCCall.m
index 872362419e..436c19e354 100644
--- a/src/objective-c/GRPCClient/GRPCCall.m
+++ b/src/objective-c/GRPCClient/GRPCCall.m
@@ -18,6 +18,8 @@
 
 #import "GRPCCall.h"
 
+#import "GRPCCall+OAuth2.h"
+
 #include <grpc/grpc.h>
 #include <grpc/support/time.h>
 #import <RxLibrary/GRXConcurrentWriteable.h>
@@ -40,10 +42,14 @@ NSString * const kGRPCHeadersKey = @"io.grpc.HeadersKey";
 NSString * const kGRPCTrailersKey = @"io.grpc.TrailersKey";
 static NSMutableDictionary *callFlags;
 
+static NSString * const kAuthorizationHeader = @"authorization";
+static NSString * const kBearerPrefix = @"Bearer ";
+
 @interface GRPCCall () <GRXWriteable>
 // Make them read-write.
 @property(atomic, strong) NSDictionary *responseHeaders;
 @property(atomic, strong) NSDictionary *responseTrailers;
+@property(atomic) BOOL isWaitingForToken;
 @end
 
 // The following methods of a C gRPC call object aren't reentrant, and thus
@@ -181,9 +187,6 @@ static NSMutableDictionary *callFlags;
 
 - (void)finishWithError:(NSError *)errorOrNil {
   @synchronized(self) {
-    if (_state == GRXWriterStateFinished) {
-      return;
-    }
     _state = GRXWriterStateFinished;
   }
 
@@ -211,7 +214,11 @@ static NSMutableDictionary *callFlags;
   [self finishWithError:[NSError errorWithDomain:kGRPCErrorDomain
                                             code:GRPCErrorCodeCancelled
                                         userInfo:@{NSLocalizedDescriptionKey: @"Canceled by app"}]];
-  [self cancelCall];
+  if (!self.isWaitingForToken) {
+    [self cancelCall];
+  } else {
+    self.isWaitingForToken = NO;
+  }
 }
 
 - (void)dealloc {
@@ -410,22 +417,13 @@ static NSMutableDictionary *callFlags;
 
 #pragma mark GRXWriter implementation
 
-- (void)startWithWriteable:(id<GRXWriteable>)writeable {
-  @synchronized(self) {
-    _state = GRXWriterStateStarted;
-  }
-
-  // Create a retain cycle so that this instance lives until the RPC finishes (or is cancelled).
-  // This makes RPCs in which the call isn't externally retained possible (as long as it is started
-  // before being autoreleased).
-  // Care is taken not to retain self strongly in any of the blocks used in this implementation, so
-  // that the life of the instance is determined by this retain cycle.
-  _retainSelf = self;
-
+- (void)startCallWithWriteable:(id<GRXWriteable>)writeable {
   _responseWriteable = [[GRXConcurrentWriteable alloc] initWithWriteable:writeable
                                                            dispatchQueue:_responseQueue];
 
-  _wrappedCall = [[GRPCWrappedCall alloc] initWithHost:_host serverName:_serverName path:_path];
+  _wrappedCall = [[GRPCWrappedCall alloc] initWithHost:_host
+                                            serverName:_serverName
+                                                  path:_path];
   NSAssert(_wrappedCall, @"Error allocating RPC objects. Low memory?");
 
   [self sendHeaders:_requestHeaders];
@@ -437,20 +435,49 @@ static NSMutableDictionary *callFlags;
     // TODO(jcanizales): Check this on init.
     [NSException raise:NSInvalidArgumentException format:@"host of %@ is nil", _host];
   }
-  __weak typeof(self) weakSelf = self;
   _connectivityMonitor = [GRPCConnectivityMonitor monitorWithHost:host];
+  __weak typeof(self) weakSelf = self;
   void (^handler)() = ^{
     typeof(self) strongSelf = weakSelf;
-    if (strongSelf) {
-      [strongSelf finishWithError:[NSError errorWithDomain:kGRPCErrorDomain
-                                                      code:GRPCErrorCodeUnavailable
-                                                  userInfo:@{ NSLocalizedDescriptionKey : @"Connectivity lost." }]];
-    }
+    [strongSelf finishWithError:[NSError errorWithDomain:kGRPCErrorDomain
+                                                    code:GRPCErrorCodeUnavailable
+                                                userInfo:@{ NSLocalizedDescriptionKey : @"Connectivity lost." }]];
   };
   [_connectivityMonitor handleLossWithHandler:handler
                       wifiStatusChangeHandler:nil];
 }
 
+- (void)startWithWriteable:(id<GRXWriteable>)writeable {
+  @synchronized(self) {
+    _state = GRXWriterStateStarted;
+  }
+
+  // Create a retain cycle so that this instance lives until the RPC finishes (or is cancelled).
+  // This makes RPCs in which the call isn't externally retained possible (as long as it is started
+  // before being autoreleased).
+  // Care is taken not to retain self strongly in any of the blocks used in this implementation, so
+  // that the life of the instance is determined by this retain cycle.
+  _retainSelf = self;
+
+  if (self.tokenProvider != nil) {
+    self.isWaitingForToken = YES;
+    __weak typeof(self) weakSelf = self;
+    [self.tokenProvider getTokenWithHandler:^(NSString *token){
+      typeof(self) strongSelf = weakSelf;
+      if (strongSelf && strongSelf.isWaitingForToken) {
+        if (token) {
+          NSString *t = [kBearerPrefix stringByAppendingString:token];
+          strongSelf.requestHeaders[kAuthorizationHeader] = t;
+        }
+        [strongSelf startCallWithWriteable:writeable];
+        strongSelf.isWaitingForToken = NO;
+      }
+    }];
+  } else {
+    [self startCallWithWriteable:writeable];
+  }
+}
+
 - (void)setState:(GRXWriterState)newState {
   @synchronized(self) {
     // Manual transitions are only allowed from the started or paused states.
diff --git a/src/objective-c/GRPCClient/private/GRPCRequestHeaders.m b/src/objective-c/GRPCClient/private/GRPCRequestHeaders.m
index 7640a64d6d..5de1d8fff5 100644
--- a/src/objective-c/GRPCClient/private/GRPCRequestHeaders.m
+++ b/src/objective-c/GRPCClient/private/GRPCRequestHeaders.m
@@ -103,7 +103,6 @@ static void CheckKeyValuePairIsValid(NSString *key, id value) {
 }
 
 - (void)setObject:(id)obj forKey:(NSString *)key {
-  [self checkCallIsNotStarted];
   CheckIsNonNilASCII(@"Header name", key);
   key = key.lowercaseString;
   CheckKeyValuePairIsValid(key, obj);
diff --git a/src/objective-c/GRPCClient/private/version.h b/src/objective-c/GRPCClient/private/version.h
index d9cb3881e1..843954e84a 100644
--- a/src/objective-c/GRPCClient/private/version.h
+++ b/src/objective-c/GRPCClient/private/version.h
@@ -23,4 +23,4 @@
 // `tools/buildgen/generate_projects.sh`.
 
 
-#define GRPC_OBJC_VERSION_STRING @"1.5.0-dev"
+#define GRPC_OBJC_VERSION_STRING @"1.7.0-dev"
diff --git a/src/objective-c/RxLibrary/GRXConcurrentWriteable.m b/src/objective-c/RxLibrary/GRXConcurrentWriteable.m
index cb5d0a63f0..bbfe491783 100644
--- a/src/objective-c/RxLibrary/GRXConcurrentWriteable.m
+++ b/src/objective-c/RxLibrary/GRXConcurrentWriteable.m
@@ -28,7 +28,7 @@
 @implementation GRXConcurrentWriteable {
   dispatch_queue_t _writeableQueue;
   // This ensures that writesFinishedWithError: is only sent once to the writeable.
-  dispatch_once_t _alreadyFinished;
+  BOOL _alreadyFinished;
 }
 
 - (instancetype)init {
@@ -65,19 +65,35 @@
 
 - (void)enqueueSuccessfulCompletion {
   dispatch_async(_writeableQueue, ^{
-    dispatch_once(&_alreadyFinished, ^{
+    BOOL finished = NO;
+    @synchronized (self) {
+      if (!_alreadyFinished) {
+        _alreadyFinished = YES;
+      } else {
+        finished = YES;
+      }
+    }
+    if (!finished) {
       // Cancellation is now impossible. None of the other three blocks can run concurrently with
       // this one.
       [self.writeable writesFinishedWithError:nil];
       // Skip any possible message to the wrapped writeable enqueued after this one.
       self.writeable = nil;
-    });
+    }
   });
 }
 
 - (void)cancelWithError:(NSError *)error {
   NSAssert(error, @"For a successful completion, use enqueueSuccessfulCompletion.");
-  dispatch_once(&_alreadyFinished, ^{
+  BOOL finished = NO;
+  @synchronized (self) {
+    if (!_alreadyFinished) {
+      _alreadyFinished = YES;
+    } else {
+      finished = YES;
+    }
+  }
+  if (!finished) {
     // Skip any of the still-enqueued messages to the wrapped writeable. We use the atomic setter to
     // nillify writeable because we might be running concurrently with the blocks in
     // _writeableQueue, and assignment with ARC isn't atomic.
@@ -87,15 +103,23 @@
     dispatch_async(_writeableQueue, ^{
       [writeable writesFinishedWithError:error];
     });
-  });
+  }
 }
 
 - (void)cancelSilently {
-  dispatch_once(&_alreadyFinished, ^{
+  BOOL finished = NO;
+  @synchronized (self) {
+    if (!_alreadyFinished) {
+      _alreadyFinished = YES;
+    } else {
+      finished = YES;
+    }
+  }
+  if (!finished) {
     // Skip any of the still-enqueued messages to the wrapped writeable. We use the atomic setter to
     // nillify writeable because we might be running concurrently with the blocks in
     // _writeableQueue, and assignment with ARC isn't atomic.
     self.writeable = nil;
-  });
+  }
 }
 @end
diff --git a/src/objective-c/tests/build_one_example.sh b/src/objective-c/tests/build_one_example.sh
index 298d8e7043..985d55f3cc 100755
--- a/src/objective-c/tests/build_one_example.sh
+++ b/src/objective-c/tests/build_one_example.sh
@@ -37,11 +37,11 @@ rm -f Podfile.lock
 pod install
 
 set -o pipefail
-XCODEBUILD_FILTER='(^===|^\*\*|\bfatal\b|\berror\b|\bwarning\b|\bfail|\bpassed\b)'
+XCODEBUILD_FILTER='(^CompileC |^Ld |^.*clang |^ *cd |^ *export |^Libtool |^.*libtool |^CpHeader |^ *builtin-copy )'
 xcodebuild \
     build \
     -workspace *.xcworkspace \
     -scheme $SCHEME \
     -destination name="iPhone 6" \
-    | egrep "$XCODEBUILD_FILTER" \
-    | egrep -v "(GPBDictionary|GPBArray)" -
+    | egrep -v "$XCODEBUILD_FILTER" \
+    | egrep -v "^$" -
diff --git a/src/objective-c/tests/run_tests.sh b/src/objective-c/tests/run_tests.sh
index 8843edaede..5b7a2d104a 100755
--- a/src/objective-c/tests/run_tests.sh
+++ b/src/objective-c/tests/run_tests.sh
@@ -38,7 +38,7 @@ trap 'kill -9 `jobs -p` ; echo "EXIT TIME:  $(date)"' EXIT
 # element of the pipe fails.
 # TODO(jcanizales): Use xctool instead? Issue #2540.
 set -o pipefail
-XCODEBUILD_FILTER='(^===|^\*\*|\bfatal\b|\berror\b|\bwarning\b|\bfail|\bpassed\b)'
+XCODEBUILD_FILTER='(^CompileC |^Ld |^.*clang |^ *cd |^ *export |^Libtool |^.*libtool |^CpHeader |^ *builtin-copy )'
 echo "TIME:  $(date)"
 xcodebuild \
     -workspace Tests.xcworkspace \
@@ -48,8 +48,8 @@ xcodebuild \
     HOST_PORT_LOCAL=localhost:5050 \
     HOST_PORT_REMOTE=grpc-test.sandbox.googleapis.com \
     test \
-    | egrep "$XCODEBUILD_FILTER" \
-    | egrep -v "(GPBDictionary|GPBArray)" -
+    | egrep -v "$XCODEBUILD_FILTER" \
+    | egrep -v '^$' -
 
 echo "TIME:  $(date)"
 xcodebuild \
@@ -60,16 +60,12 @@ xcodebuild \
     | egrep "$XCODEBUILD_FILTER" \
     | egrep -v "(GPBDictionary|GPBArray)" -
 
-# Temporarily disabled for (possible) flakiness on Jenkins.
-# Fix or reenable after confirmation/disconfirmation that it is the source of
-# Jenkins problem.
-
-# echo "TIME:  $(date)"
-# xcodebuild \
-#     -workspace Tests.xcworkspace \
-#     -scheme CronetUnitTests \
-#     -destination name="iPhone 6" \
-#     test | xcpretty
+echo "TIME:  $(date)"
+xcodebuild \
+    -workspace Tests.xcworkspace \
+    -scheme CronetUnitTests \
+    -destination name="iPhone 6" \
+    test | xcpretty
 
 echo "TIME:  $(date)"
 xcodebuild \
diff --git a/src/php/composer.json b/src/php/composer.json
index c6a74c5c84..3606a18f34 100644
--- a/src/php/composer.json
+++ b/src/php/composer.json
@@ -2,7 +2,7 @@
   "name": "grpc/grpc-dev",
   "description": "gRPC library for PHP - for Developement use only",
   "license": "Apache-2.0",
-  "version": "1.5.0",
+  "version": "1.7.0",
   "require": {
     "php": ">=5.5.0",
     "google/protobuf": "^v3.3.0"
diff --git a/src/php/ext/grpc/call_credentials.c b/src/php/ext/grpc/call_credentials.c
index f46091d709..1eee8645df 100644
--- a/src/php/ext/grpc/call_credentials.c
+++ b/src/php/ext/grpc/call_credentials.c
@@ -179,7 +179,7 @@ void plugin_get_metadata(void *ptr, grpc_auth_metadata_context context,
   grpc_metadata_array metadata;
   bool cleanup = true;
 
-  if (Z_TYPE_P(retval) != IS_ARRAY) {
+  if (retval == NULL || Z_TYPE_P(retval) != IS_ARRAY) {
     cleanup = false;
     code = GRPC_STATUS_INVALID_ARGUMENT;
   } else if (!create_metadata_array(retval, &metadata)) {
diff --git a/src/php/ext/grpc/channel.c b/src/php/ext/grpc/channel.c
index f1187e8722..dc3acc89bb 100644
--- a/src/php/ext/grpc/channel.c
+++ b/src/php/ext/grpc/channel.c
@@ -66,6 +66,8 @@ PHP_GRPC_FREE_WRAPPED_FUNC_START(wrapped_grpc_channel)
       if (!(PHP_GRPC_PERSISTENT_LIST_FIND(&EG(persistent_list), p->wrapper->key,
                                           key_len, rsrc))) {
         grpc_channel_destroy(p->wrapper->wrapped);
+        free(p->wrapper->target);
+        free(p->wrapper->args_hashstr);
       }
       gpr_mu_unlock(&global_persistent_list_mu);
     }
@@ -158,7 +160,7 @@ void create_and_add_channel_to_persistent_list(
     grpc_channel_args args,
     wrapped_grpc_channel_credentials *creds,
     char *key,
-    php_grpc_int key_len) {
+    php_grpc_int key_len TSRMLS_DC) {
   php_grpc_zend_resource new_rsrc;
   channel_persistent_le_t *le;
   // this links each persistent list entry to a destructor
@@ -187,10 +189,8 @@ void create_and_add_channel_to_persistent_list(
  * credentials.
  *
  * If the $args array contains a "force_new" key mapping to a boolean value
- * of "true", a new underlying grpc_channel will be created regardless. If
- * there are any opened channels on the same hostname, user must manually
- * call close() on those dangling channels before the end of the PHP
- * script.
+ * of "true", a new and separate underlying grpc_channel will be created
+ * and returned. This will not affect existing channels.
  *
  * @param string $target The hostname to associate with this channel
  * @param array $args_array The arguments to pass to the Channel
@@ -273,19 +273,15 @@ PHP_METHOD(Channel, __construct) {
   }
   channel->wrapper = malloc(sizeof(grpc_channel_wrapper));
   channel->wrapper->key = key;
-  channel->wrapper->target = target;
-  channel->wrapper->args_hashstr = sha1str;
+  channel->wrapper->target = strdup(target);
+  channel->wrapper->args_hashstr = strdup(sha1str);
   if (creds != NULL && creds->hashstr != NULL) {
     channel->wrapper->creds_hashstr = creds->hashstr;
   }
   gpr_mu_init(&channel->wrapper->mu);
   smart_str_free(&buf);
 
-  if (force_new) {
-    php_grpc_delete_persistent_list_entry(key, key_len TSRMLS_CC);
-  }
-
-  if (creds != NULL && creds->has_call_creds) {
+  if (force_new || (creds != NULL && creds->has_call_creds)) {
     // If the ChannelCredentials object was composed with a CallCredentials
     // object, there is no way we can tell them apart. Do NOT persist
     // them. They should be individually destroyed.
@@ -293,7 +289,7 @@ PHP_METHOD(Channel, __construct) {
   } else if (!(PHP_GRPC_PERSISTENT_LIST_FIND(&EG(persistent_list), key,
                                              key_len, rsrc))) {
     create_and_add_channel_to_persistent_list(
-        channel, target, args, creds, key, key_len);
+        channel, target, args, creds, key, key_len TSRMLS_CC);
   } else {
     // Found a previously stored channel in the persistent list
     channel_persistent_le_t *le = (channel_persistent_le_t *)rsrc->ptr;
@@ -303,7 +299,7 @@ PHP_METHOD(Channel, __construct) {
          strcmp(creds->hashstr, le->channel->creds_hashstr) != 0)) {
       // somehow hash collision
       create_and_add_channel_to_persistent_list(
-          channel, target, args, creds, key, key_len);
+          channel, target, args, creds, key, key_len TSRMLS_CC);
     } else {
       channel->wrapper = le->channel;
     }
@@ -416,12 +412,14 @@ PHP_METHOD(Channel, close) {
   gpr_mu_lock(&channel->wrapper->mu);
   if (channel->wrapper->wrapped != NULL) {
     grpc_channel_destroy(channel->wrapper->wrapped);
+    free(channel->wrapper->target);
+    free(channel->wrapper->args_hashstr);
     channel->wrapper->wrapped = NULL;
-  }
 
-  php_grpc_delete_persistent_list_entry(channel->wrapper->key,
-                                        strlen(channel->wrapper->key)
-                                        TSRMLS_CC);
+    php_grpc_delete_persistent_list_entry(channel->wrapper->key,
+                                          strlen(channel->wrapper->key)
+                                          TSRMLS_CC);
+  }
   gpr_mu_unlock(&channel->wrapper->mu);
 }
 
@@ -449,12 +447,11 @@ static void php_grpc_channel_plink_dtor(php_grpc_zend_resource *rsrc
     gpr_mu_lock(&le->channel->mu);
     if (le->channel->wrapped != NULL) {
       grpc_channel_destroy(le->channel->wrapped);
-      free(le->channel->key);
-      free(le->channel);
+      free(le->channel->target);
+      free(le->channel->args_hashstr);
     }
     gpr_mu_unlock(&le->channel->mu);
   }
-  free(le);
 }
 
 ZEND_BEGIN_ARG_INFO_EX(arginfo_construct, 0, 0, 2)
@@ -496,6 +493,7 @@ GRPC_STARTUP_FUNCTION(channel) {
   INIT_CLASS_ENTRY(ce, "Grpc\\Channel", channel_methods);
   ce.create_object = create_wrapped_grpc_channel;
   grpc_ce_channel = zend_register_internal_class(&ce TSRMLS_CC);
+  gpr_mu_init(&global_persistent_list_mu);
   le_plink = zend_register_list_destructors_ex(
       NULL, php_grpc_channel_plink_dtor, "Persistent Channel", module_number);
   PHP_GRPC_INIT_HANDLER(wrapped_grpc_channel, channel_ce_handlers);
diff --git a/src/php/ext/grpc/channel_credentials.c b/src/php/ext/grpc/channel_credentials.c
index 19e1cefb6f..86e4f46c67 100644
--- a/src/php/ext/grpc/channel_credentials.c
+++ b/src/php/ext/grpc/channel_credentials.c
@@ -135,6 +135,8 @@ PHP_METHOD(ChannelCredentials, createSsl) {
 
   pem_key_cert_pair.private_key = pem_key_cert_pair.cert_chain = NULL;
 
+  grpc_set_ssl_roots_override_callback(get_ssl_roots_override);
+
   /* "|s!s!s!" == 3 optional nullable strings */
   if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|s!s!s!",
                             &pem_root_certs, &root_certs_length,
@@ -148,7 +150,7 @@ PHP_METHOD(ChannelCredentials, createSsl) {
   }
 
   php_grpc_int hashkey_len = root_certs_length + cert_chain_length;
-  char hashkey[hashkey_len];
+  char *hashkey = emalloc(hashkey_len);
   if (root_certs_length > 0) {
     strcpy(hashkey, pem_root_certs);
   }
@@ -164,6 +166,7 @@ PHP_METHOD(ChannelCredentials, createSsl) {
       pem_key_cert_pair.private_key == NULL ? NULL : &pem_key_cert_pair, NULL);
   zval *creds_object = grpc_php_wrap_channel_credentials(creds, hashstr, false
                                                          TSRMLS_CC);
+  efree(hashkey);
   RETURN_DESTROY_ZVAL(creds_object);
 }
 
@@ -177,6 +180,8 @@ PHP_METHOD(ChannelCredentials, createComposite) {
   zval *cred1_obj;
   zval *cred2_obj;
 
+  grpc_set_ssl_roots_override_callback(get_ssl_roots_override);
+
   /* "OO" == 2 Objects */
   if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "OO", &cred1_obj,
                             grpc_ce_channel_credentials, &cred2_obj,
@@ -245,7 +250,6 @@ void grpc_init_channel_credentials(TSRMLS_D) {
   zend_class_entry ce;
   INIT_CLASS_ENTRY(ce, "Grpc\\ChannelCredentials",
                    channel_credentials_methods);
-  grpc_set_ssl_roots_override_callback(get_ssl_roots_override);
   ce.create_object = create_wrapped_grpc_channel_credentials;
   grpc_ce_channel_credentials = zend_register_internal_class(&ce TSRMLS_CC);
   PHP_GRPC_INIT_HANDLER(wrapped_grpc_channel_credentials,
diff --git a/src/php/ext/grpc/php_grpc.c b/src/php/ext/grpc/php_grpc.c
index a96daf7d9b..4ed56de993 100644
--- a/src/php/ext/grpc/php_grpc.c
+++ b/src/php/ext/grpc/php_grpc.c
@@ -34,7 +34,8 @@
 #include <ext/standard/info.h>
 #include "php_grpc.h"
 
-// ZEND_DECLARE_MODULE_GLOBALS(grpc)
+ZEND_DECLARE_MODULE_GLOBALS(grpc)
+static PHP_GINIT_FUNCTION(grpc);
 
 /* {{{ grpc_functions[]
  *
@@ -55,13 +56,17 @@ zend_module_entry grpc_module_entry = {
   grpc_functions,
   PHP_MINIT(grpc),
   PHP_MSHUTDOWN(grpc),
-  NULL,
+  PHP_RINIT(grpc),
   NULL,
   PHP_MINFO(grpc),
 #if ZEND_MODULE_API_NO >= 20010901
   PHP_GRPC_VERSION,
 #endif
-  STANDARD_MODULE_PROPERTIES};
+  PHP_MODULE_GLOBALS(grpc),
+  PHP_GINIT(grpc),
+  NULL,
+  NULL,
+  STANDARD_MODULE_PROPERTIES_EX};
 /* }}} */
 
 #ifdef COMPILE_DL_GRPC
@@ -99,7 +104,6 @@ PHP_MINIT_FUNCTION(grpc) {
      REGISTER_INI_ENTRIES();
   */
   /* Register call error constants */
-  grpc_init();
   REGISTER_LONG_CONSTANT("Grpc\\CALL_OK", GRPC_CALL_OK,
                          CONST_CS | CONST_PERSISTENT);
   REGISTER_LONG_CONSTANT("Grpc\\CALL_ERROR", GRPC_CALL_ERROR,
@@ -227,7 +231,6 @@ PHP_MINIT_FUNCTION(grpc) {
   grpc_init_channel_credentials(TSRMLS_C);
   grpc_init_call_credentials(TSRMLS_C);
   grpc_init_server_credentials(TSRMLS_C);
-  grpc_php_init_completion_queue(TSRMLS_C);
   return SUCCESS;
 }
 /* }}} */
@@ -240,9 +243,12 @@ PHP_MSHUTDOWN_FUNCTION(grpc) {
   */
   // WARNING: This function IS being called by PHP when the extension
   // is unloaded but the logs were somehow suppressed.
-  grpc_shutdown_timeval(TSRMLS_C);
-  grpc_php_shutdown_completion_queue(TSRMLS_C);
-  grpc_shutdown();
+  if (GRPC_G(initialized)) {
+    grpc_shutdown_timeval(TSRMLS_C);
+    grpc_php_shutdown_completion_queue(TSRMLS_C);
+    grpc_shutdown();
+    GRPC_G(initialized) = 0;
+  }
   return SUCCESS;
 }
 /* }}} */
@@ -259,6 +265,26 @@ PHP_MINFO_FUNCTION(grpc) {
   */
 }
 /* }}} */
+
+/* {{{ PHP_RINIT_FUNCTION
+ */
+PHP_RINIT_FUNCTION(grpc) {
+  if (!GRPC_G(initialized)) {
+    grpc_init();
+    grpc_php_init_completion_queue(TSRMLS_C);
+    GRPC_G(initialized) = 1;
+  }
+  return SUCCESS;
+}
+/* }}} */
+
+/* {{{ PHP_GINIT_FUNCTION
+ */
+static PHP_GINIT_FUNCTION(grpc) {
+  grpc_globals->initialized = 0;
+}
+/* }}} */
+
 /* The previous line is meant for vim and emacs, so it can correctly fold and
    unfold functions in source code. See the corresponding marks just before
    function definition, where the functions purpose is also documented. Please
diff --git a/src/php/ext/grpc/php_grpc.h b/src/php/ext/grpc/php_grpc.h
index 32329178dc..e30f011c39 100644
--- a/src/php/ext/grpc/php_grpc.h
+++ b/src/php/ext/grpc/php_grpc.h
@@ -49,14 +49,16 @@ PHP_MINIT_FUNCTION(grpc);
 PHP_MSHUTDOWN_FUNCTION(grpc);
 /* Displays information about the module */
 PHP_MINFO_FUNCTION(grpc);
+/* Code that runs at request start */
+PHP_RINIT_FUNCTION(grpc);
 
 /*
   Declare any global variables you may need between the BEGIN
   and END macros here:
-
+*/
 ZEND_BEGIN_MODULE_GLOBALS(grpc)
+  zend_bool initialized;
 ZEND_END_MODULE_GLOBALS(grpc)
-*/
 
 /* In every utility function you add that needs to use variables
    in php_grpc_globals, call TSRMLS_FETCH(); after declaring other
diff --git a/src/php/ext/grpc/version.h b/src/php/ext/grpc/version.h
index 744028b2ca..07d8eee7fe 100644
--- a/src/php/ext/grpc/version.h
+++ b/src/php/ext/grpc/version.h
@@ -20,6 +20,6 @@
 #ifndef VERSION_H
 #define VERSION_H
 
-#define PHP_GRPC_VERSION "1.5.0dev"
+#define PHP_GRPC_VERSION "1.7.0dev"
 
 #endif /* VERSION_H */
diff --git a/src/php/lib/Grpc/ServerStreamingCall.php b/src/php/lib/Grpc/ServerStreamingCall.php
index 269a99ab59..f8fddfea01 100644
--- a/src/php/lib/Grpc/ServerStreamingCall.php
+++ b/src/php/lib/Grpc/ServerStreamingCall.php
@@ -40,13 +40,11 @@ class ServerStreamingCall extends AbstractCall
         if (array_key_exists('flags', $options)) {
             $message_array['flags'] = $options['flags'];
         }
-        $event = $this->call->startBatch([
+        $this->call->startBatch([
             OP_SEND_INITIAL_METADATA => $metadata,
-            OP_RECV_INITIAL_METADATA => true,
             OP_SEND_MESSAGE => $message_array,
             OP_SEND_CLOSE_FROM_CLIENT => true,
         ]);
-        $this->metadata = $event->metadata;
     }
 
     /**
@@ -54,9 +52,15 @@ class ServerStreamingCall extends AbstractCall
      */
     public function responses()
     {
-        $response = $this->call->startBatch([
-            OP_RECV_MESSAGE => true,
-        ])->message;
+        $batch = [OP_RECV_MESSAGE => true];
+        if ($this->metadata === null) {
+            $batch[OP_RECV_INITIAL_METADATA] = true;
+        }
+        $read_event = $this->call->startBatch($batch);
+        if ($this->metadata === null) {
+            $this->metadata = $read_event->metadata;
+        }
+        $response = $read_event->message;
         while ($response !== null) {
             yield $this->_deserializeResponse($response);
             $response = $this->call->startBatch([
@@ -81,4 +85,16 @@ class ServerStreamingCall extends AbstractCall
 
         return $status_event->status;
     }
+
+    /**
+     * @return mixed The metadata sent by the server
+     */
+    public function getMetadata()
+    {
+        if ($this->metadata === null) {
+            $event = $this->call->startBatch([OP_RECV_INITIAL_METADATA => true]);
+            $this->metadata = $event->metadata;
+        }
+        return $this->metadata;
+    }
 }
diff --git a/src/php/lib/Grpc/UnaryCall.php b/src/php/lib/Grpc/UnaryCall.php
index dd55d02165..e8496492b8 100644
--- a/src/php/lib/Grpc/UnaryCall.php
+++ b/src/php/lib/Grpc/UnaryCall.php
@@ -40,13 +40,11 @@ class UnaryCall extends AbstractCall
         if (isset($options['flags'])) {
             $message_array['flags'] = $options['flags'];
         }
-        $event = $this->call->startBatch([
+        $this->call->startBatch([
             OP_SEND_INITIAL_METADATA => $metadata,
-            OP_RECV_INITIAL_METADATA => true,
             OP_SEND_MESSAGE => $message_array,
             OP_SEND_CLOSE_FROM_CLIENT => true,
         ]);
-        $this->metadata = $event->metadata;
     }
 
     /**
@@ -56,14 +54,32 @@ class UnaryCall extends AbstractCall
      */
     public function wait()
     {
-        $event = $this->call->startBatch([
+        $batch = [
             OP_RECV_MESSAGE => true,
             OP_RECV_STATUS_ON_CLIENT => true,
-        ]);
-
+        ];
+        if ($this->metadata === null) {
+            $batch[OP_RECV_INITIAL_METADATA] = true;
+        }
+        $event = $this->call->startBatch($batch);
+        if ($this->metadata === null) {
+            $this->metadata = $event->metadata;
+        }
         $status = $event->status;
         $this->trailing_metadata = $status->metadata;
 
         return [$this->_deserializeResponse($event->message), $status];
     }
+
+    /**
+     * @return mixed The metadata sent by the server
+     */
+    public function getMetadata()
+    {
+        if ($this->metadata === null) {
+            $event = $this->call->startBatch([OP_RECV_INITIAL_METADATA => true]);
+            $this->metadata = $event->metadata;
+        }
+        return $this->metadata;
+    }
 }
diff --git a/src/php/tests/unit_tests/ChannelTest.php b/src/php/tests/unit_tests/ChannelTest.php
index 400df0fb66..c375a16269 100644
--- a/src/php/tests/unit_tests/ChannelTest.php
+++ b/src/php/tests/unit_tests/ChannelTest.php
@@ -517,8 +517,6 @@ class ChannelTest extends PHPUnit_Framework_TestCase
         $state = $this->channel2->getConnectivityState();
         $this->assertEquals(GRPC\CHANNEL_IDLE, $state);
 
-        // any dangling old connection to the same host must be
-        // manually closed
         $this->channel1->close();
         $this->channel2->close();
     }
@@ -529,6 +527,7 @@ class ChannelTest extends PHPUnit_Framework_TestCase
         $this->channel1 = new Grpc\Channel('localhost:1', []);
         $this->channel2 = new Grpc\Channel('localhost:1',
                                            ["force_new" => true]);
+        // channel3 shares with channel1
         $this->channel3 = new Grpc\Channel('localhost:1', []);
 
         // try to connect on channel2
@@ -540,29 +539,31 @@ class ChannelTest extends PHPUnit_Framework_TestCase
         $state = $this->channel2->getConnectivityState();
         $this->assertConnecting($state);
         $state = $this->channel3->getConnectivityState();
-        $this->assertConnecting($state);
+        $this->assertEquals(GRPC\CHANNEL_IDLE, $state);
 
         $this->channel1->close();
         $this->channel2->close();
     }
 
+    /**
+     * @expectedException RuntimeException
+     */
     public function testPersistentChannelForceNewOldChannelClose()
     {
 
         $this->channel1 = new Grpc\Channel('localhost:1', []);
         $this->channel2 = new Grpc\Channel('localhost:1',
                                            ["force_new" => true]);
+        // channel3 shares with channel1
         $this->channel3 = new Grpc\Channel('localhost:1', []);
 
         $this->channel1->close();
 
         $state = $this->channel2->getConnectivityState();
         $this->assertEquals(GRPC\CHANNEL_IDLE, $state);
-        $state = $this->channel3->getConnectivityState();
-        $this->assertEquals(GRPC\CHANNEL_IDLE, $state);
 
-        $this->channel2->close();
-        $this->channel3->close();
+        // channel3 already closed
+        $state = $this->channel3->getConnectivityState();
     }
 
     public function testPersistentChannelForceNewNewChannelClose()
diff --git a/src/python/grpcio/grpc/_grpcio_metadata.py b/src/python/grpcio/grpc/_grpcio_metadata.py
index dcb46459a2..a4eb358c4e 100644
--- a/src/python/grpcio/grpc/_grpcio_metadata.py
+++ b/src/python/grpcio/grpc/_grpcio_metadata.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc/_grpcio_metadata.py.template`!!!
 
-__version__ = """1.5.0.dev0"""
+__version__ = """1.7.0.dev0"""
diff --git a/src/python/grpcio/grpc_version.py b/src/python/grpcio/grpc_version.py
index 1bbd1e149e..3194a893d7 100644
--- a/src/python/grpcio/grpc_version.py
+++ b/src/python/grpcio/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc_version.py.template`!!!
 
-VERSION='1.5.0.dev0'
+VERSION='1.7.0.dev0'
diff --git a/src/python/grpcio_health_checking/grpc_version.py b/src/python/grpcio_health_checking/grpc_version.py
index 8aa5118f39..ef68bad17a 100644
--- a/src/python/grpcio_health_checking/grpc_version.py
+++ b/src/python/grpcio_health_checking/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_health_checking/grpc_version.py.template`!!!
 
-VERSION='1.5.0.dev0'
+VERSION='1.7.0.dev0'
diff --git a/src/python/grpcio_reflection/grpc_version.py b/src/python/grpcio_reflection/grpc_version.py
index a23b9b5edb..55ab959cc5 100644
--- a/src/python/grpcio_reflection/grpc_version.py
+++ b/src/python/grpcio_reflection/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_reflection/grpc_version.py.template`!!!
 
-VERSION='1.5.0.dev0'
+VERSION='1.7.0.dev0'
diff --git a/src/python/grpcio_tests/grpc_version.py b/src/python/grpcio_tests/grpc_version.py
index fd47b426ac..9e54dc9f75 100644
--- a/src/python/grpcio_tests/grpc_version.py
+++ b/src/python/grpcio_tests/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_tests/grpc_version.py.template`!!!
 
-VERSION='1.5.0.dev0'
+VERSION='1.7.0.dev0'
diff --git a/src/ruby/lib/grpc/generic/rpc_desc.rb b/src/ruby/lib/grpc/generic/rpc_desc.rb
index 89cf8ff6a0..6fb6c412fb 100644
--- a/src/ruby/lib/grpc/generic/rpc_desc.rb
+++ b/src/ruby/lib/grpc/generic/rpc_desc.rb
@@ -99,9 +99,13 @@ module GRPC
       # event.  Send a status of deadline exceeded
       GRPC.logger.warn("late call: #{active_call}")
       send_status(active_call, DEADLINE_EXCEEDED, 'late')
-    rescue StandardError => e
+    rescue StandardError, NotImplementedError => e
       # This will usuaally be an unhandled error in the handling code.
       # Send back a UNKNOWN status to the client
+      #
+      # Note: this intentionally does not map NotImplementedError to
+      # UNIMPLEMENTED because NotImplementedError is intended for low-level
+      # OS interaction (e.g. syscalls) not supported by the current OS.
       GRPC.logger.warn("failed handler: #{active_call}; sending status:UNKNOWN")
       GRPC.logger.warn(e)
       send_status(active_call, UNKNOWN, "#{e.class}: #{e.message}")
diff --git a/src/ruby/lib/grpc/version.rb b/src/ruby/lib/grpc/version.rb
index 0aaf44947a..228c01a92c 100644
--- a/src/ruby/lib/grpc/version.rb
+++ b/src/ruby/lib/grpc/version.rb
@@ -14,5 +14,5 @@
 
 # GRPC contains the General RPC module.
 module GRPC
-  VERSION = '1.5.0.dev'
+  VERSION = '1.7.0.dev'
 end
diff --git a/src/ruby/spec/generic/rpc_desc_spec.rb b/src/ruby/spec/generic/rpc_desc_spec.rb
index be578c40d3..6852b9804f 100644
--- a/src/ruby/spec/generic/rpc_desc_spec.rb
+++ b/src/ruby/spec/generic/rpc_desc_spec.rb
@@ -52,6 +52,13 @@ describe GRPC::RpcDesc do
       this_desc.run_server_method(@call, method(:other_error))
     end
 
+    it 'sends status UNKNOWN if NotImplementedErrors are raised' do
+      expect(@call).to receive(:read_unary_request).once.and_return(Object.new)
+      expect(@call).to receive(:send_status).once.with(
+        UNKNOWN, not_implemented_error_msg, false, metadata: {})
+      this_desc.run_server_method(@call, method(:not_implemented))
+    end
+
     it 'absorbs CallError with no further action' do
       expect(@call).to receive(:read_unary_request).once.and_raise(CallError)
       blk = proc do
@@ -102,6 +109,12 @@ describe GRPC::RpcDesc do
         @client_streamer.run_server_method(@call, method(:other_error_alt))
       end
 
+      it 'sends status UNKNOWN if NotImplementedErrors are raised' do
+        expect(@call).to receive(:send_status).once.with(
+          UNKNOWN, not_implemented_error_msg, false, metadata: {})
+        @client_streamer.run_server_method(@call, method(:not_implemented_alt))
+      end
+
       it 'absorbs CallError with no further action' do
         expect(@call).to receive(:server_unary_response).once.and_raise(
           CallError)
@@ -166,6 +179,14 @@ describe GRPC::RpcDesc do
         @bidi_streamer.run_server_method(@call, method(:other_error_alt))
       end
 
+      it 'sends status UNKNOWN if NotImplementedErrors are raised' do
+        expect(@call).to receive(:run_server_bidi).and_raise(
+          not_implemented_error)
+        expect(@call).to receive(:send_status).once.with(
+          UNKNOWN, not_implemented_error_msg, false, metadata: {})
+        @bidi_streamer.run_server_method(@call, method(:not_implemented_alt))
+      end
+
       it 'closes the stream if there no errors' do
         expect(@call).to receive(:run_server_bidi)
         expect(@call).to receive(:output_metadata).and_return(fake_md)
@@ -329,8 +350,25 @@ describe GRPC::RpcDesc do
     fail(ArgumentError, 'other error')
   end
 
+  def not_implemented(_req, _call)
+    fail not_implemented_error
+  end
+
+  def not_implemented_alt(_call)
+    fail not_implemented_error
+  end
+
   def arg_error_msg(error = nil)
     error ||= ArgumentError.new('other error')
     "#{error.class}: #{error.message}"
   end
+
+  def not_implemented_error
+    NotImplementedError.new('some OS feature not implemented')
+  end
+
+  def not_implemented_error_msg(error = nil)
+    error ||= not_implemented_error
+    "#{error.class}: #{error.message}"
+  end
 end
diff --git a/src/ruby/tools/version.rb b/src/ruby/tools/version.rb
index 4c5293241d..ea0c4ae56c 100644
--- a/src/ruby/tools/version.rb
+++ b/src/ruby/tools/version.rb
@@ -14,6 +14,6 @@
 
 module GRPC
   module Tools
-    VERSION = '1.5.0.dev'
+    VERSION = '1.7.0.dev'
   end
 end