Merge pull request #20376 from chrisse74/master

c++ check if workerthread could be spawned

src/cpp/thread_manager/thread_manager.cc

@@ -34,8 +34,12 @@ ThreadManager::WorkerThread::WorkerThread(ThreadManager* thd_mgr)
   thd_ = grpc_core::Thread(
       "grpcpp_sync_server",
       [](void* th) { static_cast<ThreadManager::WorkerThread*>(th)->Run(); },
-      this);
-  thd_.Start();
+      this, &created_);
+  if (!created_) {
+    gpr_log(GPR_ERROR, "Could not create grpc_sync_server worker-thread");
+  } else {
+    thd_.Start();
+  }
 }
 
 void ThreadManager::WorkerThread::Run() {
@@ -177,7 +181,12 @@ void ThreadManager::MainWorkLoop() {
             }
             // Drop lock before spawning thread to avoid contention
             lock.Unlock();
-            new WorkerThread(this);
+            WorkerThread* w = new WorkerThread(this);
+            if (!w->created()) {
+              num_pollers_--;
+              num_threads_--;
+              resource_exhausted = true;
+            }
           } else if (num_pollers_ > 0) {
             // There is still at least some thread polling, so we can go on
             // even though we are below the number of pollers that we would

src/cpp/thread_manager/thread_manager.h

@@ -124,6 +124,8 @@ class ThreadManager {
     WorkerThread(ThreadManager* thd_mgr);
     ~WorkerThread();
 
+    bool created() const { return created_; }
+
    private:
     // Calls thd_mgr_->MainWorkLoop() and once that completes, calls
     // thd_mgr_>MarkAsCompleted(this) to mark the thread as completed
@@ -131,6 +133,7 @@ class ThreadManager {
 
     ThreadManager* const thd_mgr_;
     grpc_core::Thread thd_;
+    bool created_;
   };
 
   // The main function in ThreadManager