Use no thread

paddle/fluid/framework/parallel_executor.cc

@@ -109,7 +109,6 @@ struct OpHandle {
 
   virtual void Wait(platform::DeviceContext *waited_dev) {
     if (platform::is_cpu_place(waited_dev->GetPlace()) || events_.empty()) {
-      VLOG(4) << "I am here";
       for (auto &dev_ctx : dev_ctx_) {
         dev_ctx.second->Wait();
       }
@@ -255,7 +254,7 @@ struct FetchOpHandle : public OpHandle {
 
 class ParallelExecutorPrivate {
  public:
-  explicit ParallelExecutorPrivate(size_t num_threads = 12)
+  explicit ParallelExecutorPrivate(size_t num_threads = 0)
       : pool_(num_threads == 0 ? nullptr : new ThreadPool(num_threads)) {}
 
   std::vector<platform::Place> places_;
@@ -397,8 +396,6 @@ struct NCCLAllReduceOpHandle : public OpHandle {
       }
       platform::dynload::ncclGroupEnd();
       PADDLE_ENFORCE(cudaDeviceSynchronize());
-
-      VLOG(3) << "After NCCL";
     }
   }
 };