support graceful shutdown for ps components

mindspore/ccsrc/frontend/parallel/ps/parameter_server.h

@@ -394,7 +394,7 @@ template <typename T>
 void ParameterServer<T>::UpdateWeights() {
   while (true) {
     std::unique_lock<std::mutex> lock(mutex_);
-    apply_grads_cv_.wait(lock, [this] { return this->ReadyForUpdateWeights() || running_; });
+    apply_grads_cv_.wait(lock, [this] { return this->ReadyForUpdateWeights() || !running_; });
     if (!running_) {
       break;
     }

mindspore/ccsrc/frontend/parallel/ps/worker.h

@@ -81,12 +81,12 @@ void Worker<T>::Run() {
     MS_LOG(INFO) << "'Worker is already running.";
     return;
   }
+  ::ps::Start(0);
   if (!::ps::IsWorker()) {
     MS_LOG(EXCEPTION) << "The role is not worker.";
   }
   kv_worker_ = std::make_shared<WorkerProxy<T>>(0, 0, 1);
   running_ = true;
-  ::ps::Start(0);
 }
 
 template <typename T>