fix parallel executor async mode

paddle/fluid/framework/parallel_executor.cc

@@ -188,7 +188,7 @@ ParallelExecutor::ParallelExecutor(
     const std::string &loss_var_name, Scope *scope,
     const std::vector<Scope *> &local_scopes,
     const ExecutionStrategy &exec_strategy, const BuildStrategy &build_strategy,
-    std::vector<ir::Graph *> graphs)
+    ir::Graph *graph)
     : member_(new ParallelExecutorPrivate(places)) {
   member_->global_scope_ = scope;
   member_->use_cuda_ = exec_strategy.use_cuda_;
@@ -218,12 +218,18 @@ ParallelExecutor::ParallelExecutor(
     }
   }
 
+  std::vector<ir::Graph *> graphs;
   if (build_strategy.async_mode_) {
     PADDLE_ENFORCE(!member_->use_cuda_,
                    "gpu mode does not support async_mode_ now!");
+    graphs.push_back(graph);
+    for (int i = 1; i < places.size(); ++i) {
+      auto *tmp_graph = new ir::Graph(graph->OriginProgram());
+      async_graphs_.emplace_back(tmp_graph);
+      graphs.push_back(tmp_graph);
+    }
   }
 
-  ir::Graph *graph = graphs[0];
   std::unique_ptr<ir::Graph> temp_owned_graph(graph);
 
   // FIXME(Yancey1989): parallel graph mode get better performance

paddle/fluid/framework/parallel_executor.h

@@ -50,7 +50,7 @@ class ParallelExecutor {
                             const std::vector<Scope *> &local_scopes,
                             const ExecutionStrategy &exec_strategy,
                             const BuildStrategy &build_strategy,
-                            std::vector<ir::Graph *> graphs);
+                            ir::Graph *graph);
 
   ~ParallelExecutor();
 
@@ -76,6 +76,7 @@ class ParallelExecutor {
                                     const BuildStrategy &build_strategy) const;
 
   ParallelExecutorPrivate *member_;
+  std::vector<std::unique_ptr<ir::Graph>> async_graphs_;
 #if defined(PADDLE_WITH_CUDA) && !defined(_WIN32)
   std::unique_ptr<ncclUniqueId> local_nccl_id_;
 #endif

paddle/fluid/pybind/pybind.cc

@@ -1271,7 +1271,7 @@ All parameter, weight, gradient are variables in Paddle.
   pe.def(py::init<const std::vector<platform::Place> &,
                   const std::unordered_set<std::string> &, const std::string &,
                   Scope *, std::vector<Scope *> &, const ExecutionStrategy &,
-                  const BuildStrategy &, std::vector<ir::Graph *>>())
+                  const BuildStrategy &, ir::Graph *>())
       // NOTE: even we return a vec<Scope*>* to Python use reference policy.
       // We still cannot get local_scope from this vector, since the element
       // of vec<Scope*> will be freed by Python GC. We can only return Scope*