add ckpt to sync loop

paddle/fluid/operators/listen_and_serv_op.cc

@@ -101,6 +101,7 @@ void ListenAndServOp::RunSyncLoop(framework::Executor *executor,
                                   framework::Scope *recv_scope,
                                   framework::BlockDesc *prefetch_block) const {
   auto fan_in = Attr<int>("Fanin");
+  auto checkpoint = Attr<std::string>("Checkpoint");
 
   size_t num_blocks = program->Size();
   PADDLE_ENFORCE_GE(num_blocks, 2,
@@ -188,6 +189,18 @@ void ListenAndServOp::RunSyncLoop(framework::Executor *executor,
     for (auto &var : sparse_vars) {
       var->GetMutable<framework::SelectedRows>()->mutable_rows()->clear();
     }
+
+    /******************** CHECK POINT ***********************/
+    std::vector<std::string> all_vars = recv_scope.LocalVarNames();
+
+    std::vector<std::string>::iterator it;
+    for (it = all_vars.begin(); it != all_vars.end(); it++) {
+      VLOG(2) << "Checkpoint Var: " << *it;
+      break;
+    }
+
+    /******************** CHECK POINT ***********************/
+
     rpc_service_->SetCond(1);
     // FIXME(typhoonzero): use another condition to sync wait clients get.
     rpc_service_->WaitClientGet(fan_in);