remove some seems unused codes.

Author: panyx0718

paddle/fluid/operators/detail/request_handler.h

@@ -80,7 +80,6 @@ class RequestHandler {
   }
   framework::ProgramDesc* program() { return program_; }
   framework::Executor* executor() { return executor_; }
-  std::vector<framework::Variable*>& sparse_vars() { return sparse_vars_; }
 
   // This function processes user's rpc request.
   // The implemention is in request_handler_impl.
@@ -113,13 +112,7 @@ class RequestHandler {
   std::unordered_map<std::string,
                      std::shared_ptr<framework::ExecutorPrepareContext>>*
       grad_to_prepared_ctx_;
-
-  // Record received sparse variables, so that
-  // we could reset those after execute optimize program
-  std::vector<framework::Variable*> sparse_vars_;
   RPCServer* rpc_server_;
-
-  std::mutex sparse_var_mutex_;
 };
 
 }  // namespace detail

paddle/fluid/operators/detail/request_handler_impl.cc

@@ -63,11 +63,6 @@ bool RequestSendHandler::Handle(const std::string& varname,
       PADDLE_THROW("sync: Can not find server side var");
       return false;
     }
-
-    if (invar->IsType<framework::SelectedRows>()) {
-      std::unique_lock<std::mutex> lock(sparse_var_mutex_);
-      sparse_vars_.push_back(invar);
-    }
   }
 
   return true;

paddle/fluid/operators/listen_and_serv_op.cc

@@ -108,9 +108,6 @@ void ListenAndServOp::RunSyncLoop(framework::Executor *executor,
       std::shared_ptr<framework::ExecutorPrepareContext>(nullptr));
 
   rpc_service_->ResetBarrierCounter();
-  // Record received sparse variables, so that
-  // we could reset those after execute optimize program
-  std::vector<framework::Variable *> sparse_vars;
   while (true) {
     // Get from multiple trainers, we don't care about the order in which
     // the gradients arrives, just add suffix 0~n and merge the gradient.
@@ -146,15 +143,6 @@ void ListenAndServOp::RunSyncLoop(framework::Executor *executor,
                           recv_scope);
     VLOG(2) << "run all blocks spent " << detail::GetTimestamp() - ts << "(ms)";
 
-    // Reset the received sparse variables, the sum operator would not
-    // sum the input sparse variables which rows is empty at the next
-    // mini-batch.
-    // TODO(Yancey1989): move the reset action into an operator, we couldn't
-    // have any hide logic in the operator.
-    for (framework::Variable *var : sparse_vars) {
-      var->GetMutable<framework::SelectedRows>()->mutable_rows()->clear();
-    }
-
     rpc_service_->SetCond(detail::kRequestGet);
     rpc_service_->WaitBarrier(detail::kRequestGet);
     rpc_service_->ResetBarrierCounter();