enhance cache runtime_context for different scope

test=develop

paddle/fluid/framework/operator.cc

@@ -20,6 +20,7 @@ limitations under the License. */
 #include <string>
 #include <vector>
 #include "paddle/fluid/framework/data_transform.h"
+#include "paddle/fluid/framework/details/op_handle_base.h"
 #include "paddle/fluid/framework/executor.h"
 #include "paddle/fluid/framework/lod_tensor.h"
 #include "paddle/fluid/framework/op_proto_maker.h"
@@ -917,13 +918,18 @@ std::vector<KernelConfig>* OperatorWithKernel::GetKernelConfig(
 
 void OperatorWithKernel::RunImpl(const Scope& scope,
                                  const platform::Place& place) const {
-  if (!runtime_ctx_) {
+  const Scope* cur_scope = &scope;
+  if (!runtime_ctx_ || pre_scope_ != cur_scope ||
+      scope.FindVar(details::kLocalExecScopeName)) {
     // RuntimeContext is used to relate input/output names of Operator with
     // the corresponding variables in Scope.
-    // Since the input/output names of Operator do not change in the execution,
-    // RuntimeContext could be created only at the first iteration of
-    // the execution to save the elapsed time.
-    runtime_ctx_ = new RuntimeContext(Inputs(), Outputs(), scope);
+    // In a same Scope, since the input/output names of Operator do not change
+    // in the execution, RuntimeContext could be created only at the first
+    // iteration of the execution to save the elapsed time.
+    // Note that the Scope should not be the local scope, since local scope
+    // would be cleaned regularly.
+    runtime_ctx_.reset(new RuntimeContext(Inputs(), Outputs(), scope));
+    pre_scope_ = cur_scope;
   }
   platform::DeviceContextPool& pool = platform::DeviceContextPool::Instance();
   auto* dev_ctx = pool.Get(place);
@@ -963,8 +969,8 @@ void OperatorWithKernel::RunImpl(const Scope& scope,
 
   // do data transformScope &transfer_scope;
   std::vector<std::string> transfered_inplace_vars;
-  auto* transfer_scope = PrepareData(scope, expected_kernel_key,
-                                     &transfered_inplace_vars, runtime_ctx_);
+  auto* transfer_scope = PrepareData(
+      scope, expected_kernel_key, &transfered_inplace_vars, runtime_ctx_.get());
 
   // exec scope is the scope that kernel actually executed on.
   const Scope& exec_scope =

paddle/fluid/framework/operator.h

@@ -543,7 +543,8 @@ class OperatorWithKernel : public OperatorBase {
 
  protected:
   mutable OpKernelConfigsMap kernel_configs_map_;
-  mutable RuntimeContext* runtime_ctx_ = nullptr;
+  mutable std::unique_ptr<RuntimeContext> runtime_ctx_;
+  mutable const Scope* pre_scope_ = nullptr;
 };
 
 extern bool OpSupportGPU(const std::string& op_type);