Refine Shutdown Impl

paddle/fluid/operators/reader/create_double_buffer_reader_op.cc

@@ -52,12 +52,10 @@ class DoubleBufferReader : public framework::DecoratedReader {
 
   void ReadNextImpl(std::vector<framework::LoDTensor>* out) override;
 
-  ~DoubleBufferReader() { EndPrefetcher(); }
-
  private:
   void ShutdownImpl() override {
-    EndPrefetcher();
     reader_->Shutdown();
+    EndPrefetcher();
   }
 
   void StartImpl() override {

paddle/fluid/operators/reader/create_shuffle_reader_op.cc

@@ -48,9 +48,9 @@ class ShuffleReader : public framework::DecoratedReader {
 
  private:
   void ShutdownImpl() override {
+    reader_->Shutdown();
     buffer_.clear();
     iteration_pos_ = 0;
-    reader_->Shutdown();
   }
 
   void StartImpl() override {

paddle/fluid/operators/reader/open_files_op.cc

@@ -36,8 +36,6 @@ class MultiFileReader : public framework::ReaderBase {
 
   void ReadNextImpl(std::vector<framework::LoDTensor>* out) override;
 
-  ~MultiFileReader() { EndScheduler(); }
-
  private:
   void ShutdownImpl() override { EndScheduler(); }