Make ReaderBase thread safe and remove ThreadedReader

paddle/fluid/framework/reader.cc

@@ -18,11 +18,13 @@ namespace paddle {
 namespace framework {
 
 void ReaderBase::ReadNext(std::vector<LoDTensor> *out) {
+  std::lock_guard<std::mutex> lock(mu_);
   PADDLE_ENFORCE_EQ(status_, ReaderStatus::kRunning);
   ReadNextImpl(out);
 }
 
 void ReaderBase::Shutdown() {
+  std::lock_guard<std::mutex> lock(mu_);
   if (status_ != ReaderStatus::kStopped) {
     ShutdownImpl();
     status_ = ReaderStatus::kStopped;
@@ -30,6 +32,7 @@ void ReaderBase::Shutdown() {
 }
 
 void ReaderBase::Start() {
+  std::lock_guard<std::mutex> lock(mu_);
   if (status_ != ReaderStatus::kRunning) {
     StartImpl();
     status_ = ReaderStatus::kRunning;

paddle/fluid/framework/reader.h

@@ -44,6 +44,8 @@ class ReaderBase {
   virtual void StartImpl() = 0;
 
   ReaderStatus status_{kRunning};
+
+  mutable std::mutex mu_;
 };
 
 class DecoratedReader : public ReaderBase {

paddle/fluid/operators/reader/CMakeLists.txt

@@ -22,7 +22,6 @@ reader_library(create_batch_reader_op SRCS create_batch_reader_op.cc)
 reader_library(create_recordio_file_reader_op SRCS create_recordio_file_reader_op.cc)
 reader_library(create_double_buffer_reader_op SRCS create_double_buffer_reader_op.cc)
 reader_library(create_multi_pass_reader_op SRCS create_multi_pass_reader_op.cc)
-reader_library(create_threaded_reader_op SRCS create_threaded_reader_op.cc)
 reader_library(create_custom_reader_op SRCS create_custom_reader_op.cc)
 reader_library(create_py_reader_op SRCS create_py_reader_op.cc)
 

paddle/fluid/operators/reader/create_threaded_reader_op.cc

@@ -1,84 +0,0 @@
-//   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "paddle/fluid/operators/detail/safe_ref.h"
-#include "paddle/fluid/operators/reader/reader_op_registry.h"
-
-namespace paddle {
-namespace operators {
-namespace reader {
-
-class ThreadedReader : public framework::DecoratedReader {
- public:
-  explicit ThreadedReader(const std::shared_ptr<ReaderBase>& reader)
-      : DecoratedReader(reader) {}
-
-  void ReadNextImpl(std::vector<framework::LoDTensor>* out) override {
-    std::lock_guard<std::mutex> lock(mutex_);
-    reader_->ReadNext(out);
-  }
-
- private:
-  void ShutdownImpl() override {
-    std::lock_guard<std::mutex> lock(mutex_);
-    reader_->Shutdown();
-  }
-
-  void StartImpl() override {
-    std::lock_guard<std::mutex> lock(mutex_);
-    reader_->Start();
-  }
-
-  std::mutex mutex_;
-};
-
-class CreateThreadedReaderOp : public framework::OperatorBase {
- public:
-  using framework::OperatorBase::OperatorBase;
-
- private:
-  void RunImpl(const framework::Scope& scope,
-               const platform::Place& dev_place) const override {
-    auto* out = detail::Ref(scope.FindVar(Output("Out")))
-                    .GetMutable<framework::ReaderHolder>();
-    if (out->Get() != nullptr) {
-      return;
-    }
-    const auto& underlying_reader = scope.FindVar(Input("UnderlyingReader"))
-                                        ->Get<framework::ReaderHolder>();
-    out->Reset(new ThreadedReader(underlying_reader.Get()));
-  }
-};
-
-class CreateThreadedReaderOpMaker : public DecoratedReaderMakerBase {
- protected:
-  void Apply() override {
-    AddComment(R"DOC(
-      CreateThreadedReader Operator
-
-      This operator creates a threaded reader. A threaded reader's
-      'ReadNext()' can be invoked by several threads at the same
-      time.
-    )DOC");
-  }
-};
-
-}  // namespace reader
-}  // namespace operators
-}  // namespace paddle
-
-namespace reader = paddle::operators::reader;
-REGISTER_DECORATED_READER_OPERATOR(create_threaded_reader,
-                                   reader::CreateThreadedReaderOp,
-                                   reader::CreateThreadedReaderOpMaker);

python/paddle/fluid/layers/io.py

@@ -529,9 +529,6 @@ def open_files(filenames,
         main_prog_reader = multi_pass(
             reader=main_prog_reader, pass_num=pass_num)
 
-    if for_parallel:
-        main_prog_reader = parallel(reader=main_prog_reader)
-
     return monkey_patch_reader_methods(main_prog_reader)
 
 
@@ -647,11 +644,6 @@ def multi_pass(reader, pass_num):
         'create_multi_pass_reader', reader, {'pass_num': int(pass_num)})
 
 
-def parallel(reader):
-    return __create_shared_decorated_reader__('create_threaded_reader', reader,
-                                              {})
-
-
 def read_file(reader):
     """
     Execute the given reader and get data via it.