Merge pull request #14056 from panyx0718/fix

Fix threadpool

Author: panyx0718

paddle/fluid/framework/threadpool.cc

@@ -25,7 +25,6 @@ DEFINE_int32(dist_threadpool_size, 0,
 
 namespace paddle {
 namespace framework {
-
 std::unique_ptr<ThreadPool> ThreadPool::threadpool_(nullptr);
 std::once_flag ThreadPool::init_flag_;
 
@@ -47,8 +46,7 @@ void ThreadPool::Init() {
   }
 }
 
-ThreadPool::ThreadPool(int num_threads)
-    : total_threads_(num_threads), idle_threads_(num_threads), running_(true) {
+ThreadPool::ThreadPool(int num_threads) : running_(true) {
   threads_.resize(num_threads);
   for (auto& thread : threads_) {
     // TODO(Yancey1989): binding the thread on the specify CPU number
@@ -59,6 +57,7 @@ ThreadPool::ThreadPool(int num_threads)
 ThreadPool::~ThreadPool() {
   {
     // notify all threads to stop running
+    std::lock_guard<std::mutex> l(mutex_);
     running_ = false;
     scheduled_.notify_all();
   }
@@ -69,36 +68,24 @@ ThreadPool::~ThreadPool() {
   }
 }
 
-void ThreadPool::Wait() {
-  std::unique_lock<std::mutex> lock(mutex_);
-  completed_.wait(lock, [=] { return Done() == true; });
-}
-
 void ThreadPool::TaskLoop() {
-  while (running_) {
+  while (true) {
     std::unique_lock<std::mutex> lock(mutex_);
-    scheduled_.wait(lock, [=] { return !tasks_.empty() || !running_; });
 
-    if (!running_) {
-      break;
+    scheduled_.wait(
+        lock, [this] { return !this->tasks_.empty() || !this->running_; });
+
+    if (!running_ || tasks_.empty()) {
+      return;
     }
+
     // pop a task from the task queue
     auto task = std::move(tasks_.front());
     tasks_.pop();
-
-    --idle_threads_;
     lock.unlock();
 
     // run the task
     task();
-
-    {
-      std::unique_lock<std::mutex> lock(mutex_);
-      ++idle_threads_;
-      if (Done()) {
-        completed_.notify_all();
-      }
-    }
   }
 }
 

paddle/fluid/framework/threadpool.h

@@ -57,15 +57,6 @@ class ThreadPool {
 
   ~ThreadPool();
 
-  // Returns the number of threads created by the constructor.
-  size_t Threads() const { return total_threads_; }
-
-  // Returns the number of currently idle threads.
-  size_t IdleThreads() {
-    std::unique_lock<std::mutex> lock(mutex_);
-    return idle_threads_;
-  }
-
   // Run pushes a function to the task queue and returns a std::future
   // object.  To wait for the completion of the task, call
   // std::future::wait().
@@ -94,25 +85,13 @@ class ThreadPool {
     });
     std::future<std::unique_ptr<platform::EnforceNotMet>> f = task.get_future();
     tasks_.push(std::move(task));
-    lock.unlock();
     scheduled_.notify_one();
     return f;
   }
 
-  // Wait until all the tasks are completed.
-  void Wait();
-
  private:
   DISABLE_COPY_AND_ASSIGN(ThreadPool);
 
-  // If the task queue is empty and avaialbe is equal to the number of
-  // threads, means that all tasks are completed.  Note: this function
-  // is not thread-safe.  Returns true if all tasks are completed.
-  // Note: don't delete the data member total_threads_ and use
-  // threads_.size() instead; because you'd need to lock the mutex
-  // before accessing threads_.
-  bool Done() { return tasks_.empty() && idle_threads_ == total_threads_; }
-
   // The constructor starts threads to run TaskLoop, which retrieves
   // and runs tasks from the queue.
   void TaskLoop();
@@ -125,14 +104,11 @@ class ThreadPool {
   static std::once_flag init_flag_;
 
   std::vector<std::unique_ptr<std::thread>> threads_;
-  const size_t total_threads_;
-  size_t idle_threads_;
 
   std::queue<Task> tasks_;
   std::mutex mutex_;
   bool running_;
   std::condition_variable scheduled_;
-  std::condition_variable completed_;
 };
 
 class ThreadPoolIO : ThreadPool {

paddle/fluid/framework/threadpool_test.cc

@@ -19,10 +19,11 @@ limitations under the License. */
 
 namespace framework = paddle::framework;
 
-void do_sum(framework::ThreadPool* pool, std::atomic<int>* sum, int cnt) {
-  std::vector<std::future<void>> fs;
+void do_sum(std::vector<std::future<void>>* fs, std::mutex* mu,
+            std::atomic<int>* sum, int cnt) {
   for (int i = 0; i < cnt; ++i) {
-    fs.push_back(framework::Async([sum]() { sum->fetch_add(1); }));
+    std::lock_guard<std::mutex> l(*mu);
+    fs->push_back(framework::Async([sum]() { sum->fetch_add(1); }));
   }
 }
 
@@ -40,18 +41,21 @@ TEST(ThreadPool, ConcurrentInit) {
 }
 
 TEST(ThreadPool, ConcurrentRun) {
-  framework::ThreadPool* pool = framework::ThreadPool::GetInstance();
   std::atomic<int> sum(0);
   std::vector<std::thread> threads;
+  std::vector<std::future<void>> fs;
+  std::mutex fs_mu;
   int n = 50;
   // sum = (n * (n + 1)) / 2
   for (int i = 1; i <= n; ++i) {
-    std::thread t(do_sum, pool, &sum, i);
+    std::thread t(do_sum, &fs, &fs_mu, &sum, i);
     threads.push_back(std::move(t));
   }
   for (auto& t : threads) {
     t.join();
   }
-  pool->Wait();
+  for (auto& t : fs) {
+    t.wait();
+  }
   EXPECT_EQ(sum, ((n + 1) * n) / 2);
 }