Cleanup: Get rid of unused copy of simple threadpool implementation. The...

Cleanup: Get rid of unused copy of simple threadpool implementation. The implementation is identical to the simple threadpool in Eigen (can be selected by not defining EIGEN_USE_NONBLOCKING_THREAD_POOL), which also has had all the same tracing calls added via the hooks in EigenEnvironment.
Change: 124006070

tensorflow/core/lib/core/threadpool.cc

@@ -15,15 +15,8 @@ limitations under the License.
 
 #include "tensorflow/core/lib/core/threadpool.h"
 
-#ifdef TENSORFLOW_USE_EIGEN_THREADPOOL
 #define EIGEN_USE_THREADS
 #include "third_party/eigen3/unsupported/Eigen/CXX11/Tensor"
-#else
-#include <deque>
-#include <thread>
-#include <vector>
-#endif
-
 #include "tensorflow/core/platform/denormal.h"
 #include "tensorflow/core/platform/logging.h"
 #include "tensorflow/core/platform/mutex.h"
@@ -33,8 +26,6 @@ limitations under the License.
 namespace tensorflow {
 namespace thread {
 
-#ifdef TENSORFLOW_USE_EIGEN_THREADPOOL
-
 struct EigenEnvironment {
   typedef Thread EnvThread;
   struct Task {
@@ -105,125 +96,6 @@ struct ThreadPool::Impl : Eigen::ThreadPoolTempl<EigenEnvironment> {
   const int num_threads_;
 };
 
-#else
-
-struct ThreadPool::Impl {
-  Impl(Env* env, const ThreadOptions& thread_options, const string& name,
-       int num_threads);
-  ~Impl();
-  void Schedule(std::function<void()> fn);
-  void ParallelFor(int64 total, int64 cost_per_unit,
-                   std::function<void(int64, int64)> fn) {
-    CHECK(0);  // should not be used with the old thread pool
-  }
-
-  int NumThreads() const { return threads_.size(); };
-
- private:
-  struct Waiter {
-    condition_variable cv;
-    bool ready;
-  };
-
-  struct Task {
-    std::function<void()> fn;
-    uint64 id;
-  };
-
-  void WorkerLoop();
-
-  const string name_;
-  mutex mu_;
-  std::vector<Thread*> threads_;  // All threads
-  std::vector<Waiter*> waiters_;  // Stack of waiting threads.
-  std::deque<Task> pending_;      // Queue of pending work
-};
-
-ThreadPool::Impl::Impl(Env* env, const ThreadOptions& thread_options,
-                       const string& name, int num_threads)
-    : name_(name) {
-  for (int i = 0; i < num_threads; i++) {
-    threads_.push_back(
-        env->StartThread(thread_options, name, [this]() { WorkerLoop(); }));
-  }
-}
-
-ThreadPool::Impl::~Impl() {
-  {
-    // Wait for all work to get done.
-    mutex_lock l(mu_);
-
-    // Inform every thread to exit.
-    for (size_t i = 0; i < threads_.size(); ++i) {
-      pending_.push_back({nullptr, 0});
-    }
-
-    // Wakeup all waiters.
-    for (auto w : waiters_) {
-      w->ready = true;
-      w->cv.notify_one();
-    }
-  }
-
-  // Wait for threads to finish.
-  for (auto t : threads_) {
-    delete t;
-  }
-}
-
-void ThreadPool::Impl::Schedule(std::function<void()> fn) {
-  uint64 id = 0;
-  if (port::Tracing::IsActive()) {
-    id = port::Tracing::UniqueId();
-    port::Tracing::RecordEvent(port::Tracing::EventCategory::kScheduleClosure,
-                               id);
-  }
-
-  mutex_lock l(mu_);
-  pending_.push_back({fn, id});
-  if (!waiters_.empty()) {
-    Waiter* w = waiters_.back();
-    waiters_.pop_back();
-    w->ready = true;
-    w->cv.notify_one();
-  }
-}
-
-void ThreadPool::Impl::WorkerLoop() {
-  // Set the processor flag to flush denormals to zero
-  port::ScopedFlushDenormal flush;
-
-  port::Tracing::RegisterCurrentThread(name_.c_str());
-  mutex_lock l(mu_);
-  Waiter w;
-  while (true) {
-    while (pending_.empty()) {
-      // Wait for work to be assigned to me
-      w.ready = false;
-      waiters_.push_back(&w);
-      while (!w.ready) {
-        w.cv.wait(l);
-      }
-    }
-    // Pick up pending work
-    Task t = pending_.front();
-    pending_.pop_front();
-    if (t.fn == nullptr) {
-      break;
-    }
-    mu_.unlock();
-    if (t.id != 0) {
-      port::Tracing::ScopedActivity region(
-          port::Tracing::EventCategory::kRunClosure, t.id);
-      t.fn();
-    } else {
-      t.fn();
-    }
-    mu_.lock();
-  }
-}
-#endif
-
 ThreadPool::ThreadPool(Env* env, const string& name, int num_threads)
     : ThreadPool(env, ThreadOptions(), name, num_threads) {}
 

tensorflow/tensorflow.bzl

@@ -100,8 +100,7 @@ def if_android(a):
   })
 
 def tf_copts():
-  return (["-fno-exceptions", "-DEIGEN_AVOID_STL_ARRAY",
-           "-DTENSORFLOW_USE_EIGEN_THREADPOOL"] +
+  return (["-fno-exceptions", "-DEIGEN_AVOID_STL_ARRAY"] +
           if_cuda(["-DGOOGLE_CUDA=1"]) +
           if_android_arm(["-mfpu=neon"]) +
           select({"//tensorflow:android": [