From 8d176bbf50c7bc1a421bb857c1c935fe5353c317 Mon Sep 17 00:00:00 2001 From: Mehdi Amini Date: Tue, 15 Dec 2015 00:42:44 +0000 Subject: [PATCH] Revert "Add a C++11 ThreadPool implementation in LLVM" This reverts commit r255589. Breaks g++ From: Mehdi Amini git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255591 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/ThreadPool.h | 113 ----------------------- include/llvm/Support/thread.h | 2 - lib/Support/CMakeLists.txt | 1 - lib/Support/ThreadPool.cpp | 146 ------------------------------ unittests/Support/CMakeLists.txt | 1 - unittests/Support/ThreadPool.cpp | 91 ------------------- 6 files changed, 354 deletions(-) delete mode 100644 include/llvm/Support/ThreadPool.h delete mode 100644 lib/Support/ThreadPool.cpp delete mode 100644 unittests/Support/ThreadPool.cpp diff --git a/include/llvm/Support/ThreadPool.h b/include/llvm/Support/ThreadPool.h deleted file mode 100644 index 8a90c85865a..00000000000 --- a/include/llvm/Support/ThreadPool.h +++ /dev/null @@ -1,113 +0,0 @@ -//===-- llvm/Support/ThreadPool.h - A ThreadPool implementation -*- C++ -*-===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This file defines a crude C++11 based thread pool. -// -//===----------------------------------------------------------------------===// - -#ifndef LLVM_SUPPORT_THREAD_POOL_H -#define LLVM_SUPPORT_THREAD_POOL_H - -#include "llvm/Support/thread.h" - -#include -#include -#include -#include -#include -#include -#include - -namespace llvm { - -/// A ThreadPool for asynchronous parallel execution on a defined number of -/// threads. -/// -/// The pool keeps a vector of threads alive, waiting on a condition variable -/// for some work to become available. -class ThreadPool { -public: -#ifndef _MSC_VER - using VoidTy = void; -#else - // MSVC 2013 has a bug and can't use std::packaged_task; - // We force it to use bool(bool) instead. - using VoidTy = bool; -#endif - using TaskTy = std::function; - using PackagedTaskTy = std::packaged_task; - - /// Construct a pool with the number of core available on the system (or - /// whatever the value returned by std::thread::hardware_concurrency() is). - ThreadPool(); - - /// Construct a pool of \p ThreadCount threads - ThreadPool(unsigned ThreadCount); - - /// Blocking destructor: the pool will wait for all the threads to complete. - ~ThreadPool(); - - /// Asynchronous submission of a task to the pool. The returned future can be - /// used to wait for the task to finish and is *non-blocking* on destruction. - template - inline std::shared_future async(Function &&F, Args &&... ArgList) { - auto Task = - std::bind(std::forward(F), std::forward(ArgList...)); -#ifndef _MSC_VER - return asyncImpl(std::move(Task)); -#else - return asyncImpl([Task] (VoidTy) -> VoidTy { Task(); return VoidTy(); }); -#endif - } - - /// Asynchronous submission of a task to the pool. The returned future can be - /// used to wait for the task to finish and is *non-blocking* on destruction. - template - inline std::shared_future async(Function &&F) { -#ifndef _MSC_VER - return asyncImpl(std::forward(F)); -#else - return asyncImpl([F] (VoidTy) -> VoidTy { F(); return VoidTy(); }); -#endif - } - - /// Blocking wait for all the threads to complete and the queue to be empty. - /// It is an error to try to add new tasks while blocking on this call. - void wait(); - -private: - /// Asynchronous submission of a task to the pool. The returned future can be - /// used to wait for the task to finish and is *non-blocking* on destruction. - std::shared_future asyncImpl(TaskTy F); - - /// Threads in flight - std::vector Threads; - - /// Tasks waiting for execution in the pool. - std::queue Tasks; - - /// Locking and signaling for accessing the Tasks queue. - std::mutex QueueLock; - std::condition_variable QueueCondition; - - /// Locking and signaling for job completion - std::mutex CompletionLock; - std::condition_variable CompletionCondition; - - /// Keep track of the number of thread actually busy - std::atomic ActiveThreads; - -#if LLVM_ENABLE_THREADS // avoids warning for unused variable - /// Signal for the destruction of the pool, asking thread to exit. - bool EnableFlag; -#endif -}; -} - -#endif // LLVM_SUPPORT_THREAD_POOL_H diff --git a/include/llvm/Support/thread.h b/include/llvm/Support/thread.h index 2d130418a57..2d1f1b3a3ec 100644 --- a/include/llvm/Support/thread.h +++ b/include/llvm/Support/thread.h @@ -43,8 +43,6 @@ typedef std::thread thread; #else // !LLVM_ENABLE_THREADS -#include - namespace llvm { struct thread { diff --git a/lib/Support/CMakeLists.txt b/lib/Support/CMakeLists.txt index 75b3e89f916..784e00e15b9 100644 --- a/lib/Support/CMakeLists.txt +++ b/lib/Support/CMakeLists.txt @@ -89,7 +89,6 @@ add_llvm_library(LLVMSupport StringRef.cpp SystemUtils.cpp TargetParser.cpp - ThreadPool.cpp Timer.cpp ToolOutputFile.cpp Triple.cpp diff --git a/lib/Support/ThreadPool.cpp b/lib/Support/ThreadPool.cpp deleted file mode 100644 index bc004dfb8a8..00000000000 --- a/lib/Support/ThreadPool.cpp +++ /dev/null @@ -1,146 +0,0 @@ -//==-- llvm/Support/ThreadPool.cpp - A ThreadPool implementation -*- C++ -*-==// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This file implements a crude C++11 based thread pool. -// -//===----------------------------------------------------------------------===// - -#include "llvm/Support/ThreadPool.h" - -#include "llvm/Config/llvm-config.h" -#include "llvm/Support/raw_ostream.h" - -using namespace llvm; - -#if LLVM_ENABLE_THREADS - -// Default to std::thread::hardware_concurrency -ThreadPool::ThreadPool() : ThreadPool(std::thread::hardware_concurrency()) {} - -ThreadPool::ThreadPool(unsigned ThreadCount) - : ActiveThreads(0), EnableFlag(true) { - // Create ThreadCount threads that will loop forever, wait on QueueCondition - // for tasks to be queued or the Pool to be destroyed. - Threads.reserve(ThreadCount); - for (unsigned ThreadID = 0; ThreadID < ThreadCount; ++ThreadID) { - Threads.emplace_back([&] { - while (true) { - PackagedTaskTy Task; - { - std::unique_lock LockGuard(QueueLock); - // Wait for tasks to be pushed in the queue - QueueCondition.wait(LockGuard, - [&] { return !EnableFlag || !Tasks.empty(); }); - // Exit condition - if (!EnableFlag && Tasks.empty()) - return; - // Yeah, we have a task, grab it and release the lock on the queue - - // We first need to signal that we are active before popping the queue - // in order for wait() to properly detect that even if the queue is - // empty, there is still a task in flight. - { - ++ActiveThreads; - std::unique_lock LockGuard(CompletionLock); - } - Task = std::move(Tasks.front()); - Tasks.pop(); - } - // Run the task we just grabbed -#ifndef _MSC_VER - Task(); -#else - Task(/* unused */ false); -#endif - - { - // Adjust `ActiveThreads`, in case someone waits on ThreadPool::wait() - std::unique_lock LockGuard(CompletionLock); - --ActiveThreads; - } - - // Notify task completion, in case someone waits on ThreadPool::wait() - CompletionCondition.notify_all(); - } - }); - } -} - -void ThreadPool::wait() { - // Wait for all threads to complete and the queue to be empty - std::unique_lock LockGuard(CompletionLock); - CompletionCondition.wait(LockGuard, - [&] { return Tasks.empty() && !ActiveThreads; }); -} - -std::shared_future ThreadPool::asyncImpl(TaskTy Task) { - /// Wrap the Task in a packaged_task to return a future object. - PackagedTaskTy PackagedTask(std::move(Task)); - auto Future = PackagedTask.get_future(); - { - // Lock the queue and push the new task - std::unique_lock LockGuard(QueueLock); - - // Don't allow enqueueing after disabling the pool - assert(EnableFlag && "Queuing a thread during ThreadPool destruction"); - - Tasks.push(std::move(PackagedTask)); - } - QueueCondition.notify_one(); - return Future.share(); -} - -// The destructor joins all threads, waiting for completion. -ThreadPool::~ThreadPool() { - { - std::unique_lock LockGuard(QueueLock); - EnableFlag = false; - } - QueueCondition.notify_all(); - for (auto &Worker : Threads) - Worker.join(); -} - -#else // LLVM_ENABLE_THREADS Disabled - -ThreadPool::ThreadPool() : ThreadPool(0) {} - -// No threads are launched, issue a warning if ThreadCount is not 0 -ThreadPool::ThreadPool(unsigned ThreadCount) - : ActiveThreads(0) { - if (ThreadCount) { - errs() << "Warning: request a ThreadPool with " << ThreadCount - << " threads, but LLVM_ENABLE_THREADS has been turned off\n"; - } -} - -void ThreadPool::wait() { - // Sequential implementation running the tasks - while (!Tasks.empty()) { - auto Task = std::move(Tasks.front()); - Tasks.pop(); - Task(); - } -} - -std::shared_future ThreadPool::asyncImpl(TaskTy Task) { - // Get a Future with launch::deferred execution using std::async - auto Future = std::async(std::launch::deferred, std::move(Task)).share(); - // Wrap the future so that both ThreadPool::wait() can operate and the - // returned future can be sync'ed on. - PackagedTaskTy PackagedTask([Future]() { Future.get(); }); - Tasks.push(std::move(PackagedTask)); - return Future; -} - -ThreadPool::~ThreadPool() { - wait(); -} - -#endif diff --git a/unittests/Support/CMakeLists.txt b/unittests/Support/CMakeLists.txt index 9bd685759ed..fd8324c836d 100644 --- a/unittests/Support/CMakeLists.txt +++ b/unittests/Support/CMakeLists.txt @@ -41,7 +41,6 @@ add_llvm_unittest(SupportTests SwapByteOrderTest.cpp TargetRegistry.cpp ThreadLocalTest.cpp - ThreadPool.cpp TimeValueTest.cpp TrailingObjectsTest.cpp UnicodeTest.cpp diff --git a/unittests/Support/ThreadPool.cpp b/unittests/Support/ThreadPool.cpp deleted file mode 100644 index d36341e425d..00000000000 --- a/unittests/Support/ThreadPool.cpp +++ /dev/null @@ -1,91 +0,0 @@ -//========- unittests/Support/ThreadPools.cpp - ThreadPools.h tests --========// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// - -#include "llvm/Support/ThreadPool.h" - -#include "llvm/ADT/STLExtras.h" - -#include "gtest/gtest.h" - -using namespace llvm; -using namespace std::chrono; - -/// Try best to make this thread not progress faster than the main thread -static void yield() { -#ifdef LLVM_ENABLE_THREADS - std::this_thread::yield(); -#endif - std::this_thread::sleep_for(milliseconds(200)); -#ifdef LLVM_ENABLE_THREADS - std::this_thread::yield(); -#endif -} - -TEST(ThreadPoolTest, AsyncBarrier) { - // test that async & barrier work together properly. - - std::atomic_int checked_in{0}; - - ThreadPool Pool; - for (size_t i = 0; i < 5; ++i) { - Pool.async([&checked_in, i] { - yield(); - ++checked_in; - }); - } - ASSERT_EQ(0, checked_in); - Pool.wait(); - ASSERT_EQ(5, checked_in); -} - -TEST(ThreadPoolTest, Async) { - ThreadPool Pool; - std::atomic_int i{0}; - // sleep here just to ensure that the not-equal is correct. - Pool.async([&i] { - yield(); - ++i; - }); - Pool.async([&i] { ++i; }); - ASSERT_NE(2, i.load()); - Pool.wait(); - ASSERT_EQ(2, i.load()); -} - -TEST(ThreadPoolTest, GetFuture) { - ThreadPool Pool; - std::atomic_int i{0}; - // sleep here just to ensure that the not-equal is correct. - Pool.async([&i] { - yield(); - ++i; - }); - // Force the future using get() - Pool.async([&i] { ++i; }).get(); - ASSERT_NE(2, i.load()); - Pool.wait(); - ASSERT_EQ(2, i.load()); -} - -TEST(ThreadPoolTest, PoolDestruction) { - // Test that we are waiting on destruction - std::atomic_int checked_in{0}; - - { - ThreadPool Pool; - for (size_t i = 0; i < 5; ++i) { - Pool.async([&checked_in, i] { - yield(); - ++checked_in; - }); - } - ASSERT_EQ(0, checked_in); - } - ASSERT_EQ(5, checked_in); -}