337 lines
10 KiB
C++
337 lines
10 KiB
C++
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/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "thread_pool.h"
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#include <sys/mman.h>
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#include <sys/resource.h>
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#include <sys/time.h>
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#include <pthread.h>
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#include <android-base/logging.h>
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#include <android-base/stringprintf.h>
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#include "base/bit_utils.h"
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#include "base/casts.h"
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#include "base/stl_util.h"
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#include "base/time_utils.h"
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#include "base/utils.h"
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#include "runtime.h"
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#include "thread-current-inl.h"
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namespace art {
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using android::base::StringPrintf;
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static constexpr bool kMeasureWaitTime = false;
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#if defined(__BIONIC__)
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static constexpr bool kUseCustomThreadPoolStack = false;
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#else
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static constexpr bool kUseCustomThreadPoolStack = true;
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#endif
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ThreadPoolWorker::ThreadPoolWorker(ThreadPool* thread_pool, const std::string& name,
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size_t stack_size)
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: thread_pool_(thread_pool),
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name_(name) {
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std::string error_msg;
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// On Bionic, we know pthreads will give us a big-enough stack with
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// a guard page, so don't do anything special on Bionic libc.
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if (kUseCustomThreadPoolStack) {
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// Add an inaccessible page to catch stack overflow.
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stack_size += kPageSize;
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stack_ = MemMap::MapAnonymous(name.c_str(),
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stack_size,
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PROT_READ | PROT_WRITE,
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/*low_4gb=*/ false,
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&error_msg);
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CHECK(stack_.IsValid()) << error_msg;
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CHECK_ALIGNED(stack_.Begin(), kPageSize);
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CheckedCall(mprotect,
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"mprotect bottom page of thread pool worker stack",
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stack_.Begin(),
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kPageSize,
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PROT_NONE);
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}
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const char* reason = "new thread pool worker thread";
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pthread_attr_t attr;
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CHECK_PTHREAD_CALL(pthread_attr_init, (&attr), reason);
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if (kUseCustomThreadPoolStack) {
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CHECK_PTHREAD_CALL(pthread_attr_setstack, (&attr, stack_.Begin(), stack_.Size()), reason);
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} else {
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CHECK_PTHREAD_CALL(pthread_attr_setstacksize, (&attr, stack_size), reason);
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}
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CHECK_PTHREAD_CALL(pthread_create, (&pthread_, &attr, &Callback, this), reason);
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CHECK_PTHREAD_CALL(pthread_attr_destroy, (&attr), reason);
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}
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ThreadPoolWorker::~ThreadPoolWorker() {
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CHECK_PTHREAD_CALL(pthread_join, (pthread_, nullptr), "thread pool worker shutdown");
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}
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void ThreadPoolWorker::SetPthreadPriority(int priority) {
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CHECK_GE(priority, PRIO_MIN);
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CHECK_LE(priority, PRIO_MAX);
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#if defined(ART_TARGET_ANDROID)
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int result = setpriority(PRIO_PROCESS, pthread_gettid_np(pthread_), priority);
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if (result != 0) {
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PLOG(ERROR) << "Failed to setpriority to :" << priority;
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}
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#else
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UNUSED(priority);
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#endif
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}
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int ThreadPoolWorker::GetPthreadPriority() {
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#if defined(ART_TARGET_ANDROID)
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return getpriority(PRIO_PROCESS, pthread_gettid_np(pthread_));
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#else
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return 0;
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#endif
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}
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void ThreadPoolWorker::Run() {
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Thread* self = Thread::Current();
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Task* task = nullptr;
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thread_pool_->creation_barier_.Pass(self);
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while ((task = thread_pool_->GetTask(self)) != nullptr) {
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task->Run(self);
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task->Finalize();
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}
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}
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void* ThreadPoolWorker::Callback(void* arg) {
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ThreadPoolWorker* worker = reinterpret_cast<ThreadPoolWorker*>(arg);
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Runtime* runtime = Runtime::Current();
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CHECK(runtime->AttachCurrentThread(
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worker->name_.c_str(),
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true,
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// Thread-groups are only tracked by the peer j.l.Thread objects. If we aren't creating peers
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// we don't need to specify the thread group. We want to place these threads in the System
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// thread group because that thread group is where important threads that debuggers and
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// similar tools should not mess with are placed. As this is an internal-thread-pool we might
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// rely on being able to (for example) wait for all threads to finish some task. If debuggers
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// are suspending these threads that might not be possible.
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worker->thread_pool_->create_peers_ ? runtime->GetSystemThreadGroup() : nullptr,
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worker->thread_pool_->create_peers_));
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worker->thread_ = Thread::Current();
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// Mark thread pool workers as runtime-threads.
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worker->thread_->SetIsRuntimeThread(true);
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// Do work until its time to shut down.
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worker->Run();
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runtime->DetachCurrentThread();
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return nullptr;
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}
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void ThreadPool::AddTask(Thread* self, Task* task) {
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MutexLock mu(self, task_queue_lock_);
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tasks_.push_back(task);
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// If we have any waiters, signal one.
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if (started_ && waiting_count_ != 0) {
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task_queue_condition_.Signal(self);
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}
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}
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void ThreadPool::RemoveAllTasks(Thread* self) {
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// The ThreadPool is responsible for calling Finalize (which usually delete
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// the task memory) on all the tasks.
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Task* task = nullptr;
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while ((task = TryGetTask(self)) != nullptr) {
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task->Finalize();
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}
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MutexLock mu(self, task_queue_lock_);
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tasks_.clear();
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}
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ThreadPool::ThreadPool(const char* name,
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size_t num_threads,
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bool create_peers,
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size_t worker_stack_size)
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: name_(name),
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task_queue_lock_("task queue lock", kGenericBottomLock),
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task_queue_condition_("task queue condition", task_queue_lock_),
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completion_condition_("task completion condition", task_queue_lock_),
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started_(false),
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shutting_down_(false),
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waiting_count_(0),
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start_time_(0),
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total_wait_time_(0),
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creation_barier_(0),
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max_active_workers_(num_threads),
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create_peers_(create_peers),
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worker_stack_size_(worker_stack_size) {
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CreateThreads();
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}
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void ThreadPool::CreateThreads() {
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CHECK(threads_.empty());
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Thread* self = Thread::Current();
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{
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MutexLock mu(self, task_queue_lock_);
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shutting_down_ = false;
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// Add one since the caller of constructor waits on the barrier too.
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creation_barier_.Init(self, max_active_workers_);
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while (GetThreadCount() < max_active_workers_) {
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const std::string worker_name = StringPrintf("%s worker thread %zu", name_.c_str(),
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GetThreadCount());
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threads_.push_back(
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new ThreadPoolWorker(this, worker_name, worker_stack_size_));
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}
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}
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}
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void ThreadPool::WaitForWorkersToBeCreated() {
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creation_barier_.Increment(Thread::Current(), 0);
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}
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const std::vector<ThreadPoolWorker*>& ThreadPool::GetWorkers() {
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// Wait for all the workers to be created before returning them.
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WaitForWorkersToBeCreated();
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return threads_;
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}
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void ThreadPool::DeleteThreads() {
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{
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Thread* self = Thread::Current();
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MutexLock mu(self, task_queue_lock_);
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// Tell any remaining workers to shut down.
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shutting_down_ = true;
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// Broadcast to everyone waiting.
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task_queue_condition_.Broadcast(self);
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completion_condition_.Broadcast(self);
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}
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// Wait for the threads to finish. We expect the user of the pool
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// not to run multi-threaded calls to `CreateThreads` and `DeleteThreads`,
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// so we don't guard the field here.
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STLDeleteElements(&threads_);
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}
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void ThreadPool::SetMaxActiveWorkers(size_t max_workers) {
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MutexLock mu(Thread::Current(), task_queue_lock_);
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CHECK_LE(max_workers, GetThreadCount());
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max_active_workers_ = max_workers;
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}
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ThreadPool::~ThreadPool() {
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DeleteThreads();
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RemoveAllTasks(Thread::Current());
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}
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void ThreadPool::StartWorkers(Thread* self) {
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MutexLock mu(self, task_queue_lock_);
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started_ = true;
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task_queue_condition_.Broadcast(self);
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start_time_ = NanoTime();
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total_wait_time_ = 0;
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}
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void ThreadPool::StopWorkers(Thread* self) {
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MutexLock mu(self, task_queue_lock_);
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started_ = false;
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}
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Task* ThreadPool::GetTask(Thread* self) {
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MutexLock mu(self, task_queue_lock_);
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while (!IsShuttingDown()) {
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const size_t thread_count = GetThreadCount();
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// Ensure that we don't use more threads than the maximum active workers.
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const size_t active_threads = thread_count - waiting_count_;
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// <= since self is considered an active worker.
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if (active_threads <= max_active_workers_) {
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Task* task = TryGetTaskLocked();
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if (task != nullptr) {
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return task;
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}
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}
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++waiting_count_;
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if (waiting_count_ == GetThreadCount() && !HasOutstandingTasks()) {
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// We may be done, lets broadcast to the completion condition.
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completion_condition_.Broadcast(self);
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}
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const uint64_t wait_start = kMeasureWaitTime ? NanoTime() : 0;
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task_queue_condition_.Wait(self);
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if (kMeasureWaitTime) {
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const uint64_t wait_end = NanoTime();
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total_wait_time_ += wait_end - std::max(wait_start, start_time_);
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}
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--waiting_count_;
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}
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// We are shutting down, return null to tell the worker thread to stop looping.
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return nullptr;
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}
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Task* ThreadPool::TryGetTask(Thread* self) {
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MutexLock mu(self, task_queue_lock_);
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return TryGetTaskLocked();
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}
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Task* ThreadPool::TryGetTaskLocked() {
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if (HasOutstandingTasks()) {
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Task* task = tasks_.front();
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tasks_.pop_front();
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return task;
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}
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return nullptr;
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}
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void ThreadPool::Wait(Thread* self, bool do_work, bool may_hold_locks) {
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if (do_work) {
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CHECK(!create_peers_);
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Task* task = nullptr;
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while ((task = TryGetTask(self)) != nullptr) {
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task->Run(self);
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task->Finalize();
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}
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}
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// Wait until each thread is waiting and the task list is empty.
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MutexLock mu(self, task_queue_lock_);
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while (!shutting_down_ && (waiting_count_ != GetThreadCount() || HasOutstandingTasks())) {
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if (!may_hold_locks) {
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completion_condition_.Wait(self);
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} else {
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completion_condition_.WaitHoldingLocks(self);
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}
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}
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}
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size_t ThreadPool::GetTaskCount(Thread* self) {
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MutexLock mu(self, task_queue_lock_);
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return tasks_.size();
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}
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void ThreadPool::SetPthreadPriority(int priority) {
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for (ThreadPoolWorker* worker : threads_) {
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worker->SetPthreadPriority(priority);
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}
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}
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void ThreadPool::CheckPthreadPriority(int priority) {
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#if defined(ART_TARGET_ANDROID)
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for (ThreadPoolWorker* worker : threads_) {
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CHECK_EQ(worker->GetPthreadPriority(), priority);
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}
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#else
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UNUSED(priority);
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#endif
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}
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} // namespace art
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