Elliott Hughes | 1aa246d | 2012-12-13 09:29:36 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2012 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 17 | #include "thread_pool.h" |
| 18 | |
Elliott Hughes | 1aa246d | 2012-12-13 09:29:36 -0800 | [diff] [blame] | 19 | #include "base/casts.h" |
| 20 | #include "base/stl_util.h" |
| 21 | #include "runtime.h" |
Brian Carlstrom | a3d2718 | 2013-11-05 23:22:27 -0800 | [diff] [blame] | 22 | #include "thread-inl.h" |
Elliott Hughes | 1aa246d | 2012-12-13 09:29:36 -0800 | [diff] [blame] | 23 | |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 24 | namespace art { |
| 25 | |
Mathieu Chartier | 720ef76 | 2013-08-17 14:46:54 -0700 | [diff] [blame] | 26 | static constexpr bool kMeasureWaitTime = false; |
Mathieu Chartier | 94c32c5 | 2013-08-09 11:14:04 -0700 | [diff] [blame] | 27 | |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 28 | ThreadPoolWorker::ThreadPoolWorker(ThreadPool* thread_pool, const std::string& name, |
| 29 | size_t stack_size) |
| 30 | : thread_pool_(thread_pool), |
Mathieu Chartier | bcd5e9d | 2013-11-13 14:33:28 -0800 | [diff] [blame] | 31 | name_(name) { |
| 32 | std::string error_msg; |
| 33 | stack_.reset(MemMap::MapAnonymous(name.c_str(), nullptr, stack_size, PROT_READ | PROT_WRITE, |
| 34 | &error_msg)); |
| 35 | CHECK(stack_.get() != nullptr) << error_msg; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 36 | const char* reason = "new thread pool worker thread"; |
Brian Carlstrom | bcc2926 | 2012-11-02 11:36:03 -0700 | [diff] [blame] | 37 | pthread_attr_t attr; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 38 | CHECK_PTHREAD_CALL(pthread_attr_init, (&attr), reason); |
Mathieu Chartier | bcd5e9d | 2013-11-13 14:33:28 -0800 | [diff] [blame] | 39 | CHECK_PTHREAD_CALL(pthread_attr_setstack, (&attr, stack_->Begin(), stack_->Size()), reason); |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 40 | CHECK_PTHREAD_CALL(pthread_create, (&pthread_, &attr, &Callback, this), reason); |
| 41 | CHECK_PTHREAD_CALL(pthread_attr_destroy, (&attr), reason); |
| 42 | } |
| 43 | |
| 44 | ThreadPoolWorker::~ThreadPoolWorker() { |
| 45 | CHECK_PTHREAD_CALL(pthread_join, (pthread_, NULL), "thread pool worker shutdown"); |
| 46 | } |
| 47 | |
| 48 | void ThreadPoolWorker::Run() { |
| 49 | Thread* self = Thread::Current(); |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 50 | Task* task = NULL; |
Mathieu Chartier | 35883cc | 2012-11-13 14:08:12 -0800 | [diff] [blame] | 51 | thread_pool_->creation_barier_.Wait(self); |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 52 | while ((task = thread_pool_->GetTask(self)) != NULL) { |
| 53 | task->Run(self); |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 54 | task->Finalize(); |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 55 | } |
| 56 | } |
| 57 | |
| 58 | void* ThreadPoolWorker::Callback(void* arg) { |
| 59 | ThreadPoolWorker* worker = reinterpret_cast<ThreadPoolWorker*>(arg); |
| 60 | Runtime* runtime = Runtime::Current(); |
Mathieu Chartier | 664bebf | 2012-11-12 16:54:11 -0800 | [diff] [blame] | 61 | CHECK(runtime->AttachCurrentThread(worker->name_.c_str(), true, NULL, false)); |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 62 | // Do work until its time to shut down. |
| 63 | worker->Run(); |
| 64 | runtime->DetachCurrentThread(); |
| 65 | return NULL; |
| 66 | } |
| 67 | |
Brian Carlstrom | 2ce745c | 2013-07-17 17:44:30 -0700 | [diff] [blame] | 68 | void ThreadPool::AddTask(Thread* self, Task* task) { |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 69 | MutexLock mu(self, task_queue_lock_); |
| 70 | tasks_.push_back(task); |
| 71 | // If we have any waiters, signal one. |
Mathieu Chartier | 94c32c5 | 2013-08-09 11:14:04 -0700 | [diff] [blame] | 72 | if (started_ && waiting_count_ != 0) { |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 73 | task_queue_condition_.Signal(self); |
| 74 | } |
| 75 | } |
| 76 | |
Mathieu Chartier | bcd5e9d | 2013-11-13 14:33:28 -0800 | [diff] [blame] | 77 | ThreadPool::ThreadPool(const char* name, size_t num_threads) |
| 78 | : name_(name), |
| 79 | task_queue_lock_("task queue lock"), |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 80 | task_queue_condition_("task queue condition", task_queue_lock_), |
| 81 | completion_condition_("task completion condition", task_queue_lock_), |
| 82 | started_(false), |
| 83 | shutting_down_(false), |
Mathieu Chartier | 35883cc | 2012-11-13 14:08:12 -0800 | [diff] [blame] | 84 | waiting_count_(0), |
Ian Rogers | d914eb2 | 2013-04-18 16:11:15 -0700 | [diff] [blame] | 85 | start_time_(0), |
| 86 | total_wait_time_(0), |
Mathieu Chartier | 35883cc | 2012-11-13 14:08:12 -0800 | [diff] [blame] | 87 | // Add one since the caller of constructor waits on the barrier too. |
Mathieu Chartier | 2775ee4 | 2013-08-20 17:43:47 -0700 | [diff] [blame] | 88 | creation_barier_(num_threads + 1), |
| 89 | max_active_workers_(num_threads) { |
Mathieu Chartier | 35883cc | 2012-11-13 14:08:12 -0800 | [diff] [blame] | 90 | Thread* self = Thread::Current(); |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 91 | while (GetThreadCount() < num_threads) { |
Mathieu Chartier | bcd5e9d | 2013-11-13 14:33:28 -0800 | [diff] [blame] | 92 | const std::string name = StringPrintf("%s worker thread %zu", name_.c_str(), GetThreadCount()); |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 93 | threads_.push_back(new ThreadPoolWorker(this, name, ThreadPoolWorker::kDefaultStackSize)); |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 94 | } |
Mathieu Chartier | 35883cc | 2012-11-13 14:08:12 -0800 | [diff] [blame] | 95 | // Wait for all of the threads to attach. |
| 96 | creation_barier_.Wait(self); |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 97 | } |
| 98 | |
Mathieu Chartier | 2775ee4 | 2013-08-20 17:43:47 -0700 | [diff] [blame] | 99 | void ThreadPool::SetMaxActiveWorkers(size_t threads) { |
| 100 | MutexLock mu(Thread::Current(), task_queue_lock_); |
| 101 | CHECK_LE(threads, GetThreadCount()); |
| 102 | max_active_workers_ = threads; |
| 103 | } |
| 104 | |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 105 | ThreadPool::~ThreadPool() { |
Mathieu Chartier | e46cd75 | 2012-10-31 16:56:18 -0700 | [diff] [blame] | 106 | { |
| 107 | Thread* self = Thread::Current(); |
| 108 | MutexLock mu(self, task_queue_lock_); |
| 109 | // Tell any remaining workers to shut down. |
| 110 | shutting_down_ = true; |
Mathieu Chartier | e46cd75 | 2012-10-31 16:56:18 -0700 | [diff] [blame] | 111 | // Broadcast to everyone waiting. |
| 112 | task_queue_condition_.Broadcast(self); |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 113 | completion_condition_.Broadcast(self); |
Mathieu Chartier | e46cd75 | 2012-10-31 16:56:18 -0700 | [diff] [blame] | 114 | } |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 115 | // Wait for the threads to finish. |
| 116 | STLDeleteElements(&threads_); |
| 117 | } |
| 118 | |
| 119 | void ThreadPool::StartWorkers(Thread* self) { |
| 120 | MutexLock mu(self, task_queue_lock_); |
| 121 | started_ = true; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 122 | task_queue_condition_.Broadcast(self); |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 123 | start_time_ = NanoTime(); |
| 124 | total_wait_time_ = 0; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 125 | } |
| 126 | |
| 127 | void ThreadPool::StopWorkers(Thread* self) { |
| 128 | MutexLock mu(self, task_queue_lock_); |
| 129 | started_ = false; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 130 | } |
| 131 | |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 132 | Task* ThreadPool::GetTask(Thread* self) { |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 133 | MutexLock mu(self, task_queue_lock_); |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 134 | while (!IsShuttingDown()) { |
Mathieu Chartier | 2775ee4 | 2013-08-20 17:43:47 -0700 | [diff] [blame] | 135 | const size_t thread_count = GetThreadCount(); |
| 136 | // Ensure that we don't use more threads than the maximum active workers. |
| 137 | const size_t active_threads = thread_count - waiting_count_; |
| 138 | // <= since self is considered an active worker. |
| 139 | if (active_threads <= max_active_workers_) { |
| 140 | Task* task = TryGetTaskLocked(self); |
| 141 | if (task != NULL) { |
| 142 | return task; |
| 143 | } |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 144 | } |
| 145 | |
Mathieu Chartier | 2775ee4 | 2013-08-20 17:43:47 -0700 | [diff] [blame] | 146 | ++waiting_count_; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 147 | if (waiting_count_ == GetThreadCount() && tasks_.empty()) { |
| 148 | // We may be done, lets broadcast to the completion condition. |
| 149 | completion_condition_.Broadcast(self); |
| 150 | } |
Mathieu Chartier | 94c32c5 | 2013-08-09 11:14:04 -0700 | [diff] [blame] | 151 | const uint64_t wait_start = kMeasureWaitTime ? NanoTime() : 0; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 152 | task_queue_condition_.Wait(self); |
Mathieu Chartier | 94c32c5 | 2013-08-09 11:14:04 -0700 | [diff] [blame] | 153 | if (kMeasureWaitTime) { |
| 154 | const uint64_t wait_end = NanoTime(); |
| 155 | total_wait_time_ += wait_end - std::max(wait_start, start_time_); |
| 156 | } |
| 157 | --waiting_count_; |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 158 | } |
| 159 | |
| 160 | // We are shutting down, return NULL to tell the worker thread to stop looping. |
| 161 | return NULL; |
| 162 | } |
| 163 | |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 164 | Task* ThreadPool::TryGetTask(Thread* self) { |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 165 | MutexLock mu(self, task_queue_lock_); |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 166 | return TryGetTaskLocked(self); |
| 167 | } |
| 168 | |
| 169 | Task* ThreadPool::TryGetTaskLocked(Thread* self) { |
| 170 | if (started_ && !tasks_.empty()) { |
| 171 | Task* task = tasks_.front(); |
| 172 | tasks_.pop_front(); |
| 173 | return task; |
| 174 | } |
| 175 | return NULL; |
| 176 | } |
| 177 | |
Ian Rogers | 1d54e73 | 2013-05-02 21:10:01 -0700 | [diff] [blame] | 178 | void ThreadPool::Wait(Thread* self, bool do_work, bool may_hold_locks) { |
| 179 | if (do_work) { |
| 180 | Task* task = NULL; |
| 181 | while ((task = TryGetTask(self)) != NULL) { |
| 182 | task->Run(self); |
| 183 | task->Finalize(); |
| 184 | } |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 185 | } |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 186 | // Wait until each thread is waiting and the task list is empty. |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 187 | MutexLock mu(self, task_queue_lock_); |
| 188 | while (!shutting_down_ && (waiting_count_ != GetThreadCount() || !tasks_.empty())) { |
Ian Rogers | 1d54e73 | 2013-05-02 21:10:01 -0700 | [diff] [blame] | 189 | if (!may_hold_locks) { |
| 190 | completion_condition_.Wait(self); |
| 191 | } else { |
| 192 | completion_condition_.WaitHoldingLocks(self); |
| 193 | } |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 194 | } |
| 195 | } |
| 196 | |
Brian Carlstrom | 2ce745c | 2013-07-17 17:44:30 -0700 | [diff] [blame] | 197 | size_t ThreadPool::GetTaskCount(Thread* self) { |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 198 | MutexLock mu(self, task_queue_lock_); |
| 199 | return tasks_.size(); |
| 200 | } |
| 201 | |
| 202 | WorkStealingWorker::WorkStealingWorker(ThreadPool* thread_pool, const std::string& name, |
| 203 | size_t stack_size) |
Brian Carlstrom | 0cd7ec2 | 2013-07-17 23:40:20 -0700 | [diff] [blame] | 204 | : ThreadPoolWorker(thread_pool, name, stack_size), task_(NULL) {} |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 205 | |
| 206 | void WorkStealingWorker::Run() { |
| 207 | Thread* self = Thread::Current(); |
| 208 | Task* task = NULL; |
| 209 | WorkStealingThreadPool* thread_pool = down_cast<WorkStealingThreadPool*>(thread_pool_); |
| 210 | while ((task = thread_pool_->GetTask(self)) != NULL) { |
| 211 | WorkStealingTask* stealing_task = down_cast<WorkStealingTask*>(task); |
| 212 | |
| 213 | { |
| 214 | CHECK(task_ == NULL); |
| 215 | MutexLock mu(self, thread_pool->work_steal_lock_); |
| 216 | // Register that we are running the task |
| 217 | ++stealing_task->ref_count_; |
| 218 | task_ = stealing_task; |
| 219 | } |
| 220 | stealing_task->Run(self); |
| 221 | // Mark ourselves as not running a task so that nobody tries to steal from us. |
| 222 | // There is a race condition that someone starts stealing from us at this point. This is okay |
| 223 | // due to the reference counting. |
| 224 | task_ = NULL; |
| 225 | |
| 226 | bool finalize; |
| 227 | |
| 228 | // Steal work from tasks until there is none left to steal. Note: There is a race, but |
| 229 | // all that happens when the race occurs is that we steal some work instead of processing a |
| 230 | // task from the queue. |
| 231 | while (thread_pool->GetTaskCount(self) == 0) { |
| 232 | WorkStealingTask* steal_from_task = NULL; |
| 233 | |
| 234 | { |
| 235 | MutexLock mu(self, thread_pool->work_steal_lock_); |
| 236 | // Try finding a task to steal from. |
| 237 | steal_from_task = thread_pool->FindTaskToStealFrom(self); |
| 238 | if (steal_from_task != NULL) { |
| 239 | CHECK_NE(stealing_task, steal_from_task) |
| 240 | << "Attempting to steal from completed self task"; |
| 241 | steal_from_task->ref_count_++; |
| 242 | } else { |
| 243 | break; |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | if (steal_from_task != NULL) { |
| 248 | // Task which completed earlier is going to steal some work. |
| 249 | stealing_task->StealFrom(self, steal_from_task); |
| 250 | |
| 251 | { |
| 252 | // We are done stealing from the task, lets decrement its reference count. |
| 253 | MutexLock mu(self, thread_pool->work_steal_lock_); |
| 254 | finalize = !--steal_from_task->ref_count_; |
| 255 | } |
| 256 | |
| 257 | if (finalize) { |
| 258 | steal_from_task->Finalize(); |
| 259 | } |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | { |
| 264 | MutexLock mu(self, thread_pool->work_steal_lock_); |
| 265 | // If nobody is still referencing task_ we can finalize it. |
| 266 | finalize = !--stealing_task->ref_count_; |
| 267 | } |
| 268 | |
| 269 | if (finalize) { |
| 270 | stealing_task->Finalize(); |
| 271 | } |
| 272 | } |
| 273 | } |
| 274 | |
Brian Carlstrom | 0cd7ec2 | 2013-07-17 23:40:20 -0700 | [diff] [blame] | 275 | WorkStealingWorker::~WorkStealingWorker() {} |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 276 | |
Mathieu Chartier | bcd5e9d | 2013-11-13 14:33:28 -0800 | [diff] [blame] | 277 | WorkStealingThreadPool::WorkStealingThreadPool(const char* name, size_t num_threads) |
| 278 | : ThreadPool(name, 0), |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 279 | work_steal_lock_("work stealing lock"), |
| 280 | steal_index_(0) { |
| 281 | while (GetThreadCount() < num_threads) { |
| 282 | const std::string name = StringPrintf("Work stealing worker %zu", GetThreadCount()); |
| 283 | threads_.push_back(new WorkStealingWorker(this, name, ThreadPoolWorker::kDefaultStackSize)); |
| 284 | } |
| 285 | } |
| 286 | |
| 287 | WorkStealingTask* WorkStealingThreadPool::FindTaskToStealFrom(Thread* self) { |
| 288 | const size_t thread_count = GetThreadCount(); |
| 289 | for (size_t i = 0; i < thread_count; ++i) { |
| 290 | // TODO: Use CAS instead of lock. |
| 291 | ++steal_index_; |
| 292 | if (steal_index_ >= thread_count) { |
| 293 | steal_index_-= thread_count; |
| 294 | } |
| 295 | |
| 296 | WorkStealingWorker* worker = down_cast<WorkStealingWorker*>(threads_[steal_index_]); |
| 297 | WorkStealingTask* task = worker->task_; |
| 298 | if (task) { |
| 299 | // Not null, we can probably steal from this worker. |
| 300 | return task; |
| 301 | } |
| 302 | } |
| 303 | // Couldn't find something to steal. |
| 304 | return NULL; |
| 305 | } |
| 306 | |
Brian Carlstrom | 0cd7ec2 | 2013-07-17 23:40:20 -0700 | [diff] [blame] | 307 | WorkStealingThreadPool::~WorkStealingThreadPool() {} |
Mathieu Chartier | 02b6a78 | 2012-10-26 13:51:26 -0700 | [diff] [blame] | 308 | |
Mathieu Chartier | 0e4627e | 2012-10-23 16:13:36 -0700 | [diff] [blame] | 309 | } // namespace art |