| // Copyright 2016 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "base/task/thread_pool/thread_group_impl.h" |
| |
| #include <stddef.h> |
| |
| #include <algorithm> |
| #include <type_traits> |
| #include <utility> |
| |
| #include "base/atomicops.h" |
| #include "base/auto_reset.h" |
| #include "base/bind.h" |
| #include "base/bind_helpers.h" |
| #include "base/compiler_specific.h" |
| #include "base/feature_list.h" |
| #include "base/location.h" |
| #include "base/memory/ptr_util.h" |
| #include "base/metrics/histogram.h" |
| #include "base/numerics/clamped_math.h" |
| #include "base/optional.h" |
| #include "base/sequence_token.h" |
| #include "base/strings/string_util.h" |
| #include "base/strings/stringprintf.h" |
| #include "base/task/task_features.h" |
| #include "base/task/task_traits.h" |
| #include "base/task/thread_pool/task_tracker.h" |
| #include "base/threading/platform_thread.h" |
| #include "base/threading/scoped_blocking_call.h" |
| #include "base/threading/thread_checker.h" |
| #include "base/threading/thread_restrictions.h" |
| #include "base/time/time_override.h" |
| #include "build/build_config.h" |
| |
| #if defined(OS_WIN) |
| #include "base/win/scoped_com_initializer.h" |
| #include "base/win/scoped_windows_thread_environment.h" |
| #include "base/win/scoped_winrt_initializer.h" |
| #include "base/win/windows_version.h" |
| #endif // defined(OS_WIN) |
| |
| namespace base { |
| namespace internal { |
| |
| namespace { |
| |
| constexpr char kDetachDurationHistogramPrefix[] = "ThreadPool.DetachDuration."; |
| constexpr char kNumTasksBeforeDetachHistogramPrefix[] = |
| "ThreadPool.NumTasksBeforeDetach."; |
| constexpr char kNumTasksBetweenWaitsHistogramPrefix[] = |
| "ThreadPool.NumTasksBetweenWaits."; |
| constexpr char kNumWorkersHistogramPrefix[] = "ThreadPool.NumWorkers."; |
| constexpr char kNumActiveWorkersHistogramPrefix[] = |
| "ThreadPool.NumActiveWorkers."; |
| constexpr size_t kMaxNumberOfWorkers = 256; |
| |
| // In a background thread group: |
| // - Blocking calls take more time than in a foreground thread group. |
| // - We want to minimize impact on foreground work, not maximize execution |
| // throughput. |
| // For these reasons, the timeout to increase the maximum number of concurrent |
| // tasks when there is a MAY_BLOCK ScopedBlockingCall is *long*. It is not |
| // infinite because execution throughput should not be reduced forever if a task |
| // blocks forever. |
| // |
| // TODO(fdoray): On platforms without background thread groups, blocking in a |
| // BEST_EFFORT task should: |
| // 1. Increment the maximum number of concurrent tasks after a *short* timeout, |
| // to allow scheduling of USER_VISIBLE/USER_BLOCKING tasks. |
| // 2. Increment the maximum number of concurrent BEST_EFFORT tasks after a |
| // *long* timeout, because we only want to allow more BEST_EFFORT tasks to be |
| // be scheduled concurrently when we believe that a BEST_EFFORT task is |
| // blocked forever. |
| // Currently, only 1. is true as the configuration is per thread group. |
| // TODO(https://crbug.com/927755): Fix racy condition when MayBlockThreshold == |
| // BlockedWorkersPoll. |
| constexpr TimeDelta kForegroundMayBlockThreshold = |
| TimeDelta::FromMilliseconds(1000); |
| constexpr TimeDelta kForegroundBlockedWorkersPoll = |
| TimeDelta::FromMilliseconds(1200); |
| constexpr TimeDelta kBackgroundMayBlockThreshold = TimeDelta::FromSeconds(10); |
| constexpr TimeDelta kBackgroundBlockedWorkersPoll = TimeDelta::FromSeconds(12); |
| |
| // Only used in DCHECKs. |
| bool ContainsWorker(const std::vector<scoped_refptr<WorkerThread>>& workers, |
| const WorkerThread* worker) { |
| auto it = std::find_if(workers.begin(), workers.end(), |
| [worker](const scoped_refptr<WorkerThread>& i) { |
| return i.get() == worker; |
| }); |
| return it != workers.end(); |
| } |
| |
| } // namespace |
| |
| // Upon destruction, executes actions that control the number of active workers. |
| // Useful to satisfy locking requirements of these actions. |
| class ThreadGroupImpl::ScopedWorkersExecutor |
| : public ThreadGroup::BaseScopedWorkersExecutor { |
| public: |
| ScopedWorkersExecutor(ThreadGroupImpl* outer) : outer_(outer) {} |
| |
| ~ScopedWorkersExecutor() { FlushImpl(); } |
| |
| void ScheduleWakeUp(scoped_refptr<WorkerThread> worker) { |
| workers_to_wake_up_.AddWorker(std::move(worker)); |
| } |
| |
| void ScheduleStart(scoped_refptr<WorkerThread> worker) { |
| workers_to_start_.AddWorker(std::move(worker)); |
| } |
| |
| void FlushWorkerCreation(CheckedLock* held_lock) { |
| if (workers_to_wake_up_.empty() && workers_to_start_.empty()) |
| return; |
| CheckedAutoUnlock auto_unlock(*held_lock); |
| FlushImpl(); |
| workers_to_wake_up_.clear(); |
| workers_to_start_.clear(); |
| must_schedule_adjust_max_tasks_ = false; |
| } |
| |
| void ScheduleAdjustMaxTasks() { |
| DCHECK(!must_schedule_adjust_max_tasks_); |
| must_schedule_adjust_max_tasks_ = true; |
| } |
| |
| private: |
| class WorkerContainer { |
| public: |
| WorkerContainer() = default; |
| |
| void AddWorker(scoped_refptr<WorkerThread> worker) { |
| if (!worker) |
| return; |
| if (!first_worker_) |
| first_worker_ = std::move(worker); |
| else |
| additional_workers_.push_back(std::move(worker)); |
| } |
| |
| template <typename Action> |
| void ForEachWorker(Action action) { |
| if (first_worker_) { |
| action(first_worker_.get()); |
| for (scoped_refptr<WorkerThread> worker : additional_workers_) |
| action(worker.get()); |
| } else { |
| DCHECK(additional_workers_.empty()); |
| } |
| } |
| |
| bool empty() const { return first_worker_ == nullptr; } |
| |
| void clear() { |
| first_worker_.reset(); |
| additional_workers_.clear(); |
| } |
| |
| private: |
| // The purpose of |first_worker| is to avoid a heap allocation by the vector |
| // in the case where there is only one worker in the container. |
| scoped_refptr<WorkerThread> first_worker_; |
| std::vector<scoped_refptr<WorkerThread>> additional_workers_; |
| |
| DISALLOW_COPY_AND_ASSIGN(WorkerContainer); |
| }; |
| |
| void FlushImpl() { |
| CheckedLock::AssertNoLockHeldOnCurrentThread(); |
| |
| // Wake up workers. |
| workers_to_wake_up_.ForEachWorker( |
| [](WorkerThread* worker) { worker->WakeUp(); }); |
| |
| // Start workers. Happens after wake ups to prevent the case where a worker |
| // enters its main function, is descheduled because it wasn't woken up yet, |
| // and is woken up immediately after. |
| workers_to_start_.ForEachWorker([&](WorkerThread* worker) { |
| worker->Start(outer_->after_start().worker_thread_observer); |
| }); |
| |
| if (must_schedule_adjust_max_tasks_) |
| outer_->ScheduleAdjustMaxTasks(); |
| } |
| |
| ThreadGroupImpl* const outer_; |
| |
| WorkerContainer workers_to_wake_up_; |
| WorkerContainer workers_to_start_; |
| bool must_schedule_adjust_max_tasks_ = false; |
| |
| DISALLOW_COPY_AND_ASSIGN(ScopedWorkersExecutor); |
| }; |
| |
| class ThreadGroupImpl::WorkerThreadDelegateImpl : public WorkerThread::Delegate, |
| public BlockingObserver { |
| public: |
| // |outer| owns the worker for which this delegate is constructed. |
| WorkerThreadDelegateImpl(TrackedRef<ThreadGroupImpl> outer); |
| ~WorkerThreadDelegateImpl() override; |
| |
| // WorkerThread::Delegate: |
| WorkerThread::ThreadLabel GetThreadLabel() const override; |
| void OnMainEntry(const WorkerThread* worker) override; |
| RunIntentWithRegisteredTaskSource GetWork(WorkerThread* worker) override; |
| void DidProcessTask(RegisteredTaskSource task_source) override; |
| TimeDelta GetSleepTimeout() override; |
| void OnMainExit(WorkerThread* worker) override; |
| |
| // BlockingObserver: |
| void BlockingStarted(BlockingType blocking_type) override; |
| void BlockingTypeUpgraded() override; |
| void BlockingEnded() override; |
| |
| void MayBlockEntered(); |
| void WillBlockEntered(); |
| |
| // Returns true iff the worker can get work. Cleans up the worker or puts it |
| // on the idle stack if it can't get work. |
| bool CanGetWorkLockRequired(WorkerThread* worker) |
| EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_); |
| |
| // Returns true iff this worker has been within a MAY_BLOCK ScopedBlockingCall |
| // for more than |may_block_threshold|. The max tasks must be |
| // incremented if this returns true. |
| bool MustIncrementMaxTasksLockRequired() |
| EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_); |
| |
| TaskPriority current_task_priority_lock_required() const |
| EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_) { |
| return *read_any().current_task_priority; |
| } |
| |
| // Exposed for AnnotateCheckedLockAcquired in |
| // ThreadGroupImpl::AdjustMaxTasks() |
| const CheckedLock& lock() const LOCK_RETURNED(outer_->lock_) { |
| return outer_->lock_; |
| } |
| |
| private: |
| // Returns true if |worker| is allowed to cleanup and remove itself from the |
| // thread group. Called from GetWork() when no work is available. |
| bool CanCleanupLockRequired(const WorkerThread* worker) const |
| EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_); |
| |
| // Calls cleanup on |worker| and removes it from the thread group. Called from |
| // GetWork() when no work is available and CanCleanupLockRequired() returns |
| // true. |
| void CleanupLockRequired(WorkerThread* worker) |
| EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_); |
| |
| // Called in GetWork() when a worker becomes idle. |
| void OnWorkerBecomesIdleLockRequired(WorkerThread* worker) |
| EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_); |
| |
| // Accessed only from the worker thread. |
| struct WorkerOnly { |
| // Number of tasks executed since the last time the |
| // ThreadPool.NumTasksBetweenWaits histogram was recorded. |
| size_t num_tasks_since_last_wait = 0; |
| |
| // Number of tasks executed since the last time the |
| // ThreadPool.NumTasksBeforeDetach histogram was recorded. |
| size_t num_tasks_since_last_detach = 0; |
| |
| // Whether the worker is currently running a task (i.e. GetWork() has |
| // returned a non-empty task source and DidProcessTask() hasn't been called |
| // yet). |
| bool is_running_task = false; |
| |
| #if defined(OS_WIN) |
| std::unique_ptr<win::ScopedWindowsThreadEnvironment> win_thread_environment; |
| #endif // defined(OS_WIN) |
| } worker_only_; |
| |
| // Writes from the worker thread protected by |outer_->lock_|. Reads from any |
| // thread, protected by |outer_->lock_| when not on the worker thread. |
| struct WriteWorkerReadAny { |
| // The priority of the task the worker is currently running if any. |
| base::Optional<TaskPriority> current_task_priority; |
| |
| // Time when MayBlockScopeEntered() was last called. Reset when |
| // BlockingScopeExited() is called. |
| TimeTicks may_block_start_time; |
| } write_worker_read_any_; |
| |
| WorkerOnly& worker_only() { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| return worker_only_; |
| } |
| |
| WriteWorkerReadAny& write_worker() EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| return write_worker_read_any_; |
| } |
| |
| const WriteWorkerReadAny& read_any() const |
| EXCLUSIVE_LOCKS_REQUIRED(outer_->lock_) { |
| return write_worker_read_any_; |
| } |
| |
| const WriteWorkerReadAny& read_worker() const { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| return write_worker_read_any_; |
| } |
| |
| const TrackedRef<ThreadGroupImpl> outer_; |
| |
| // Whether |outer_->max_tasks_| was incremented due to a ScopedBlockingCall on |
| // the thread. |
| bool incremented_max_tasks_since_blocked_ GUARDED_BY(outer_->lock_) = false; |
| |
| // Verifies that specific calls are always made from the worker thread. |
| THREAD_CHECKER(worker_thread_checker_); |
| |
| DISALLOW_COPY_AND_ASSIGN(WorkerThreadDelegateImpl); |
| }; |
| |
| ThreadGroupImpl::ThreadGroupImpl(StringPiece histogram_label, |
| StringPiece thread_group_label, |
| ThreadPriority priority_hint, |
| TrackedRef<TaskTracker> task_tracker, |
| TrackedRef<Delegate> delegate) |
| : ThreadGroup(std::move(task_tracker), std::move(delegate)), |
| thread_group_label_(thread_group_label.as_string()), |
| priority_hint_(priority_hint), |
| idle_workers_stack_cv_for_testing_(lock_.CreateConditionVariable()), |
| // Mimics the UMA_HISTOGRAM_LONG_TIMES macro. |
| detach_duration_histogram_(Histogram::FactoryTimeGet( |
| JoinString({kDetachDurationHistogramPrefix, histogram_label}, ""), |
| TimeDelta::FromMilliseconds(1), |
| TimeDelta::FromHours(1), |
| 50, |
| HistogramBase::kUmaTargetedHistogramFlag)), |
| // Mimics the UMA_HISTOGRAM_COUNTS_1000 macro. When a worker runs more |
| // than 1000 tasks before detaching, there is no need to know the exact |
| // number of tasks that ran. |
| num_tasks_before_detach_histogram_(Histogram::FactoryGet( |
| JoinString({kNumTasksBeforeDetachHistogramPrefix, histogram_label}, |
| ""), |
| 1, |
| 1000, |
| 50, |
| HistogramBase::kUmaTargetedHistogramFlag)), |
| // Mimics the UMA_HISTOGRAM_COUNTS_100 macro. A WorkerThread is |
| // expected to run between zero and a few tens of tasks between waits. |
| // When it runs more than 100 tasks, there is no need to know the exact |
| // number of tasks that ran. |
| num_tasks_between_waits_histogram_(Histogram::FactoryGet( |
| JoinString({kNumTasksBetweenWaitsHistogramPrefix, histogram_label}, |
| ""), |
| 1, |
| 100, |
| 50, |
| HistogramBase::kUmaTargetedHistogramFlag)), |
| // Mimics the UMA_HISTOGRAM_COUNTS_100 macro. A ThreadGroup is |
| // expected to run between zero and a few tens of workers. |
| // When it runs more than 100 worker, there is no need to know the exact |
| // number of workers that ran. |
| num_workers_histogram_(Histogram::FactoryGet( |
| JoinString({kNumWorkersHistogramPrefix, histogram_label}, ""), |
| 1, |
| 100, |
| 50, |
| HistogramBase::kUmaTargetedHistogramFlag)), |
| num_active_workers_histogram_(Histogram::FactoryGet( |
| JoinString({kNumActiveWorkersHistogramPrefix, histogram_label}, ""), |
| 1, |
| 100, |
| 50, |
| HistogramBase::kUmaTargetedHistogramFlag)), |
| tracked_ref_factory_(this) { |
| DCHECK(!histogram_label.empty()); |
| DCHECK(!thread_group_label_.empty()); |
| } |
| |
| void ThreadGroupImpl::Start( |
| int max_tasks, |
| int max_best_effort_tasks, |
| TimeDelta suggested_reclaim_time, |
| scoped_refptr<TaskRunner> service_thread_task_runner, |
| WorkerThreadObserver* worker_thread_observer, |
| WorkerEnvironment worker_environment, |
| Optional<TimeDelta> may_block_threshold) { |
| DCHECK(!replacement_thread_group_); |
| |
| ScopedWorkersExecutor executor(this); |
| |
| CheckedAutoLock auto_lock(lock_); |
| |
| DCHECK(workers_.empty()); |
| |
| in_start().may_block_without_delay = |
| FeatureList::IsEnabled(kMayBlockWithoutDelay); |
| in_start().may_block_threshold = |
| may_block_threshold ? may_block_threshold.value() |
| : (priority_hint_ == ThreadPriority::NORMAL |
| ? kForegroundMayBlockThreshold |
| : kBackgroundMayBlockThreshold); |
| in_start().blocked_workers_poll_period = |
| priority_hint_ == ThreadPriority::NORMAL ? kForegroundBlockedWorkersPoll |
| : kBackgroundBlockedWorkersPoll; |
| |
| max_tasks_ = max_tasks; |
| DCHECK_GE(max_tasks_, 1U); |
| in_start().initial_max_tasks = max_tasks_; |
| DCHECK_LE(in_start().initial_max_tasks, kMaxNumberOfWorkers); |
| max_best_effort_tasks_ = max_best_effort_tasks; |
| in_start().suggested_reclaim_time = suggested_reclaim_time; |
| in_start().worker_environment = worker_environment; |
| in_start().service_thread_task_runner = std::move(service_thread_task_runner); |
| in_start().worker_thread_observer = worker_thread_observer; |
| |
| #if DCHECK_IS_ON() |
| in_start().initialized = true; |
| #endif |
| |
| EnsureEnoughWorkersLockRequired(&executor); |
| } |
| |
| ThreadGroupImpl::~ThreadGroupImpl() { |
| // ThreadGroup should only ever be deleted: |
| // 1) In tests, after JoinForTesting(). |
| // 2) In production, iff initialization failed. |
| // In both cases |workers_| should be empty. |
| DCHECK(workers_.empty()); |
| } |
| |
| void ThreadGroupImpl::UpdateSortKey( |
| TransactionWithOwnedTaskSource transaction_with_task_source) { |
| ScopedWorkersExecutor executor(this); |
| UpdateSortKeyImpl(&executor, std::move(transaction_with_task_source)); |
| } |
| |
| void ThreadGroupImpl::PushTaskSourceAndWakeUpWorkers( |
| TransactionWithRegisteredTaskSource transaction_with_task_source) { |
| ScopedWorkersExecutor executor(this); |
| PushTaskSourceAndWakeUpWorkersImpl(&executor, |
| std::move(transaction_with_task_source)); |
| } |
| |
| size_t ThreadGroupImpl::GetMaxConcurrentNonBlockedTasksDeprecated() const { |
| #if DCHECK_IS_ON() |
| CheckedAutoLock auto_lock(lock_); |
| DCHECK_NE(after_start().initial_max_tasks, 0U) |
| << "GetMaxConcurrentTasksDeprecated() should only be called after the " |
| << "thread group has started."; |
| #endif |
| return after_start().initial_max_tasks; |
| } |
| |
| void ThreadGroupImpl::WaitForWorkersIdleForTesting(size_t n) { |
| CheckedAutoLock auto_lock(lock_); |
| |
| #if DCHECK_IS_ON() |
| DCHECK(!some_workers_cleaned_up_for_testing_) |
| << "Workers detached prior to waiting for a specific number of idle " |
| "workers. Doing the wait under such conditions is flaky. Consider " |
| "setting the suggested reclaim time to TimeDelta::Max() in Start()."; |
| #endif |
| |
| WaitForWorkersIdleLockRequiredForTesting(n); |
| } |
| |
| void ThreadGroupImpl::WaitForAllWorkersIdleForTesting() { |
| CheckedAutoLock auto_lock(lock_); |
| WaitForWorkersIdleLockRequiredForTesting(workers_.size()); |
| } |
| |
| void ThreadGroupImpl::WaitForWorkersCleanedUpForTesting(size_t n) { |
| CheckedAutoLock auto_lock(lock_); |
| |
| if (!num_workers_cleaned_up_for_testing_cv_) |
| num_workers_cleaned_up_for_testing_cv_ = lock_.CreateConditionVariable(); |
| |
| while (num_workers_cleaned_up_for_testing_ < n) |
| num_workers_cleaned_up_for_testing_cv_->Wait(); |
| |
| num_workers_cleaned_up_for_testing_ = 0; |
| } |
| |
| void ThreadGroupImpl::JoinForTesting() { |
| #if DCHECK_IS_ON() |
| join_for_testing_started_.Set(); |
| #endif |
| |
| decltype(workers_) workers_copy; |
| { |
| CheckedAutoLock auto_lock(lock_); |
| priority_queue_.EnableFlushTaskSourcesOnDestroyForTesting(); |
| |
| DCHECK_GT(workers_.size(), size_t(0)) |
| << "Joined an unstarted thread group."; |
| |
| // Ensure WorkerThreads in |workers_| do not attempt to cleanup while |
| // being joined. |
| worker_cleanup_disallowed_for_testing_ = true; |
| |
| // Make a copy of the WorkerThreads so that we can call |
| // WorkerThread::JoinForTesting() without holding |lock_| since |
| // WorkerThreads may need to access |workers_|. |
| workers_copy = workers_; |
| } |
| for (const auto& worker : workers_copy) |
| worker->JoinForTesting(); |
| |
| CheckedAutoLock auto_lock(lock_); |
| DCHECK(workers_ == workers_copy); |
| // Release |workers_| to clear their TrackedRef against |this|. |
| workers_.clear(); |
| } |
| |
| size_t ThreadGroupImpl::NumberOfWorkersForTesting() const { |
| CheckedAutoLock auto_lock(lock_); |
| return workers_.size(); |
| } |
| |
| size_t ThreadGroupImpl::GetMaxTasksForTesting() const { |
| CheckedAutoLock auto_lock(lock_); |
| return max_tasks_; |
| } |
| |
| size_t ThreadGroupImpl::NumberOfIdleWorkersForTesting() const { |
| CheckedAutoLock auto_lock(lock_); |
| return idle_workers_stack_.Size(); |
| } |
| |
| void ThreadGroupImpl::ReportHeartbeatMetrics() const { |
| CheckedAutoLock auto_lock(lock_); |
| num_workers_histogram_->Add(workers_.size()); |
| |
| num_active_workers_histogram_->Add(workers_.size() - |
| idle_workers_stack_.Size()); |
| } |
| |
| ThreadGroupImpl::WorkerThreadDelegateImpl::WorkerThreadDelegateImpl( |
| TrackedRef<ThreadGroupImpl> outer) |
| : outer_(std::move(outer)) { |
| // Bound in OnMainEntry(). |
| DETACH_FROM_THREAD(worker_thread_checker_); |
| } |
| |
| // OnMainExit() handles the thread-affine cleanup; WorkerThreadDelegateImpl |
| // can thereafter safely be deleted from any thread. |
| ThreadGroupImpl::WorkerThreadDelegateImpl::~WorkerThreadDelegateImpl() = |
| default; |
| |
| WorkerThread::ThreadLabel |
| ThreadGroupImpl::WorkerThreadDelegateImpl::GetThreadLabel() const { |
| return WorkerThread::ThreadLabel::POOLED; |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::OnMainEntry( |
| const WorkerThread* worker) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| |
| { |
| #if DCHECK_IS_ON() |
| CheckedAutoLock auto_lock(outer_->lock_); |
| DCHECK(ContainsWorker(outer_->workers_, worker)); |
| #endif |
| } |
| |
| #if defined(OS_WIN) |
| worker_only().win_thread_environment = GetScopedWindowsThreadEnvironment( |
| outer_->after_start().worker_environment); |
| #endif // defined(OS_WIN) |
| |
| DCHECK_EQ(worker_only().num_tasks_since_last_wait, 0U); |
| |
| PlatformThread::SetName( |
| StringPrintf("ThreadPool%sWorker", outer_->thread_group_label_.c_str())); |
| |
| outer_->BindToCurrentThread(); |
| SetBlockingObserverForCurrentThread(this); |
| } |
| |
| RunIntentWithRegisteredTaskSource |
| ThreadGroupImpl::WorkerThreadDelegateImpl::GetWork(WorkerThread* worker) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| DCHECK(!worker_only().is_running_task); |
| |
| ScopedWorkersExecutor executor(outer_.get()); |
| CheckedAutoLock auto_lock(outer_->lock_); |
| |
| DCHECK(ContainsWorker(outer_->workers_, worker)); |
| |
| // Use this opportunity, before assigning work to this worker, to create/wake |
| // additional workers if needed (doing this here allows us to reduce |
| // potentially expensive create/wake directly on PostTask()). |
| outer_->EnsureEnoughWorkersLockRequired(&executor); |
| executor.FlushWorkerCreation(&outer_->lock_); |
| |
| if (!CanGetWorkLockRequired(worker)) |
| return nullptr; |
| |
| RunIntentWithRegisteredTaskSource task_source; |
| TaskPriority priority; |
| while (!task_source && !outer_->priority_queue_.IsEmpty()) { |
| // Enforce the CanRunPolicy and that no more than |max_best_effort_tasks_| |
| // BEST_EFFORT tasks run concurrently. |
| priority = outer_->priority_queue_.PeekSortKey().priority(); |
| if (!outer_->task_tracker_->CanRunPriority(priority) || |
| (priority == TaskPriority::BEST_EFFORT && |
| outer_->num_running_best_effort_tasks_ >= |
| outer_->max_best_effort_tasks_)) { |
| break; |
| } |
| |
| task_source = outer_->TakeRunIntentWithRegisteredTaskSource(&executor); |
| } |
| if (!task_source) { |
| OnWorkerBecomesIdleLockRequired(worker); |
| return nullptr; |
| } |
| |
| // Running task bookkeeping. |
| worker_only().is_running_task = true; |
| outer_->IncrementTasksRunningLockRequired(priority); |
| DCHECK(!outer_->idle_workers_stack_.Contains(worker)); |
| write_worker().current_task_priority = priority; |
| |
| return task_source; |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::DidProcessTask( |
| RegisteredTaskSource task_source) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| DCHECK(worker_only().is_running_task); |
| DCHECK(read_worker().may_block_start_time.is_null()); |
| |
| ++worker_only().num_tasks_since_last_wait; |
| ++worker_only().num_tasks_since_last_detach; |
| |
| // A transaction to the TaskSource to reenqueue, if any. Instantiated here as |
| // |TaskSource::lock_| is a UniversalPredecessor and must always be acquired |
| // prior to acquiring a second lock |
| Optional<TransactionWithRegisteredTaskSource> transaction_with_task_source; |
| if (task_source) { |
| transaction_with_task_source.emplace( |
| TransactionWithRegisteredTaskSource::FromTaskSource( |
| std::move(task_source))); |
| } |
| |
| ScopedWorkersExecutor workers_executor(outer_.get()); |
| ScopedReenqueueExecutor reenqueue_executor; |
| CheckedAutoLock auto_lock(outer_->lock_); |
| |
| DCHECK(!incremented_max_tasks_since_blocked_); |
| |
| // Running task bookkeeping. |
| outer_->DecrementTasksRunningLockRequired( |
| *read_worker().current_task_priority); |
| worker_only().is_running_task = false; |
| |
| if (transaction_with_task_source) { |
| outer_->ReEnqueueTaskSourceLockRequired( |
| &workers_executor, &reenqueue_executor, |
| std::move(transaction_with_task_source.value())); |
| } |
| } |
| |
| TimeDelta ThreadGroupImpl::WorkerThreadDelegateImpl::GetSleepTimeout() { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| // Sleep for an extra 10% to avoid the following pathological case: |
| |
| // 0) A task is running on a timer which matches |
| // |after_start().suggested_reclaim_time|. |
| // 1) The timer fires and this worker is created by |
| // MaintainAtLeastOneIdleWorkerLockRequired() because the last idle |
| // worker was assigned the task. |
| // 2) This worker begins sleeping |after_start().suggested_reclaim_time| (on |
| // top of the idle stack). |
| // 3) The task assigned to the other worker completes and the worker goes |
| // back on the idle stack (this worker is now second on the idle stack; |
| // its GetLastUsedTime() is set to Now()). |
| // 4) The sleep in (2) expires. Since (3) was fast this worker is likely to |
| // have been second on the idle stack long enough for |
| // CanCleanupLockRequired() to be satisfied in which case this worker is |
| // cleaned up. |
| // 5) The timer fires at roughly the same time and we're back to (1) if (4) |
| // resulted in a clean up; causing thread churn. |
| // |
| // Sleeping 10% longer in (2) makes it much less likely that (4) occurs |
| // before (5). In that case (5) will cause (3) and refresh this worker's |
| // GetLastUsedTime(), making CanCleanupLockRequired() return false in (4) |
| // and avoiding churn. |
| // |
| // Of course the same problem arises if in (0) the timer matches |
| // |after_start().suggested_reclaim_time * 1.1| but it's expected that any |
| // timer slower than |after_start().suggested_reclaim_time| will cause such |
| // churn during long idle periods. If this is a problem in practice, the |
| // standby thread configuration and algorithm should be revisited. |
| return outer_->after_start().suggested_reclaim_time * 1.1; |
| } |
| |
| bool ThreadGroupImpl::WorkerThreadDelegateImpl::CanCleanupLockRequired( |
| const WorkerThread* worker) const { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| |
| const TimeTicks last_used_time = worker->GetLastUsedTime(); |
| return !last_used_time.is_null() && |
| subtle::TimeTicksNowIgnoringOverride() - last_used_time >= |
| outer_->after_start().suggested_reclaim_time && |
| (outer_->workers_.size() > outer_->after_start().initial_max_tasks || |
| !FeatureList::IsEnabled(kNoDetachBelowInitialCapacity)) && |
| LIKELY(!outer_->worker_cleanup_disallowed_for_testing_); |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::CleanupLockRequired( |
| WorkerThread* worker) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| |
| outer_->num_tasks_before_detach_histogram_->Add( |
| worker_only().num_tasks_since_last_detach); |
| outer_->cleanup_timestamps_.push(subtle::TimeTicksNowIgnoringOverride()); |
| worker->Cleanup(); |
| outer_->idle_workers_stack_.Remove(worker); |
| |
| // Remove the worker from |workers_|. |
| auto worker_iter = |
| std::find(outer_->workers_.begin(), outer_->workers_.end(), worker); |
| DCHECK(worker_iter != outer_->workers_.end()); |
| outer_->workers_.erase(worker_iter); |
| |
| ++outer_->num_workers_cleaned_up_for_testing_; |
| #if DCHECK_IS_ON() |
| outer_->some_workers_cleaned_up_for_testing_ = true; |
| #endif |
| if (outer_->num_workers_cleaned_up_for_testing_cv_) |
| outer_->num_workers_cleaned_up_for_testing_cv_->Signal(); |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::OnWorkerBecomesIdleLockRequired( |
| WorkerThread* worker) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| |
| // Record the ThreadPool.NumTasksBetweenWaits histogram. After GetWork() |
| // returns nullptr, the WorkerThread will perform a wait on its |
| // WaitableEvent, so we record how many tasks were ran since the last wait |
| // here. |
| outer_->num_tasks_between_waits_histogram_->Add( |
| worker_only().num_tasks_since_last_wait); |
| worker_only().num_tasks_since_last_wait = 0; |
| |
| // Add the worker to the idle stack. |
| DCHECK(!outer_->idle_workers_stack_.Contains(worker)); |
| outer_->idle_workers_stack_.Push(worker); |
| DCHECK_LE(outer_->idle_workers_stack_.Size(), outer_->workers_.size()); |
| outer_->idle_workers_stack_cv_for_testing_->Broadcast(); |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::OnMainExit( |
| WorkerThread* worker) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| |
| #if DCHECK_IS_ON() |
| { |
| bool shutdown_complete = outer_->task_tracker_->IsShutdownComplete(); |
| CheckedAutoLock auto_lock(outer_->lock_); |
| |
| // |worker| should already have been removed from the idle workers stack and |
| // |workers_| by the time the thread is about to exit. (except in the cases |
| // where the thread group is no longer going to be used - in which case, |
| // it's fine for there to be invalid workers in the thread group. |
| if (!shutdown_complete && !outer_->join_for_testing_started_.IsSet()) { |
| DCHECK(!outer_->idle_workers_stack_.Contains(worker)); |
| DCHECK(!ContainsWorker(outer_->workers_, worker)); |
| } |
| } |
| #endif |
| |
| #if defined(OS_WIN) |
| worker_only().win_thread_environment.reset(); |
| #endif // defined(OS_WIN) |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::BlockingStarted( |
| BlockingType blocking_type) { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| DCHECK(worker_only().is_running_task); |
| |
| // MayBlock with no delay reuses WillBlock implementation. |
| if (outer_->after_start().may_block_without_delay) |
| blocking_type = BlockingType::WILL_BLOCK; |
| |
| switch (blocking_type) { |
| case BlockingType::MAY_BLOCK: |
| MayBlockEntered(); |
| break; |
| case BlockingType::WILL_BLOCK: |
| WillBlockEntered(); |
| break; |
| } |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::BlockingTypeUpgraded() { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| DCHECK(worker_only().is_running_task); |
| |
| // The blocking type always being WILL_BLOCK in this experiment, it should |
| // never be considered "upgraded". |
| if (outer_->after_start().may_block_without_delay) |
| return; |
| |
| { |
| CheckedAutoLock auto_lock(outer_->lock_); |
| |
| // Don't do anything if a MAY_BLOCK ScopedBlockingCall instantiated in the |
| // same scope already caused the max tasks to be incremented. |
| if (incremented_max_tasks_since_blocked_) |
| return; |
| |
| // Cancel the effect of a MAY_BLOCK ScopedBlockingCall instantiated in the |
| // same scope. |
| if (!read_worker().may_block_start_time.is_null()) { |
| write_worker().may_block_start_time = TimeTicks(); |
| --outer_->num_unresolved_may_block_; |
| if (*read_worker().current_task_priority == TaskPriority::BEST_EFFORT) |
| --outer_->num_unresolved_best_effort_may_block_; |
| } |
| } |
| |
| WillBlockEntered(); |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::BlockingEnded() { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| DCHECK(worker_only().is_running_task); |
| |
| CheckedAutoLock auto_lock(outer_->lock_); |
| if (incremented_max_tasks_since_blocked_) { |
| outer_->DecrementMaxTasksLockRequired(*read_worker().current_task_priority); |
| } else { |
| DCHECK(!read_worker().may_block_start_time.is_null()); |
| --outer_->num_unresolved_may_block_; |
| if (*read_worker().current_task_priority == TaskPriority::BEST_EFFORT) |
| --outer_->num_unresolved_best_effort_may_block_; |
| } |
| |
| incremented_max_tasks_since_blocked_ = false; |
| write_worker().may_block_start_time = TimeTicks(); |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::MayBlockEntered() { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| DCHECK(worker_only().is_running_task); |
| |
| ScopedWorkersExecutor executor(outer_.get()); |
| CheckedAutoLock auto_lock(outer_->lock_); |
| |
| DCHECK(!incremented_max_tasks_since_blocked_); |
| DCHECK(read_worker().may_block_start_time.is_null()); |
| write_worker().may_block_start_time = subtle::TimeTicksNowIgnoringOverride(); |
| ++outer_->num_unresolved_may_block_; |
| if (*read_worker().current_task_priority == TaskPriority::BEST_EFFORT) |
| ++outer_->num_unresolved_best_effort_may_block_; |
| |
| outer_->MaybeScheduleAdjustMaxTasksLockRequired(&executor); |
| } |
| |
| void ThreadGroupImpl::WorkerThreadDelegateImpl::WillBlockEntered() { |
| DCHECK_CALLED_ON_VALID_THREAD(worker_thread_checker_); |
| DCHECK(worker_only().is_running_task); |
| |
| ScopedWorkersExecutor executor(outer_.get()); |
| CheckedAutoLock auto_lock(outer_->lock_); |
| |
| DCHECK(!incremented_max_tasks_since_blocked_); |
| DCHECK(read_worker().may_block_start_time.is_null()); |
| incremented_max_tasks_since_blocked_ = true; |
| outer_->IncrementMaxTasksLockRequired(*read_worker().current_task_priority); |
| outer_->EnsureEnoughWorkersLockRequired(&executor); |
| } |
| |
| bool ThreadGroupImpl::WorkerThreadDelegateImpl::CanGetWorkLockRequired( |
| WorkerThread* worker) { |
| // To avoid searching through the idle stack : use GetLastUsedTime() not being |
| // null (or being directly on top of the idle stack) as a proxy for being on |
| // the idle stack. |
| const bool is_on_idle_workers_stack = |
| outer_->idle_workers_stack_.Peek() == worker || |
| !worker->GetLastUsedTime().is_null(); |
| DCHECK_EQ(is_on_idle_workers_stack, |
| outer_->idle_workers_stack_.Contains(worker)); |
| |
| if (is_on_idle_workers_stack) { |
| if (CanCleanupLockRequired(worker)) |
| CleanupLockRequired(worker); |
| return false; |
| } |
| |
| // Excess workers should not get work, until they are no longer excess (i.e. |
| // max tasks increases). This ensures that if we have excess workers in the |
| // thread group, they get a chance to no longer be excess before being cleaned |
| // up. |
| if (outer_->GetNumAwakeWorkersLockRequired() > |
| outer_->GetDesiredNumAwakeWorkersLockRequired()) { |
| OnWorkerBecomesIdleLockRequired(worker); |
| return false; |
| } |
| |
| return true; |
| } |
| |
| bool ThreadGroupImpl::WorkerThreadDelegateImpl:: |
| MustIncrementMaxTasksLockRequired() { |
| if (!incremented_max_tasks_since_blocked_ && |
| !read_any().may_block_start_time.is_null() && |
| subtle::TimeTicksNowIgnoringOverride() - |
| read_any().may_block_start_time >= |
| outer_->after_start().may_block_threshold) { |
| incremented_max_tasks_since_blocked_ = true; |
| |
| --outer_->num_unresolved_may_block_; |
| if (*read_any().current_task_priority == TaskPriority::BEST_EFFORT) |
| --outer_->num_unresolved_best_effort_may_block_; |
| |
| return true; |
| } |
| |
| return false; |
| } |
| |
| void ThreadGroupImpl::WaitForWorkersIdleLockRequiredForTesting(size_t n) { |
| // Make sure workers do not cleanup while watching the idle count. |
| AutoReset<bool> ban_cleanups(&worker_cleanup_disallowed_for_testing_, true); |
| |
| while (idle_workers_stack_.Size() < n) |
| idle_workers_stack_cv_for_testing_->Wait(); |
| } |
| |
| void ThreadGroupImpl::MaintainAtLeastOneIdleWorkerLockRequired( |
| ScopedWorkersExecutor* executor) { |
| if (workers_.size() == kMaxNumberOfWorkers) |
| return; |
| DCHECK_LT(workers_.size(), kMaxNumberOfWorkers); |
| |
| if (!idle_workers_stack_.IsEmpty()) |
| return; |
| |
| if (workers_.size() >= max_tasks_) |
| return; |
| |
| scoped_refptr<WorkerThread> new_worker = |
| CreateAndRegisterWorkerLockRequired(executor); |
| DCHECK(new_worker); |
| idle_workers_stack_.Push(new_worker.get()); |
| } |
| |
| scoped_refptr<WorkerThread> |
| ThreadGroupImpl::CreateAndRegisterWorkerLockRequired( |
| ScopedWorkersExecutor* executor) { |
| DCHECK_LT(workers_.size(), max_tasks_); |
| DCHECK_LT(workers_.size(), kMaxNumberOfWorkers); |
| DCHECK(idle_workers_stack_.IsEmpty()); |
| |
| // WorkerThread needs |lock_| as a predecessor for its thread lock |
| // because in WakeUpOneWorker, |lock_| is first acquired and then |
| // the thread lock is acquired when WakeUp is called on the worker. |
| scoped_refptr<WorkerThread> worker = |
| MakeRefCounted<WorkerThread>(priority_hint_, |
| std::make_unique<WorkerThreadDelegateImpl>( |
| tracked_ref_factory_.GetTrackedRef()), |
| task_tracker_, &lock_); |
| |
| workers_.push_back(worker); |
| executor->ScheduleStart(worker); |
| DCHECK_LE(workers_.size(), max_tasks_); |
| |
| if (!cleanup_timestamps_.empty()) { |
| detach_duration_histogram_->AddTime(subtle::TimeTicksNowIgnoringOverride() - |
| cleanup_timestamps_.top()); |
| cleanup_timestamps_.pop(); |
| } |
| |
| return worker; |
| } |
| |
| size_t ThreadGroupImpl::GetNumAwakeWorkersLockRequired() const { |
| DCHECK_GE(workers_.size(), idle_workers_stack_.Size()); |
| size_t num_awake_workers = workers_.size() - idle_workers_stack_.Size(); |
| DCHECK_GE(num_awake_workers, num_running_tasks_); |
| return num_awake_workers; |
| } |
| |
| size_t ThreadGroupImpl::GetDesiredNumAwakeWorkersLockRequired() const { |
| // Number of BEST_EFFORT task sources that are running or queued and allowed |
| // to run by the CanRunPolicy. |
| const size_t num_running_or_queued_can_run_best_effort_task_sources = |
| num_running_best_effort_tasks_ + |
| GetNumAdditionalWorkersForBestEffortTaskSourcesLockRequired(); |
| |
| const size_t workers_for_best_effort_task_sources = |
| std::max(std::min(num_running_or_queued_can_run_best_effort_task_sources, |
| max_best_effort_tasks_), |
| num_running_best_effort_tasks_); |
| |
| // Number of USER_{VISIBLE|BLOCKING} task sources that are running or queued. |
| const size_t num_running_or_queued_foreground_task_sources = |
| (num_running_tasks_ - num_running_best_effort_tasks_) + |
| GetNumAdditionalWorkersForForegroundTaskSourcesLockRequired(); |
| |
| const size_t workers_for_foreground_task_sources = |
| num_running_or_queued_foreground_task_sources; |
| |
| return std::min({workers_for_best_effort_task_sources + |
| workers_for_foreground_task_sources, |
| max_tasks_, kMaxNumberOfWorkers}); |
| } |
| |
| void ThreadGroupImpl::DidUpdateCanRunPolicy() { |
| ScopedWorkersExecutor executor(this); |
| CheckedAutoLock auto_lock(lock_); |
| EnsureEnoughWorkersLockRequired(&executor); |
| } |
| |
| void ThreadGroupImpl::EnsureEnoughWorkersLockRequired( |
| BaseScopedWorkersExecutor* base_executor) { |
| // Don't do anything if the thread group isn't started. |
| if (max_tasks_ == 0) |
| return; |
| |
| ScopedWorkersExecutor* executor = |
| static_cast<ScopedWorkersExecutor*>(base_executor); |
| |
| const size_t desired_num_awake_workers = |
| GetDesiredNumAwakeWorkersLockRequired(); |
| const size_t num_awake_workers = GetNumAwakeWorkersLockRequired(); |
| |
| size_t num_workers_to_wake_up = |
| ClampSub(desired_num_awake_workers, num_awake_workers); |
| num_workers_to_wake_up = std::min(num_workers_to_wake_up, size_t(2U)); |
| |
| // Wake up the appropriate number of workers. |
| for (size_t i = 0; i < num_workers_to_wake_up; ++i) { |
| MaintainAtLeastOneIdleWorkerLockRequired(executor); |
| WorkerThread* worker_to_wakeup = idle_workers_stack_.Pop(); |
| DCHECK(worker_to_wakeup); |
| executor->ScheduleWakeUp(worker_to_wakeup); |
| } |
| |
| // In the case where the loop above didn't wake up any worker and we don't |
| // have excess workers, the idle worker should be maintained. This happens |
| // when called from the last worker awake, or a recent increase in |max_tasks| |
| // now makes it possible to keep an idle worker. |
| if (desired_num_awake_workers == num_awake_workers) |
| MaintainAtLeastOneIdleWorkerLockRequired(executor); |
| |
| // This function is called every time a task source is (re-)enqueued, |
| // hence the minimum priority needs to be updated. |
| UpdateMinAllowedPriorityLockRequired(); |
| |
| // Ensure that the number of workers is periodically adjusted if needed. |
| MaybeScheduleAdjustMaxTasksLockRequired(executor); |
| } |
| |
| void ThreadGroupImpl::AdjustMaxTasks() { |
| DCHECK( |
| after_start().service_thread_task_runner->RunsTasksInCurrentSequence()); |
| |
| ScopedWorkersExecutor executor(this); |
| CheckedAutoLock auto_lock(lock_); |
| DCHECK(adjust_max_tasks_posted_); |
| adjust_max_tasks_posted_ = false; |
| |
| // Increment max tasks for each worker that has been within a MAY_BLOCK |
| // ScopedBlockingCall for more than may_block_threshold. |
| for (scoped_refptr<WorkerThread> worker : workers_) { |
| // The delegates of workers inside a ThreadGroupImpl should be |
| // WorkerThreadDelegateImpls. |
| WorkerThreadDelegateImpl* delegate = |
| static_cast<WorkerThreadDelegateImpl*>(worker->delegate()); |
| AnnotateAcquiredLockAlias annotate(lock_, delegate->lock()); |
| if (delegate->MustIncrementMaxTasksLockRequired()) { |
| IncrementMaxTasksLockRequired( |
| delegate->current_task_priority_lock_required()); |
| } |
| } |
| |
| // Wake up workers according to the updated |max_tasks_|. This will also |
| // reschedule AdjustMaxTasks() if necessary. |
| EnsureEnoughWorkersLockRequired(&executor); |
| } |
| |
| void ThreadGroupImpl::ScheduleAdjustMaxTasks() { |
| // |adjust_max_tasks_posted_| can't change before the task posted below runs. |
| // Skip check on NaCl to avoid unsafe reference acquisition warning. |
| #if !defined(OS_NACL) |
| DCHECK(TS_UNCHECKED_READ(adjust_max_tasks_posted_)); |
| #endif |
| |
| after_start().service_thread_task_runner->PostDelayedTask( |
| FROM_HERE, BindOnce(&ThreadGroupImpl::AdjustMaxTasks, Unretained(this)), |
| after_start().blocked_workers_poll_period); |
| } |
| |
| void ThreadGroupImpl::MaybeScheduleAdjustMaxTasksLockRequired( |
| ScopedWorkersExecutor* executor) { |
| if (!adjust_max_tasks_posted_ && |
| ShouldPeriodicallyAdjustMaxTasksLockRequired()) { |
| executor->ScheduleAdjustMaxTasks(); |
| adjust_max_tasks_posted_ = true; |
| } |
| } |
| |
| bool ThreadGroupImpl::ShouldPeriodicallyAdjustMaxTasksLockRequired() { |
| // AdjustMaxTasks() should be scheduled to periodically adjust |max_tasks_| |
| // and |max_best_effort_tasks_| when (1) the concurrency limits are not large |
| // enough to accommodate all queued and running task sources and an idle |
| // worker and (2) there are unresolved MAY_BLOCK ScopedBlockingCalls. |
| // - When (1) is false: No worker would be created or woken up if the |
| // concurrency limits were increased, so there is no hurry to increase them. |
| // - When (2) is false: The concurrency limits could not be increased by |
| // AdjustMaxTasks(). |
| |
| const size_t num_running_or_queued_best_effort_task_sources = |
| num_running_best_effort_tasks_ + |
| GetNumAdditionalWorkersForBestEffortTaskSourcesLockRequired(); |
| if (num_running_or_queued_best_effort_task_sources > max_best_effort_tasks_ && |
| num_unresolved_best_effort_may_block_ > 0) { |
| return true; |
| } |
| |
| const size_t num_running_or_queued_task_sources = |
| num_running_tasks_ + |
| GetNumAdditionalWorkersForBestEffortTaskSourcesLockRequired() + |
| GetNumAdditionalWorkersForForegroundTaskSourcesLockRequired(); |
| constexpr size_t kIdleWorker = 1; |
| return num_running_or_queued_task_sources + kIdleWorker > max_tasks_ && |
| num_unresolved_may_block_ > 0; |
| } |
| |
| void ThreadGroupImpl::UpdateMinAllowedPriorityLockRequired() { |
| if (priority_queue_.IsEmpty() || num_running_tasks_ < max_tasks_) { |
| min_allowed_priority_.store(TaskPriority::BEST_EFFORT, |
| std::memory_order_relaxed); |
| } else { |
| min_allowed_priority_.store(priority_queue_.PeekSortKey().priority(), |
| std::memory_order_relaxed); |
| } |
| } |
| |
| void ThreadGroupImpl::DecrementTasksRunningLockRequired(TaskPriority priority) { |
| DCHECK_GT(num_running_tasks_, 0U); |
| --num_running_tasks_; |
| if (priority == TaskPriority::BEST_EFFORT) { |
| DCHECK_GT(num_running_best_effort_tasks_, 0U); |
| --num_running_best_effort_tasks_; |
| } |
| UpdateMinAllowedPriorityLockRequired(); |
| } |
| |
| void ThreadGroupImpl::IncrementTasksRunningLockRequired(TaskPriority priority) { |
| ++num_running_tasks_; |
| DCHECK_LE(num_running_tasks_, max_tasks_); |
| DCHECK_LE(num_running_tasks_, kMaxNumberOfWorkers); |
| if (priority == TaskPriority::BEST_EFFORT) { |
| ++num_running_best_effort_tasks_; |
| DCHECK_LE(num_running_best_effort_tasks_, num_running_tasks_); |
| DCHECK_LE(num_running_best_effort_tasks_, max_best_effort_tasks_); |
| } |
| UpdateMinAllowedPriorityLockRequired(); |
| } |
| |
| void ThreadGroupImpl::DecrementMaxTasksLockRequired(TaskPriority priority) { |
| DCHECK_GT(num_running_tasks_, 0U); |
| DCHECK_GT(max_tasks_, 0U); |
| --max_tasks_; |
| if (priority == TaskPriority::BEST_EFFORT) |
| --max_best_effort_tasks_; |
| UpdateMinAllowedPriorityLockRequired(); |
| } |
| |
| void ThreadGroupImpl::IncrementMaxTasksLockRequired(TaskPriority priority) { |
| DCHECK_GT(num_running_tasks_, 0U); |
| ++max_tasks_; |
| if (priority == TaskPriority::BEST_EFFORT) |
| ++max_best_effort_tasks_; |
| UpdateMinAllowedPriorityLockRequired(); |
| } |
| |
| ThreadGroupImpl::InitializedInStart::InitializedInStart() = default; |
| ThreadGroupImpl::InitializedInStart::~InitializedInStart() = default; |
| |
| } // namespace internal |
| } // namespace base |