Files
tubestation/xpcom/threads/TaskController.cpp
Jens Stutte 00d84f5344 Bug 1903758 - Make mozjemalloc have a lazy purge for all arenas via idle processing on the main thread. r=smaug
We can defer the purging of arenas to happen during idle processing on the main thread.

We already have the following prerequisites thanks to bug 1488780:

- The (often) expensive OS functions to give back memory pages are not blocking the use of the arena on other threads anymore.

- A single call to moz_may_purge_one_now (D232083) wraps just arena_t::Purge() that will just do "some work on one chunk" and tell if more is needed, giving us a fine grained control.

Synchronous purging can block the caller of a memory freeing function for an unexpectedly long time. Furthermore, memory that might be reclaimed very soon can be madvised early and thus its reuse can lead to frequent page faults.

We thus use moz_enable_deferred_purge (see D232083) to queue purge requests and execute them on the main thread only if it is about to become idle. We do this using an IdleTaskRunner that ensures we won't purge too often or never.

We believe that the main thread being idle is probably the best easy indicator we have to tell if the process is idle enough to purge without performance regrets.

We expect the peak memory usage of a single arena to not be affected significantly by this during normal use, but the time that this peak holds up might extend. This means the peak sum of all memory from all running processes may rise for short periods of time until enough purges happened on potentially several processes.

There is a chance to mitigate this effect by lowering the settings of allowed dirty pages for arenas, as there should be less churn in general with this patch, potentially resulting in a lower memory usage in average.

Differential Revision: https://phabricator.services.mozilla.com/D220616
2025-01-17 16:13:33 +00:00

1338 lines
44 KiB
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "TaskController.h"
#include "IdleTaskRunner.h"
#include "nsIIdleRunnable.h"
#include "nsIRunnable.h"
#include "nsThreadUtils.h"
#include <algorithm>
#include "GeckoProfiler.h"
#include "mozilla/AppShutdown.h"
#include "mozilla/BackgroundHangMonitor.h"
#include "mozilla/EventQueue.h"
#include "mozilla/Hal.h"
#include "mozilla/InputTaskManager.h"
#include "mozilla/VsyncTaskManager.h"
#include "mozilla/IOInterposer.h"
#include "mozilla/Perfetto.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/SchedulerGroup.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/FlowMarkers.h"
#include "mozilla/StaticPrefs_memory.h"
#include "nsIThreadInternal.h"
#include "nsThread.h"
#include "prenv.h"
#include "prsystem.h"
namespace mozilla {
StaticAutoPtr<TaskController> TaskController::sSingleton;
std::atomic<uint64_t> Task::sCurrentTaskSeqNo = 0;
const int32_t kMinimumPoolThreadCount = 2;
const int32_t kMaximumPoolThreadCount = 8;
// We want our default stack size limit to be approximately 2MB, to be safe for
// JS helper tasks that can use a lot of stack, but expect most threads to use
// much less. On Linux, however, requesting a stack of 2MB or larger risks the
// kernel allocating an entire 2MB huge page for it on first access, which we do
// not want. To avoid this possibility, we subtract 2 standard VM page sizes
// from our default.
constexpr uint32_t kBaseStackSize = 2048 * 1024 - 2 * 4096;
// TSan enforces a minimum stack size that's just slightly larger than our
// default helper stack size. It does this to store blobs of TSan-specific data
// on each thread's stack. Unfortunately, that means that even though we'll
// actually receive a larger stack than we requested, the effective usable space
// of that stack is significantly less than what we expect. To offset TSan
// stealing our stack space from underneath us, double the default.
//
// Similarly, ASan requires more stack space due to red-zones.
#if defined(MOZ_TSAN) || defined(MOZ_ASAN)
constexpr uint32_t kStackSize = 2 * kBaseStackSize;
#else
constexpr uint32_t kStackSize = kBaseStackSize;
#endif
struct PoolThread {
const size_t mIndex;
PRThread* mThread = nullptr;
CondVar mThreadCV;
RefPtr<Task> mCurrentTask;
// This may be higher than mCurrentTask's priority due to priority
// propagation. This is -only- valid when mCurrentTask != nullptr.
uint32_t mEffectiveTaskPriority = 0;
PoolThread(size_t aIndex, Mutex& aGraphMutex)
: mIndex(aIndex), mThreadCV(aGraphMutex, "PoolThread::mThreadCV") {}
};
/* static */
int32_t TaskController::GetPoolThreadCount() {
if (PR_GetEnv("MOZ_TASKCONTROLLER_THREADCOUNT")) {
return strtol(PR_GetEnv("MOZ_TASKCONTROLLER_THREADCOUNT"), nullptr, 0);
}
int32_t numCores = 0;
#if defined(XP_MACOSX) && defined(__aarch64__)
if (const auto& cpuInfo = hal::GetHeterogeneousCpuInfo()) {
// -1 because of the main thread.
numCores = cpuInfo->mBigCpus.Count() + cpuInfo->mMediumCpus.Count() - 1;
} else
#endif
{
numCores = std::max<int32_t>(1, PR_GetNumberOfProcessors());
}
return std::clamp<int32_t>(numCores, kMinimumPoolThreadCount,
kMaximumPoolThreadCount);
}
#if defined(MOZ_COLLECTING_RUNNABLE_TELEMETRY)
// This struct is duplicated below as 'IncompleteTaskMarker'.
// Make sure you keep the two in sync.
// The only difference between the two schemas is the type of the "task" field:
// TaskMarker uses TerminatingFlow and IncompleteTaskMarker uses Flow.
// We have two schemas so that we don't need to emit a separate marker for the
// TerminatingFlow in the common case.
struct TaskMarker : BaseMarkerType<TaskMarker> {
static constexpr const char* Name = "Task";
static constexpr const char* Description =
"Marker representing a task being executed in TaskController.";
using MS = MarkerSchema;
static constexpr MS::PayloadField PayloadFields[] = {
{"name", MS::InputType::CString, "Task Name", MS::Format::String,
MS::PayloadFlags::Searchable},
{"priority", MS::InputType::Uint32, "Priority level",
MS::Format::Integer},
{"task", MS::InputType::Uint64, "Task", MS::Format::TerminatingFlow,
MS::PayloadFlags::Searchable},
{"priorityName", MS::InputType::CString, "Priority Name"}};
static constexpr MS::Location Locations[] = {MS::Location::MarkerChart,
MS::Location::MarkerTable};
static constexpr const char* ChartLabel = "{marker.data.name}";
static constexpr const char* TableLabel =
"{marker.name} - {marker.data.name} - priority: "
"{marker.data.priorityName} ({marker.data.priority})"
" task: {marker.data.task}";
static constexpr bool IsStackBased = true;
static constexpr MS::ETWMarkerGroup Group = MS::ETWMarkerGroup::Scheduling;
static void TranslateMarkerInputToSchema(void* aContext,
const nsCString& aName,
uint32_t aPriority, Flow aFlow) {
ETW::OutputMarkerSchema(aContext, TaskMarker{}, aName, aPriority, aFlow,
ProfilerStringView(""));
}
static void StreamJSONMarkerData(baseprofiler::SpliceableJSONWriter& aWriter,
const nsCString& aName, uint32_t aPriority,
Flow aFlow) {
aWriter.StringProperty("name", aName);
aWriter.IntProperty("priority", aPriority);
# define EVENT_PRIORITY(NAME, VALUE) \
if (aPriority == (VALUE)) { \
aWriter.StringProperty("priorityName", #NAME); \
} else
EVENT_QUEUE_PRIORITY_LIST(EVENT_PRIORITY)
# undef EVENT_PRIORITY
{
aWriter.StringProperty("priorityName", "Invalid Value");
}
aWriter.FlowProperty("task", aFlow);
}
};
// This is a duplicate of the code above with the format of the 'task'
// field changed from `TerminatingFlow` to Flow`
struct IncompleteTaskMarker : BaseMarkerType<IncompleteTaskMarker> {
static constexpr const char* Name = "Task";
static constexpr const char* Description =
"Marker representing a task being executed in TaskController.";
using MS = MarkerSchema;
static constexpr MS::PayloadField PayloadFields[] = {
{"name", MS::InputType::CString, "Task Name", MS::Format::String,
MS::PayloadFlags::Searchable},
{"priority", MS::InputType::Uint32, "Priority level",
MS::Format::Integer},
{"task", MS::InputType::Uint64, "Task", MS::Format::Flow,
MS::PayloadFlags::Searchable},
{"priorityName", MS::InputType::CString, "Priority Name"}};
static constexpr MS::Location Locations[] = {MS::Location::MarkerChart,
MS::Location::MarkerTable};
static constexpr const char* ChartLabel = "{marker.data.name}";
static constexpr const char* TableLabel =
"{marker.name} - {marker.data.name} - priority: "
"{marker.data.priorityName} ({marker.data.priority})"
" task: {marker.data.task}";
static constexpr bool IsStackBased = true;
static constexpr MS::ETWMarkerGroup Group = MS::ETWMarkerGroup::Scheduling;
static void TranslateMarkerInputToSchema(void* aContext,
const nsCString& aName,
uint32_t aPriority, Flow aFlow) {
ETW::OutputMarkerSchema(aContext, IncompleteTaskMarker{}, aName, aPriority,
aFlow, ProfilerStringView(""));
}
static void StreamJSONMarkerData(baseprofiler::SpliceableJSONWriter& aWriter,
const nsCString& aName, uint32_t aPriority,
Flow aFlow) {
aWriter.StringProperty("name", aName);
aWriter.IntProperty("priority", aPriority);
# define EVENT_PRIORITY(NAME, VALUE) \
if (aPriority == (VALUE)) { \
aWriter.StringProperty("priorityName", #NAME); \
} else
EVENT_QUEUE_PRIORITY_LIST(EVENT_PRIORITY)
# undef EVENT_PRIORITY
{
aWriter.StringProperty("priorityName", "Invalid Value");
}
aWriter.FlowProperty("task", aFlow);
}
};
// Wrap task->Run() so that we can add markers for it
Task::TaskResult TaskController::RunTask(Task* aTask) {
if (!profiler_is_collecting_markers()) {
return aTask->Run();
}
TimeStamp startTime = TimeStamp::Now();
nsAutoCString name;
aTask->GetName(name);
PERFETTO_TRACE_EVENT("task", perfetto::DynamicString{name.get()});
AUTO_PROFILER_LABEL_DYNAMIC_NSCSTRING_NONSENSITIVE("Task", OTHER, name);
auto result = aTask->Run();
if (profiler_thread_is_being_profiled_for_markers()) {
AUTO_PROFILER_LABEL("AutoProfileTask", PROFILER);
AUTO_PROFILER_STATS(AUTO_PROFILE_TASK);
auto priority = aTask->GetPriority();
auto flow = Flow::FromPointer(aTask);
if (result == Task::TaskResult::Complete) {
profiler_add_marker("Runnable", baseprofiler::category::OTHER,
MarkerTiming::IntervalUntilNowFrom(startTime),
TaskMarker{}, name, priority, flow);
} else {
profiler_add_marker("Runnable", baseprofiler::category::OTHER,
MarkerTiming::IntervalUntilNowFrom(startTime),
IncompleteTaskMarker{}, name, priority, flow);
}
}
return result;
}
#else
Task::TaskResult TaskController::RunTask(Task* aTask) { return aTask->Run(); }
#endif
bool TaskManager::
UpdateCachesForCurrentIterationAndReportPriorityModifierChanged(
const MutexAutoLock& aProofOfLock, IterationType aIterationType) {
mCurrentSuspended = IsSuspended(aProofOfLock);
if (aIterationType == IterationType::EVENT_LOOP_TURN && !mCurrentSuspended) {
int32_t oldModifier = mCurrentPriorityModifier;
mCurrentPriorityModifier =
GetPriorityModifierForEventLoopTurn(aProofOfLock);
if (mCurrentPriorityModifier != oldModifier) {
return true;
}
}
return false;
}
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
class MOZ_RAII AutoSetMainThreadRunnableName {
public:
explicit AutoSetMainThreadRunnableName(const nsCString& aName) {
MOZ_ASSERT(NS_IsMainThread());
// We want to record our current runnable's name in a static so
// that BHR can record it.
mRestoreRunnableName = nsThread::sMainThreadRunnableName;
// Copy the name into sMainThreadRunnableName's buffer, and append a
// terminating null.
uint32_t length = std::min((uint32_t)nsThread::kRunnableNameBufSize - 1,
(uint32_t)aName.Length());
memcpy(nsThread::sMainThreadRunnableName.begin(), aName.BeginReading(),
length);
nsThread::sMainThreadRunnableName[length] = '\0';
}
~AutoSetMainThreadRunnableName() {
nsThread::sMainThreadRunnableName = mRestoreRunnableName;
}
private:
Array<char, nsThread::kRunnableNameBufSize> mRestoreRunnableName;
};
#endif
Task* Task::GetHighestPriorityDependency() {
Task* currentTask = this;
while (!currentTask->mDependencies.empty()) {
auto iter = currentTask->mDependencies.begin();
while (iter != currentTask->mDependencies.end()) {
if ((*iter)->mCompleted) {
auto oldIter = iter;
iter++;
// Completed tasks are removed here to prevent needlessly keeping them
// alive or iterating over them in the future.
currentTask->mDependencies.erase(oldIter);
continue;
}
currentTask = iter->get();
break;
}
}
return currentTask == this ? nullptr : currentTask;
}
#ifdef MOZ_MEMORY
static StaticRefPtr<IdleTaskRunner> sIdleMemoryCleanupRunner;
static const char kEnableLazyPurgePref[] = "memory.lazypurge.enable";
static const char kMaxPurgeDelayPref[] = "memory.lazypurge.maximum_delay";
static const char kMinPurgeBudgetPref[] =
"memory.lazypurge.minimum_idle_budget";
#endif
void TaskController::Initialize() {
MOZ_ASSERT(!sSingleton);
sSingleton = new TaskController();
}
void ThreadFuncPoolThread(void* aData) {
auto* thread = static_cast<PoolThread*>(aData);
TaskController::Get()->RunPoolThread(thread);
}
TaskController::TaskController()
: mGraphMutex("TaskController::mGraphMutex"),
mMainThreadCV(mGraphMutex, "TaskController::mMainThreadCV"),
#ifdef MOZ_MEMORY
mIsLazyPurgeEnabled(false),
#endif
mRunOutOfMTTasksCounter(0) {
InputTaskManager::Init();
VsyncTaskManager::Init();
mMTProcessingRunnable = NS_NewRunnableFunction(
"TaskController::ExecutePendingMTTasks()",
[]() { TaskController::Get()->ProcessPendingMTTask(); });
mMTBlockingProcessingRunnable = NS_NewRunnableFunction(
"TaskController::ExecutePendingMTTasks()",
[]() { TaskController::Get()->ProcessPendingMTTask(true); });
}
void TaskController::InitializeThreadPool() {
mPoolInitializationMutex.AssertCurrentThreadOwns();
MOZ_ASSERT(!mThreadPoolInitialized);
mThreadPoolInitialized = true;
int32_t poolSize = GetPoolThreadCount();
for (int32_t i = 0; i < poolSize; i++) {
auto thread = MakeUnique<PoolThread>(i, mGraphMutex);
thread->mThread = PR_CreateThread(
PR_USER_THREAD, ThreadFuncPoolThread, thread.get(), PR_PRIORITY_NORMAL,
PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, kStackSize);
MOZ_RELEASE_ASSERT(thread->mThread,
"Failed to create TaskController pool thread");
mPoolThreads.emplace_back(std::move(thread));
}
mIdleThreadCount = mPoolThreads.size();
}
/* static */
size_t TaskController::GetThreadStackSize() { return kStackSize; }
void TaskController::SetPerformanceCounterState(
PerformanceCounterState* aPerformanceCounterState) {
mPerformanceCounterState = aPerformanceCounterState;
}
/* static */
void TaskController::Shutdown() {
InputTaskManager::Cleanup();
VsyncTaskManager::Cleanup();
if (sSingleton) {
sSingleton->ShutdownThreadPoolInternal();
sSingleton = nullptr;
}
MOZ_ASSERT(!sSingleton);
#ifdef MOZ_MEMORY
// We choose to not disable lazy purge on our shutdown as this might do a
// useless sync purge of all arenas during process shutdown.
// Note that we already stopped scheduling new idle purges after
// ShutdownPhase::AppShutdownConfirmed, so most likely it's already gone.
if (sIdleMemoryCleanupRunner) {
sIdleMemoryCleanupRunner->Cancel();
sIdleMemoryCleanupRunner = nullptr;
}
#endif
}
void TaskController::ShutdownThreadPoolInternal() {
{
// Prevent race condition on mShuttingDown and wait.
MutexAutoLock lock(mGraphMutex);
mShuttingDown = true;
for (auto& thread : mPoolThreads) {
thread->mThreadCV.NotifyAll();
}
}
for (auto& thread : mPoolThreads) {
PR_JoinThread(thread->mThread);
}
MOZ_ASSERT(mIdleThreadCount == mPoolThreads.size());
}
void TaskController::RunPoolThread(PoolThread* aThread) {
IOInterposer::RegisterCurrentThread();
nsAutoCString threadName;
threadName.AppendLiteral("TaskController #");
threadName.AppendInt(static_cast<int64_t>(aThread->mIndex));
AUTO_PROFILER_REGISTER_THREAD(threadName.get());
MutexAutoLock lock(mGraphMutex);
while (!mShuttingDown) {
if (!aThread->mCurrentTask) {
AUTO_PROFILER_LABEL("TaskController::RunPoolThread", IDLE);
aThread->mThreadCV.Wait();
continue;
}
Task* task = aThread->mCurrentTask;
bool taskCompleted = false;
{
MutexAutoUnlock unlock(mGraphMutex);
taskCompleted = RunTask(task) == Task::TaskResult::Complete;
}
task->mInProgress = false;
if (!taskCompleted) {
// Presumably this task was interrupted, leave its dependencies
// unresolved and reinsert into the queue.
auto insertion = mThreadableTasks.insert(aThread->mCurrentTask);
MOZ_ASSERT(insertion.second);
task->mIterator = insertion.first;
} else {
task->mCompleted = true;
#ifdef DEBUG
task->mIsInGraph = false;
#endif
task->mDependencies.clear();
// This may have unblocked a main thread task. We could do this only
// if there was a main thread task before this one in the dependency
// chain.
mMayHaveMainThreadTask = true;
// Since this could have multiple dependencies thare are restricted
// to the main thread. Let's make sure that's awake.
EnsureMainThreadTasksScheduled();
MaybeInterruptTask(GetHighestPriorityMTTask(), lock);
}
// Clear the current task to mark ourselves idle.
RefPtr<Task> lastTask = aThread->mCurrentTask.forget();
mIdleThreadCount++;
MOZ_ASSERT(mIdleThreadCount <= mPoolThreads.size());
// Dispatch any other tasks that depended on this one.
DispatchThreadableTasks(lock);
// Ensure the last task is released before we enter the wait state. This
// happens outside the lock. This is required since it's perfectly feasible
// for task destructors to post events themselves.
{
MutexAutoUnlock unlock(mGraphMutex);
lastTask = nullptr;
}
}
MOZ_ASSERT(mThreadableTasks.empty());
IOInterposer::UnregisterCurrentThread();
}
void TaskController::AddTask(already_AddRefed<Task>&& aTask) {
RefPtr<Task> task(aTask);
if (task->GetKind() == Task::Kind::OffMainThreadOnly) {
MutexAutoLock lock(mPoolInitializationMutex);
if (!mThreadPoolInitialized) {
InitializeThreadPool();
}
}
MutexAutoLock lock(mGraphMutex);
if (TaskManager* manager = task->GetManager()) {
if (manager->mTaskCount == 0) {
mTaskManagers.insert(manager);
}
manager->DidQueueTask();
// Set this here since if this manager's priority modifier doesn't change
// we will not reprioritize when iterating over the queue.
task->mPriorityModifier = manager->mCurrentPriorityModifier;
}
if (profiler_is_active_and_unpaused()) {
task->mInsertionTime = TimeStamp::Now();
}
#ifdef DEBUG
task->mIsInGraph = true;
for (const RefPtr<Task>& otherTask : task->mDependencies) {
MOZ_ASSERT(!otherTask->mTaskManager ||
otherTask->mTaskManager == task->mTaskManager);
}
#endif
LogTask::LogDispatch(task);
profiler_add_marker("TaskController::AddTask", baseprofiler::category::OTHER,
MarkerTiming::InstantNow(), FlowMarker{},
Flow::FromPointer(task.get()));
std::pair<std::set<RefPtr<Task>, Task::PriorityCompare>::iterator, bool>
insertion;
switch (task->GetKind()) {
case Task::Kind::MainThreadOnly:
if (task->GetPriority() >=
static_cast<uint32_t>(EventQueuePriority::Normal) &&
!mMainThreadTasks.empty()) {
insertion = std::pair(
mMainThreadTasks.insert(--mMainThreadTasks.end(), std::move(task)),
true);
} else {
insertion = mMainThreadTasks.insert(std::move(task));
}
break;
case Task::Kind::OffMainThreadOnly:
insertion = mThreadableTasks.insert(std::move(task));
break;
}
(*insertion.first)->mIterator = insertion.first;
MOZ_ASSERT(insertion.second);
MaybeInterruptTask(*insertion.first, lock);
}
void TaskController::DispatchThreadableTasks(
const MutexAutoLock& aProofOfLock) {
while (MaybeDispatchOneThreadableTask(aProofOfLock)) {
// Loop.
}
}
bool TaskController::MaybeDispatchOneThreadableTask(
const MutexAutoLock& aProofOfLock) {
if (mThreadableTasks.empty() || mIdleThreadCount == 0) {
return false;
}
auto [task, effetivePriority] = TakeThreadableTaskToRun(aProofOfLock);
if (!task) {
return false;
}
PoolThread* thread = SelectThread(aProofOfLock);
MOZ_ASSERT(!thread->mCurrentTask);
MOZ_ASSERT(mIdleThreadCount != 0);
thread->mCurrentTask = task;
thread->mEffectiveTaskPriority = effetivePriority;
thread->mThreadCV.Notify();
task->mInProgress = true;
mIdleThreadCount--;
return true;
}
TaskController::TaskToRun TaskController::TakeThreadableTaskToRun(
const MutexAutoLock& aProofOfLock) {
MOZ_ASSERT(!mThreadableTasks.empty());
// Search for the highest priority dependency of the highest priority task.
for (const RefPtr<Task>& rootTask : mThreadableTasks) {
MOZ_ASSERT(!rootTask->mTaskManager);
Task* task = rootTask;
while (Task* nextTask = task->GetHighestPriorityDependency()) {
task = nextTask;
}
if (task->GetKind() != Task::Kind::MainThreadOnly && !task->mInProgress) {
TaskToRun taskToRun{task, rootTask->GetPriority()};
mThreadableTasks.erase(task->mIterator);
task->mIterator = mThreadableTasks.end();
return taskToRun;
}
}
return TaskToRun();
}
PoolThread* TaskController::SelectThread(const MutexAutoLock& aProofOfLock) {
MOZ_ASSERT(mIdleThreadCount != 0);
// This just picks the first free thread.
for (auto& thread : mPoolThreads) {
if (!thread->mCurrentTask) {
return thread.get();
}
}
MOZ_CRASH("Couldn't find idle thread");
}
void TaskController::WaitForTaskOrMessage() {
MutexAutoLock lock(mGraphMutex);
while (!mMayHaveMainThreadTask) {
AUTO_PROFILER_LABEL("TaskController::WaitForTaskOrMessage", IDLE);
mMainThreadCV.Wait();
}
}
void TaskController::ExecuteNextTaskOnlyMainThread() {
MOZ_ASSERT(NS_IsMainThread());
MutexAutoLock lock(mGraphMutex);
ExecuteNextTaskOnlyMainThreadInternal(lock);
}
void TaskController::ProcessPendingMTTask(bool aMayWait) {
MOZ_ASSERT(NS_IsMainThread());
MutexAutoLock lock(mGraphMutex);
for (;;) {
// We only ever process one event here. However we may sometimes
// not actually process a real event because of suspended tasks.
// This loop allows us to wait until we've processed something
// in that scenario.
mMTTaskRunnableProcessedTask = ExecuteNextTaskOnlyMainThreadInternal(lock);
if (mMTTaskRunnableProcessedTask || !aMayWait) {
break;
}
#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
// Unlock before calling into the BackgroundHangMonitor API as it uses
// the timer API.
{
MutexAutoUnlock unlock(mGraphMutex);
BackgroundHangMonitor().NotifyWait();
}
#endif
{
// ProcessNextEvent will also have attempted to wait, however we may have
// given it a Runnable when all the tasks in our task graph were suspended
// but we weren't able to cheaply determine that.
AUTO_PROFILER_LABEL("TaskController::ProcessPendingMTTask", IDLE);
mMainThreadCV.Wait();
}
#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
{
MutexAutoUnlock unlock(mGraphMutex);
BackgroundHangMonitor().NotifyActivity();
}
#endif
}
if (mMayHaveMainThreadTask) {
EnsureMainThreadTasksScheduled();
}
}
void TaskController::ReprioritizeTask(Task* aTask, uint32_t aPriority) {
MutexAutoLock lock(mGraphMutex);
std::set<RefPtr<Task>, Task::PriorityCompare>* queue = &mMainThreadTasks;
if (aTask->GetKind() == Task::Kind::OffMainThreadOnly) {
queue = &mThreadableTasks;
}
MOZ_ASSERT(aTask->mIterator != queue->end());
queue->erase(aTask->mIterator);
aTask->mPriority = aPriority;
auto insertion = queue->insert(aTask);
MOZ_ASSERT(insertion.second);
aTask->mIterator = insertion.first;
MaybeInterruptTask(aTask, lock);
}
// Code supporting runnable compatibility.
// Task that wraps a runnable.
class RunnableTask : public Task {
public:
RunnableTask(already_AddRefed<nsIRunnable>&& aRunnable, int32_t aPriority,
Kind aKind)
: Task(aKind, aPriority), mRunnable(aRunnable) {}
virtual TaskResult Run() override {
mRunnable->Run();
mRunnable = nullptr;
return TaskResult::Complete;
}
void SetIdleDeadline(TimeStamp aDeadline) override {
nsCOMPtr<nsIIdleRunnable> idleRunnable = do_QueryInterface(mRunnable);
if (idleRunnable) {
idleRunnable->SetDeadline(aDeadline);
}
}
virtual bool GetName(nsACString& aName) override {
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
if (nsCOMPtr<nsINamed> named = do_QueryInterface(mRunnable)) {
MOZ_ALWAYS_TRUE(NS_SUCCEEDED(named->GetName(aName)));
} else {
aName.AssignLiteral("non-nsINamed runnable");
}
if (aName.IsEmpty()) {
aName.AssignLiteral("anonymous runnable");
}
return true;
#else
return false;
#endif
}
private:
RefPtr<nsIRunnable> mRunnable;
};
void TaskController::DispatchRunnable(already_AddRefed<nsIRunnable>&& aRunnable,
uint32_t aPriority,
TaskManager* aManager) {
RefPtr<RunnableTask> task = new RunnableTask(std::move(aRunnable), aPriority,
Task::Kind::MainThreadOnly);
task->SetManager(aManager);
TaskController::Get()->AddTask(task.forget());
}
nsIRunnable* TaskController::GetRunnableForMTTask(bool aReallyWait) {
MutexAutoLock lock(mGraphMutex);
while (mMainThreadTasks.empty()) {
if (!aReallyWait) {
return nullptr;
}
AUTO_PROFILER_LABEL("TaskController::GetRunnableForMTTask::Wait", IDLE);
mMainThreadCV.Wait();
}
return aReallyWait ? mMTBlockingProcessingRunnable : mMTProcessingRunnable;
}
bool TaskController::HasMainThreadPendingTasks() {
MOZ_ASSERT(NS_IsMainThread());
auto resetIdleState = MakeScopeExit([&idleManager = mIdleTaskManager] {
if (idleManager) {
idleManager->State().ClearCachedIdleDeadline();
}
});
for (bool considerIdle : {false, true}) {
if (considerIdle && !mIdleTaskManager) {
continue;
}
MutexAutoLock lock(mGraphMutex);
if (considerIdle) {
mIdleTaskManager->State().ForgetPendingTaskGuarantee();
// Temporarily unlock so we can peek our idle deadline.
// XXX We could do this _before_ we take the lock if the API would let us.
// We do want to do this before looking at mMainThreadTasks, in case
// someone adds one while we're unlocked.
{
MutexAutoUnlock unlock(mGraphMutex);
mIdleTaskManager->State().CachePeekedIdleDeadline(unlock);
}
}
// Return early if there's no tasks at all.
if (mMainThreadTasks.empty()) {
return false;
}
// We can cheaply count how many tasks are suspended.
uint64_t totalSuspended = 0;
for (TaskManager* manager : mTaskManagers) {
DebugOnly<bool> modifierChanged =
manager
->UpdateCachesForCurrentIterationAndReportPriorityModifierChanged(
lock, TaskManager::IterationType::NOT_EVENT_LOOP_TURN);
MOZ_ASSERT(!modifierChanged);
// The idle manager should be suspended unless we're doing the idle pass.
MOZ_ASSERT(manager != mIdleTaskManager || manager->mCurrentSuspended ||
considerIdle,
"Why are idle tasks not suspended here?");
if (manager->mCurrentSuspended) {
// XXX - If managers manage off-main-thread tasks this breaks! This
// scenario is explicitly not supported.
//
// This is only incremented inside the lock -or- decremented on the main
// thread so this is safe.
totalSuspended += manager->mTaskCount;
}
}
// This would break down if we have a non-suspended task depending on a
// suspended task. This is why for the moment we do not allow tasks
// to be dependent on tasks managed by another taskmanager.
if (mMainThreadTasks.size() > totalSuspended) {
// If mIdleTaskManager->mTaskCount is 0, we never updated the suspended
// state of mIdleTaskManager above, hence shouldn't even check it here.
// But in that case idle tasks are not contributing to our suspended task
// count anyway.
if (mIdleTaskManager && mIdleTaskManager->mTaskCount &&
!mIdleTaskManager->mCurrentSuspended) {
MOZ_ASSERT(considerIdle, "Why is mIdleTaskManager not suspended?");
// Check whether the idle tasks were really needed to make our "we have
// an unsuspended task" decision. If they were, we need to force-enable
// idle tasks until we run our next task.
if (mMainThreadTasks.size() - mIdleTaskManager->mTaskCount <=
totalSuspended) {
mIdleTaskManager->State().EnforcePendingTaskGuarantee();
}
}
return true;
}
}
return false;
}
uint64_t TaskController::PendingMainthreadTaskCountIncludingSuspended() {
MutexAutoLock lock(mGraphMutex);
return mMainThreadTasks.size();
}
#ifdef MOZ_MEMORY
void TaskController::UpdateIdleMemoryCleanupPrefs() {
mIsLazyPurgeEnabled = StaticPrefs::memory_lazypurge_enable();
moz_enable_deferred_purge(mIsLazyPurgeEnabled);
}
static void PrefChangeCallback(const char* aPrefName, void* aNull) {
MOZ_ASSERT((0 == strcmp(aPrefName, kEnableLazyPurgePref)) ||
(0 == strcmp(aPrefName, kMaxPurgeDelayPref)) ||
(0 == strcmp(aPrefName, kMinPurgeBudgetPref)));
TaskController::Get()->UpdateIdleMemoryCleanupPrefs();
}
// static
void TaskController::SetupIdleMemoryCleanup() {
Preferences::RegisterCallback(PrefChangeCallback, kEnableLazyPurgePref);
Preferences::RegisterCallback(PrefChangeCallback, kMaxPurgeDelayPref);
Preferences::RegisterCallback(PrefChangeCallback, kMinPurgeBudgetPref);
TaskController::Get()->UpdateIdleMemoryCleanupPrefs();
}
void TaskController::MayScheduleIdleMemoryCleanup() {
// We want to schedule an idle task only if we:
// - know to be about to become idle
// - are not shutting down
// - have not yet an active IdleTaskRunner
// - have something to cleanup
if (PendingMainthreadTaskCountIncludingSuspended() > 0) {
// This is a hot code path for the main thread, so please do not add
// logic here or before.
return;
}
if (!mIsLazyPurgeEnabled) {
return;
}
if (AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed)) {
if (sIdleMemoryCleanupRunner) {
sIdleMemoryCleanupRunner->Cancel();
sIdleMemoryCleanupRunner = nullptr;
}
return;
}
if (!moz_may_purge_one_now(/* aPeekOnly */ true)) {
// Currently we unqueue purge requests only if we run moz_may_purge_one_now
// with aPeekOnly==false and that happens in the below IdleTaskRunner which
// cancels itself when done (and all of this happens on the main thread
// without possible races) OR if something else causes a MayPurgeAll (like
// jemalloc_free_(excess)_dirty_pages or moz_set_max_dirty_page_modifier)
// which can happen anytime (and even from other threads).
if (sIdleMemoryCleanupRunner) {
sIdleMemoryCleanupRunner->Cancel();
sIdleMemoryCleanupRunner = nullptr;
}
return;
}
if (sIdleMemoryCleanupRunner) {
return;
}
// Only create a marker if we really do something.
PROFILER_MARKER_TEXT("MayScheduleIdleMemoryCleanup", OTHER, {},
"Schedule for immediate run."_ns);
TimeDuration maxPurgeDelay = TimeDuration::FromMilliseconds(
StaticPrefs::memory_lazypurge_maximum_delay());
TimeDuration minPurgeBudget = TimeDuration::FromMilliseconds(
StaticPrefs::memory_lazypurge_minimum_idle_budget());
sIdleMemoryCleanupRunner = IdleTaskRunner::Create(
[](TimeStamp aDeadline) {
bool pending = moz_may_purge_one_now(true);
if (pending) {
AUTO_PROFILER_MARKER_TEXT(
"DoIdleMemoryCleanup", OTHER, {},
"moz_may_purge_one_now until there is budget."_ns);
while (pending) {
pending = moz_may_purge_one_now(false);
if (!aDeadline.IsNull() && TimeStamp::Now() > aDeadline) {
break;
}
}
}
if (!pending && sIdleMemoryCleanupRunner) {
PROFILER_MARKER_TEXT("DoIdleMemoryCleanup", OTHER, {},
"Finished all cleanup."_ns);
sIdleMemoryCleanupRunner->Cancel();
sIdleMemoryCleanupRunner = nullptr;
}
// We never get here without attempting at least one purge call.
return true;
},
"TaskController::IdlePurgeRunner", TimeDuration::FromMilliseconds(0),
maxPurgeDelay, minPurgeBudget, true, nullptr, nullptr);
// We do not pass aMayStopProcessing, which would be the only legitimate
// reason to return nullptr (OOM would crash), so no fallback needed.
MOZ_ASSERT(sIdleMemoryCleanupRunner);
}
#endif
bool TaskController::ExecuteNextTaskOnlyMainThreadInternal(
const MutexAutoLock& aProofOfLock) MOZ_REQUIRES(mGraphMutex) {
MOZ_ASSERT(NS_IsMainThread());
mGraphMutex.AssertCurrentThreadOwns();
// Block to make it easier to jump to our cleanup.
bool taskRan = false;
do {
taskRan = DoExecuteNextTaskOnlyMainThreadInternal(aProofOfLock);
if (taskRan) {
if (mIdleTaskManager && mIdleTaskManager->mTaskCount &&
mIdleTaskManager->IsSuspended(aProofOfLock)) {
uint32_t activeTasks = mMainThreadTasks.size();
for (TaskManager* manager : mTaskManagers) {
if (manager->IsSuspended(aProofOfLock)) {
activeTasks -= manager->mTaskCount;
} else {
break;
}
}
if (!activeTasks) {
// We have only idle (and maybe other suspended) tasks left, so need
// to update the idle state. We need to temporarily release the lock
// while we do that.
MutexAutoUnlock unlock(mGraphMutex);
mIdleTaskManager->State().RequestIdleDeadlineIfNeeded(unlock);
}
}
break;
}
if (!mIdleTaskManager) {
break;
}
if (mIdleTaskManager->mTaskCount) {
// We have idle tasks that we may not have gotten above because
// our idle state is not up to date. We need to update the idle state
// and try again. We need to temporarily release the lock while we do
// that.
MutexAutoUnlock unlock(mGraphMutex);
mIdleTaskManager->State().UpdateCachedIdleDeadline(unlock);
} else {
MutexAutoUnlock unlock(mGraphMutex);
mIdleTaskManager->State().RanOutOfTasks(unlock);
}
// When we unlocked, someone may have queued a new task on us. So try to
// see whether we can run things again.
taskRan = DoExecuteNextTaskOnlyMainThreadInternal(aProofOfLock);
} while (false);
if (mIdleTaskManager) {
// The pending task guarantee is not needed anymore, since we just tried
// running a task
mIdleTaskManager->State().ForgetPendingTaskGuarantee();
if (mMainThreadTasks.empty()) {
++mRunOutOfMTTasksCounter;
// XXX the IdlePeriodState API demands we have a MutexAutoUnlock for it.
// Otherwise we could perhaps just do this after we exit the locked block,
// by pushing the lock down into this method. Though it's not clear that
// we could check mMainThreadTasks.size() once we unlock, and whether we
// could maybe substitute mMayHaveMainThreadTask for that check.
MutexAutoUnlock unlock(mGraphMutex);
mIdleTaskManager->State().RanOutOfTasks(unlock);
}
}
return taskRan;
}
bool TaskController::DoExecuteNextTaskOnlyMainThreadInternal(
const MutexAutoLock& aProofOfLock) MOZ_REQUIRES(mGraphMutex) {
mGraphMutex.AssertCurrentThreadOwns();
nsCOMPtr<nsIThread> mainIThread;
NS_GetMainThread(getter_AddRefs(mainIThread));
nsThread* mainThread = static_cast<nsThread*>(mainIThread.get());
if (mainThread) {
mainThread->SetRunningEventDelay(TimeDuration(), TimeStamp());
}
uint32_t totalSuspended = 0;
for (TaskManager* manager : mTaskManagers) {
bool modifierChanged =
manager
->UpdateCachesForCurrentIterationAndReportPriorityModifierChanged(
aProofOfLock, TaskManager::IterationType::EVENT_LOOP_TURN);
if (modifierChanged) {
ProcessUpdatedPriorityModifier(manager);
}
if (manager->mCurrentSuspended) {
totalSuspended += manager->mTaskCount;
}
}
MOZ_ASSERT(mMainThreadTasks.size() >= totalSuspended);
// This would break down if we have a non-suspended task depending on a
// suspended task. This is why for the moment we do not allow tasks
// to be dependent on tasks managed by another taskmanager.
if (mMainThreadTasks.size() > totalSuspended) {
for (auto iter = mMainThreadTasks.begin(); iter != mMainThreadTasks.end();
iter++) {
Task* task = iter->get();
if (task->mTaskManager && task->mTaskManager->mCurrentSuspended) {
// Even though we may want to run some dependencies of this task, we
// will run them at their own priority level and not the priority
// level of their dependents.
continue;
}
task = GetFinalDependency(task);
if (task->GetKind() == Task::Kind::OffMainThreadOnly ||
task->mInProgress ||
(task->mTaskManager && task->mTaskManager->mCurrentSuspended)) {
continue;
}
mCurrentTasksMT.push(task);
mMainThreadTasks.erase(task->mIterator);
task->mIterator = mMainThreadTasks.end();
task->mInProgress = true;
TaskManager* manager = task->GetManager();
bool result = false;
{
MutexAutoUnlock unlock(mGraphMutex);
if (manager) {
manager->WillRunTask();
if (manager != mIdleTaskManager) {
// Notify the idle period state that we're running a non-idle task.
// This needs to happen while our mutex is not locked!
mIdleTaskManager->State().FlagNotIdle();
} else {
TimeStamp idleDeadline =
mIdleTaskManager->State().GetCachedIdleDeadline();
MOZ_ASSERT(
idleDeadline,
"How can we not have a deadline if our manager is enabled?");
task->SetIdleDeadline(idleDeadline);
}
}
if (mIdleTaskManager) {
// We found a task to run; we can clear the idle deadline on our idle
// task manager. This _must_ be done before we actually run the task,
// because running the task could reenter via spinning the event loop
// and we want to make sure there's no cached idle deadline at that
// point. But we have to make sure we do it after out SetIdleDeadline
// call above, in the case when the task is actually an idle task.
mIdleTaskManager->State().ClearCachedIdleDeadline();
}
TimeStamp now = TimeStamp::Now();
if (mainThread) {
if (task->GetPriority() < uint32_t(EventQueuePriority::InputHigh) ||
task->mInsertionTime.IsNull()) {
mainThread->SetRunningEventDelay(TimeDuration(), now);
} else {
mainThread->SetRunningEventDelay(now - task->mInsertionTime, now);
}
}
nsAutoCString name;
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
task->GetName(name);
#endif
PerformanceCounterState::Snapshot snapshot =
mPerformanceCounterState->RunnableWillRun(
now, manager == mIdleTaskManager);
{
LogTask::Run log(task);
#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
AutoSetMainThreadRunnableName nameGuard(name);
#endif
result = RunTask(task) == Task::TaskResult::Complete;
}
// Task itself should keep manager alive.
if (manager) {
manager->DidRunTask();
}
mPerformanceCounterState->RunnableDidRun(name, std::move(snapshot));
}
// Task itself should keep manager alive.
if (manager && result && manager->mTaskCount == 0) {
mTaskManagers.erase(manager);
}
task->mInProgress = false;
if (!result) {
// Presumably this task was interrupted, leave its dependencies
// unresolved and reinsert into the queue.
auto insertion =
mMainThreadTasks.insert(std::move(mCurrentTasksMT.top()));
MOZ_ASSERT(insertion.second);
task->mIterator = insertion.first;
if (manager) {
manager->WillRunTask();
}
} else {
task->mCompleted = true;
#ifdef DEBUG
task->mIsInGraph = false;
#endif
// Clear dependencies to release references.
task->mDependencies.clear();
// Dispatch any tasks that are now ready to run.
DispatchThreadableTasks(aProofOfLock);
}
mCurrentTasksMT.pop();
return true;
}
}
mMayHaveMainThreadTask = false;
if (mIdleTaskManager) {
// We did not find a task to run. We still need to clear the cached idle
// deadline on our idle state, because that deadline was only relevant to
// the execution of this function. Had we found a task, we would have
// cleared the deadline before running that task.
mIdleTaskManager->State().ClearCachedIdleDeadline();
}
return false;
}
Task* TaskController::GetFinalDependency(Task* aTask) {
Task* nextTask;
while ((nextTask = aTask->GetHighestPriorityDependency())) {
aTask = nextTask;
}
return aTask;
}
void TaskController::MaybeInterruptTask(Task* aTask,
const MutexAutoLock& aProofOfLock) {
mGraphMutex.AssertCurrentThreadOwns();
if (!aTask) {
return;
}
// This optimization prevents many slow lookups in long chains of similar
// priority.
if (!aTask->mDependencies.empty()) {
Task* firstDependency = aTask->mDependencies.begin()->get();
if (aTask->GetPriority() <= firstDependency->GetPriority() &&
!firstDependency->mCompleted &&
aTask->GetKind() == firstDependency->GetKind()) {
// This task has the same or a higher priority as one of its dependencies,
// never any need to interrupt.
return;
}
}
Task* finalDependency = GetFinalDependency(aTask);
if (finalDependency->mInProgress) {
// No need to wake anything, we can't schedule this task right now anyway.
return;
}
if (aTask->GetKind() == Task::Kind::MainThreadOnly) {
mMayHaveMainThreadTask = true;
EnsureMainThreadTasksScheduled();
if (mCurrentTasksMT.empty()) {
return;
}
// We could go through the steps above here and interrupt an off main
// thread task in case it has a lower priority.
if (finalDependency->GetKind() == Task::Kind::OffMainThreadOnly) {
return;
}
if (mCurrentTasksMT.top()->GetPriority() < aTask->GetPriority()) {
mCurrentTasksMT.top()->RequestInterrupt(aTask->GetPriority());
}
} else {
if (mIdleThreadCount != 0) {
DispatchThreadableTasks(aProofOfLock);
// There was a free thread, no need to interrupt anything.
return;
}
Task* lowestPriorityTask = nullptr;
for (auto& thread : mPoolThreads) {
MOZ_ASSERT(thread->mCurrentTask);
if (!lowestPriorityTask) {
lowestPriorityTask = thread->mCurrentTask.get();
continue;
}
// This should possibly select the lowest priority task which was started
// the latest. But for now we ignore that optimization.
// This also doesn't guarantee a task is interruptable, so that's an
// avenue for improvements as well.
if (lowestPriorityTask->GetPriority() > thread->mEffectiveTaskPriority) {
lowestPriorityTask = thread->mCurrentTask.get();
}
}
if (lowestPriorityTask->GetPriority() < aTask->GetPriority()) {
lowestPriorityTask->RequestInterrupt(aTask->GetPriority());
}
// We choose not to interrupt main thread tasks for tasks which may be
// executed off the main thread.
}
}
Task* TaskController::GetHighestPriorityMTTask() {
mGraphMutex.AssertCurrentThreadOwns();
if (!mMainThreadTasks.empty()) {
return mMainThreadTasks.begin()->get();
}
return nullptr;
}
void TaskController::EnsureMainThreadTasksScheduled() {
if (mObserver) {
mObserver->OnDispatchedEvent();
}
if (mExternalCondVar) {
mExternalCondVar->Notify();
}
mMainThreadCV.Notify();
}
void TaskController::ProcessUpdatedPriorityModifier(TaskManager* aManager) {
mGraphMutex.AssertCurrentThreadOwns();
MOZ_ASSERT(NS_IsMainThread());
int32_t modifier = aManager->mCurrentPriorityModifier;
std::vector<RefPtr<Task>> storedTasks;
// Find all relevant tasks.
for (auto iter = mMainThreadTasks.begin(); iter != mMainThreadTasks.end();) {
if ((*iter)->mTaskManager == aManager) {
storedTasks.push_back(*iter);
iter = mMainThreadTasks.erase(iter);
} else {
iter++;
}
}
// Reinsert found tasks with their new priorities.
for (RefPtr<Task>& ref : storedTasks) {
// Kept alive at first by the vector and then by mMainThreadTasks.
Task* task = ref;
task->mPriorityModifier = modifier;
auto insertion = mMainThreadTasks.insert(std::move(ref));
MOZ_ASSERT(insertion.second);
task->mIterator = insertion.first;
}
}
} // namespace mozilla