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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
#include "vm/InternalThreadPool.h"
#include "mozilla/TimeStamp.h"
#include "js/ProfilingCategory.h"
#include "js/ProfilingStack.h"
#include "threading/Thread.h"
#include "util/NativeStack.h"
#include "vm/HelperThreadState.h"
#include "vm/JSContext.h"
// We want our default stack size limit to be approximately 2MB, to be safe, 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.
static const uint32_t kDefaultHelperStackSize = 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.
//
// Note that we don't need this for ASan/MOZ_ASAN because ASan doesn't
// require all the thread-specific state that TSan does.
#if defined(MOZ_TSAN)
static const uint32_t HELPER_STACK_SIZE = 2 * kDefaultHelperStackSize;
#else
static const uint32_t HELPER_STACK_SIZE = kDefaultHelperStackSize;
#endif
// These macros are identical in function to the same-named ones in
// GeckoProfiler.h, but they are defined separately because SpiderMonkey can't
// use GeckoProfiler.h.
#define PROFILER_RAII_PASTE(id, line) id##line
#define PROFILER_RAII_EXPAND(id, line) PROFILER_RAII_PASTE(id, line)
#define PROFILER_RAII PROFILER_RAII_EXPAND(raiiObject, __LINE__)
#define AUTO_PROFILER_LABEL(label, categoryPair) \
HelperThread::AutoProfilerLabel PROFILER_RAII( \
this, label, JS::ProfilingCategoryPair::categoryPair)
using namespace js;
namespace js {
class HelperThread {
Thread thread;
/*
* The profiling thread for this helper thread, which can be used to push
* and pop label frames.
* This field being non-null indicates that this thread has been registered
* and needs to be unregistered at shutdown.
*/
ProfilingStack* profilingStack = nullptr;
public:
HelperThread();
[[nodiscard]] bool init(InternalThreadPool* pool);
ThreadId threadId() { return thread.get_id(); }
void join();
static void ThreadMain(InternalThreadPool* pool, HelperThread* helper);
void threadLoop(InternalThreadPool* pool);
void ensureRegisteredWithProfiler();
void unregisterWithProfilerIfNeeded();
private:
struct AutoProfilerLabel {
AutoProfilerLabel(HelperThread* helperThread, const char* label,
JS::ProfilingCategoryPair categoryPair);
~AutoProfilerLabel();
private:
ProfilingStack* profilingStack;
};
};
} // namespace js
InternalThreadPool* InternalThreadPool::Instance = nullptr;
/* static */ InternalThreadPool& InternalThreadPool::Get() {
MOZ_ASSERT(IsInitialized());
return *Instance;
}
/* static */
bool InternalThreadPool::Initialize(size_t threadCount,
AutoLockHelperThreadState& lock) {
if (IsInitialized()) {
return true;
}
auto instance = MakeUnique<InternalThreadPool>();
if (!instance) {
return false;
}
if (!instance->ensureThreadCount(threadCount, lock)) {
instance->shutDown(lock);
return false;
}
Instance = instance.release();
HelperThreadState().setDispatchTaskCallback(DispatchTask, threadCount,
HELPER_STACK_SIZE, lock);
return true;
}
bool InternalThreadPool::ensureThreadCount(size_t threadCount,
AutoLockHelperThreadState& lock) {
MOZ_ASSERT(threads(lock).length() < threadCount);
if (!threads(lock).reserve(threadCount)) {
return false;
}
while (threads(lock).length() < threadCount) {
auto thread = js::MakeUnique<HelperThread>();
if (!thread || !thread->init(this)) {
return false;
}
threads(lock).infallibleEmplaceBack(std::move(thread));
}
return true;
}
size_t InternalThreadPool::threadCount(const AutoLockHelperThreadState& lock) {
return threads(lock).length();
}
/* static */
void InternalThreadPool::ShutDown(AutoLockHelperThreadState& lock) {
MOZ_ASSERT(HelperThreadState().isTerminating(lock));
Get().shutDown(lock);
js_delete(Instance);
Instance = nullptr;
}
void InternalThreadPool::shutDown(AutoLockHelperThreadState& lock) {
MOZ_ASSERT(!terminating);
terminating = true;
notifyAll(lock);
for (auto& thread : threads(lock)) {
AutoUnlockHelperThreadState unlock(lock);
thread->join();
}
}
inline HelperThreadVector& InternalThreadPool::threads(
const AutoLockHelperThreadState& lock) {
return threads_.ref();
}
inline const HelperThreadVector& InternalThreadPool::threads(
const AutoLockHelperThreadState& lock) const {
return threads_.ref();
}
size_t InternalThreadPool::sizeOfIncludingThis(
mozilla::MallocSizeOf mallocSizeOf,
const AutoLockHelperThreadState& lock) const {
return sizeof(InternalThreadPool) +
threads(lock).sizeOfExcludingThis(mallocSizeOf);
}
/* static */
void InternalThreadPool::DispatchTask(JS::DispatchReason reason) {
Get().dispatchTask(reason);
}
void InternalThreadPool::dispatchTask(JS::DispatchReason reason) {
gHelperThreadLock.assertOwnedByCurrentThread();
queuedTasks++;
if (reason == JS::DispatchReason::NewTask) {
wakeup.notify_one();
} else {
// We're called from a helper thread right before returning to
// HelperThread::threadLoop. There we will check queuedTasks so there's no
// need to wake up any threads.
MOZ_ASSERT(reason == JS::DispatchReason::FinishedTask);
MOZ_ASSERT(!TlsContext.get(), "we should be on a helper thread");
}
}
void InternalThreadPool::notifyAll(const AutoLockHelperThreadState& lock) {
wakeup.notify_all();
}
void InternalThreadPool::wait(AutoLockHelperThreadState& lock) {
wakeup.wait_for(lock, mozilla::TimeDuration::Forever());
}
HelperThread::HelperThread()
: thread(Thread::Options().setStackSize(HELPER_STACK_SIZE)) {}
bool HelperThread::init(InternalThreadPool* pool) {
return thread.init(HelperThread::ThreadMain, pool, this);
}
void HelperThread::join() { thread.join(); }
/* static */
void HelperThread::ThreadMain(InternalThreadPool* pool, HelperThread* helper) {
ThisThread::SetName("JS Helper");
helper->ensureRegisteredWithProfiler();
helper->threadLoop(pool);
helper->unregisterWithProfilerIfNeeded();
}
void HelperThread::ensureRegisteredWithProfiler() {
if (profilingStack) {
return;
}
// Note: To avoid dead locks, we should not hold on the helper thread lock
// while calling this function. This is safe because the registerThread field
// is a WriteOnceData<> type stored on the global helper tread state.
JS::RegisterThreadCallback callback = HelperThreadState().registerThread;
if (callback) {
profilingStack =
callback("JS Helper", reinterpret_cast<void*>(GetNativeStackBase()));
}
}
void HelperThread::unregisterWithProfilerIfNeeded() {
if (!profilingStack) {
return;
}
// Note: To avoid dead locks, we should not hold on the helper thread lock
// while calling this function. This is safe because the unregisterThread
// field is a WriteOnceData<> type stored on the global helper tread state.
JS::UnregisterThreadCallback callback = HelperThreadState().unregisterThread;
if (callback) {
callback();
profilingStack = nullptr;
}
}
HelperThread::AutoProfilerLabel::AutoProfilerLabel(
HelperThread* helperThread, const char* label,
JS::ProfilingCategoryPair categoryPair)
: profilingStack(helperThread->profilingStack) {
if (profilingStack) {
profilingStack->pushLabelFrame(label, nullptr, this, categoryPair);
}
}
HelperThread::AutoProfilerLabel::~AutoProfilerLabel() {
if (profilingStack) {
profilingStack->pop();
}
}
void HelperThread::threadLoop(InternalThreadPool* pool) {
MOZ_ASSERT(CanUseExtraThreads());
AutoLockHelperThreadState lock;
while (!pool->terminating) {
if (pool->queuedTasks != 0) {
pool->queuedTasks--;
HelperThreadState().runOneTask(lock);
continue;
}
AUTO_PROFILER_LABEL("HelperThread::threadLoop::wait", IDLE);
pool->wait(lock);
}
}