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src: refactor thread stopping mechanism #26757

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src: refactor thread stopping mechanism #26757

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47a0854
src: refactor thread stopping mechanism
addaleax Mar 18, 2019
3120670
fixup! src: refactor thread stopping mechanism
addaleax Mar 19, 2019
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10 changes: 9 additions & 1 deletion src/env-inl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -709,7 +709,7 @@ inline void Environment::remove_sub_worker_context(worker::Worker* context) {
}

inline bool Environment::is_stopping() const {
return thread_stopper_.IsStopped();
return thread_stopper_.is_stopped();
}

inline performance::performance_state* Environment::performance_state() {
Expand Down Expand Up @@ -979,6 +979,14 @@ void Environment::ForEachBaseObject(T&& iterator) {
}
}

bool AsyncRequest::is_stopped() const {
return stopped_.load();
}

void AsyncRequest::set_stopped(bool flag) {
stopped_.store(flag);
}

#define VP(PropertyName, StringValue) V(v8::Private, PropertyName)
#define VY(PropertyName, StringValue) V(v8::Symbol, PropertyName)
#define VS(PropertyName, StringValue) V(v8::String, PropertyName)
Expand Down
29 changes: 7 additions & 22 deletions src/env.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -340,13 +340,13 @@ void Environment::InitializeLibuv(bool start_profiler_idle_notifier) {
uv_unref(reinterpret_cast<uv_handle_t*>(&idle_prepare_handle_));
uv_unref(reinterpret_cast<uv_handle_t*>(&idle_check_handle_));

GetAsyncRequest()->Install(
thread_stopper()->Install(
this, static_cast<void*>(this), [](uv_async_t* handle) {
Environment* env = static_cast<Environment*>(handle->data);
uv_stop(env->event_loop());
});
GetAsyncRequest()->SetStopped(false);
uv_unref(reinterpret_cast<uv_handle_t*>(GetAsyncRequest()->GetHandle()));
thread_stopper()->set_stopped(false);
uv_unref(reinterpret_cast<uv_handle_t*>(thread_stopper()->GetHandle()));

// Register clean-up cb to be called to clean up the handles
// when the environment is freed, note that they are not cleaned in
Expand All @@ -365,7 +365,7 @@ void Environment::InitializeLibuv(bool start_profiler_idle_notifier) {

void Environment::ExitEnv() {
set_can_call_into_js(false);
GetAsyncRequest()->Stop();
thread_stopper()->Stop();
isolate_->TerminateExecution();
}

Expand Down Expand Up @@ -533,7 +533,7 @@ void Environment::RunCleanup() {
started_cleanup_ = true;
TraceEventScope trace_scope(TRACING_CATEGORY_NODE1(environment),
"RunCleanup", this);
GetAsyncRequest()->Uninstall();
thread_stopper()->Uninstall();
CleanupHandles();

while (!cleanup_hooks_.empty()) {
Expand Down Expand Up @@ -948,49 +948,34 @@ char* Environment::Reallocate(char* data, size_t old_size, size_t size) {
}

void AsyncRequest::Install(Environment* env, void* data, uv_async_cb target) {
Mutex::ScopedLock lock(mutex_);
CHECK_NULL(async_);
env_ = env;
async_ = new uv_async_t;
async_->data = data;
CHECK_EQ(uv_async_init(env_->event_loop(), async_, target), 0);
}

void AsyncRequest::Uninstall() {
Mutex::ScopedLock lock(mutex_);
if (async_ != nullptr) {
env_->CloseHandle(async_, [](uv_async_t* async) { delete async; });
async_ = nullptr;
}
}

void AsyncRequest::Stop() {
Mutex::ScopedLock lock(mutex_);
stop_ = true;
set_stopped(true);
if (async_ != nullptr) uv_async_send(async_);
}

void AsyncRequest::SetStopped(bool flag) {
Mutex::ScopedLock lock(mutex_);
stop_ = flag;
}

bool AsyncRequest::IsStopped() const {
Mutex::ScopedLock lock(mutex_);
return stop_;
}

uv_async_t* AsyncRequest::GetHandle() {
Mutex::ScopedLock lock(mutex_);
return async_;
}

void AsyncRequest::MemoryInfo(MemoryTracker* tracker) const {
Mutex::ScopedLock lock(mutex_);
if (async_ != nullptr) tracker->TrackField("async_request", *async_);
}

AsyncRequest::~AsyncRequest() {
Mutex::ScopedLock lock(mutex_);
CHECK_NULL(async_);
}

Expand Down
12 changes: 7 additions & 5 deletions src/env.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@
#include "uv.h"
#include "v8.h"

#include <atomic>
#include <cstdint>
#include <functional>
#include <list>
Expand Down Expand Up @@ -518,18 +519,19 @@ class AsyncRequest : public MemoryRetainer {
void Install(Environment* env, void* data, uv_async_cb target);
void Uninstall();
void Stop();
void SetStopped(bool flag);
bool IsStopped() const;
inline void set_stopped(bool flag);
inline bool is_stopped() const;
uv_async_t* GetHandle();
void MemoryInfo(MemoryTracker* tracker) const override;


SET_MEMORY_INFO_NAME(AsyncRequest)
SET_SELF_SIZE(AsyncRequest)

private:
Environment* env_;
uv_async_t* async_ = nullptr;
mutable Mutex mutex_;
bool stop_ = true;
std::atomic_bool stopped_ {true};
};

class Environment {
Expand Down Expand Up @@ -1048,7 +1050,7 @@ class Environment {
inline ExecutionMode execution_mode() { return execution_mode_; }

inline void set_execution_mode(ExecutionMode mode) { execution_mode_ = mode; }
inline AsyncRequest* GetAsyncRequest() { return &thread_stopper_; }
inline AsyncRequest* thread_stopper() { return &thread_stopper_; }

private:
inline void CreateImmediate(native_immediate_callback cb,
Expand Down
4 changes: 2 additions & 2 deletions src/node.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -832,14 +832,14 @@ inline int StartNodeWithIsolate(Isolate* isolate,
per_process::v8_platform.DrainVMTasks(isolate);

more = uv_loop_alive(env.event_loop());
if (more && !env.GetAsyncRequest()->IsStopped()) continue;
if (more && !env.is_stopping()) continue;

RunBeforeExit(&env);

// Emit `beforeExit` if the loop became alive either after emitting
// event, or after running some callbacks.
more = uv_loop_alive(env.event_loop());
} while (more == true && !env.GetAsyncRequest()->IsStopped());
} while (more == true && !env.is_stopping());
env.performance_state()->Mark(
node::performance::NODE_PERFORMANCE_MILESTONE_LOOP_EXIT);
}
Expand Down
7 changes: 4 additions & 3 deletions src/node_worker.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,7 @@ Worker::Worker(Environment* env,
bool Worker::is_stopped() const {
Mutex::ScopedLock lock(mutex_);
if (env_ != nullptr)
return env_->GetAsyncRequest()->IsStopped();
return env_->is_stopping();
return stopped_;
}

Expand Down Expand Up @@ -222,7 +222,7 @@ void Worker::Run() {
stopped_ = true;
this->env_ = nullptr;
}
env_->GetAsyncRequest()->SetStopped(true);
env_->thread_stopper()->set_stopped(true);
env_->stop_sub_worker_contexts();
env_->RunCleanup();
RunAtExit(env_.get());
Expand Down Expand Up @@ -381,7 +381,8 @@ void Worker::OnThreadStopped() {
Worker::~Worker() {
Mutex::ScopedLock lock(mutex_);

CHECK(stopped_ || env_ == nullptr || env_->GetAsyncRequest()->IsStopped());
CHECK(stopped_);
CHECK_NULL(env_);
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IIRC, there was a control flow that takes to Worker destructor without nullifying env_ , not able to figure that out now; do you know?

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@gireeshpunathil I think that would be a bug – the child thread is not allowed to exist at this point (and the next CHECK verifies that the thread has been joined), and the child thread in turn owns the Environment.

CHECK(thread_joined_);

Debug(this, "Worker %llu destroyed", thread_id_);
Expand Down