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fixed crash in the thread pool occurs because of enqueueing tasks before the thread pool starts #4583

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fixed crash in the thread pool occurs because of enqueueing tasks before the thread pool starts #4583

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08b671e
fixed crash in thread pool and added test
vladstepanyuk Oct 30, 2025
dac2122
correct issue
vladstepanyuk Oct 30, 2025
e4faf1a
replaced future promise with std::latch
vladstepanyuk Oct 31, 2025
1168b9a
added verify on thread pool stopped
vladstepanyuk Nov 5, 2025
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3 changes: 1 addition & 2 deletions cloud/storage/core/libs/common/thread_pool.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,7 @@ class TThreadPool final
worker.Name = TStringBuilder() << threadName << i++;
worker.Thread = std::make_unique<TWorkerThread>(*this, worker);
}
AtomicSet(RunningWorkers, NumWorkers);
}

~TThreadPool() override
Expand All @@ -97,8 +98,6 @@ class TThreadPool final

void Start() override
{
AtomicSet(RunningWorkers, NumWorkers);

for (auto& worker: Workers) {
worker.Thread->Start();
}
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33 changes: 33 additions & 0 deletions cloud/storage/core/libs/common/thread_pool_ut.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@

#include <util/generic/scope.h>

#include <thread>

namespace NCloud {

////////////////////////////////////////////////////////////////////////////////
Expand All @@ -30,6 +32,37 @@ Y_UNIT_TEST_SUITE(TThreadPoolTest)

UNIT_ASSERT_EQUAL(future.GetValue(WaitTimeout), 42);
}

Y_UNIT_TEST(ShouldExecuteTaskEnqueuedBeforeStart)
{
auto threadPool = CreateThreadPool("thread", 1);

auto promise = NThreading::NewPromise();

auto future = promise.GetFuture();

std::thread thread(
[threadPool, promise = std::move(promise)]() mutable
{
promise.SetValue();
auto future = threadPool->Execute([] { return 42; });

UNIT_ASSERT_EQUAL(future.GetValue(WaitTimeout), 42);
});

future.GetValueSync();

// Sleep to be sure that task will be enqueued before start.
Sleep(TDuration::Seconds(1));
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@sharpeye sharpeye Oct 30, 2025

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А если вызвать promise.SetValue(); после threadPool->Execute ?

Можно взять latch для синхронизации:

auto threadPool = CreateThreadPool("thread", 1);

std::latch enqueued{1};

std::thread thread([&] {
    auto future = threadPool->Execute([] { return 42; });
    enqueued.count_down();

    UNIT_ASSERT_EQUAL(42, future.GetValue(WaitTimeout));
});

enqueued.wait();

threadPool->Start();
threadPool->Stop();

thread.join();

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@vladstepanyuk vladstepanyuk Oct 30, 2025

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я хотел написать тест который будет крашиться в отсутствии фикса.
Если фикса нет, то threadPool->Execute зависнет пока не вызовется threadPool->Start() т.е. будет дедлок.
Как бы да зафейлится тест но хотелось бы краш
по хорошему надо было бы вставить count_down после AllocateWorker

nbs/cloud/storage/core/libs/common/thread_pool.cpp

Lines 120 to 127 in 155b318

void Enqueue(ITaskPtr task) override
{
Queue.Enqueue(std::move(task));
if (AllocateWorker()) {
WakeUpWorker();
}
}

но так сделать понятно не получится. Так что не понятно как воспроизвести стабильно краш без слипов и без того чтобы лезть в кишки тред пула

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@sharpeye sharpeye Oct 30, 2025

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enqueued.wait();
// Sleep to make it more likely that ReleaseWorker is called before starting the thread pool
Sleep(1s);
threadPool->Start();


threadPool->Start();
Y_DEFER
{
threadPool->Stop();
};

thread.join();
}
}

////////////////////////////////////////////////////////////////////////////////
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