diff --git a/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared_until.pass.cpp b/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared_until.pass.cpp --- a/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared_until.pass.cpp +++ b/libcxx/test/std/thread/thread.mutex/thread.mutex.requirements/thread.sharedtimedmutex.requirements/thread.sharedtimedmutex.class/try_lock_shared_until.pass.cpp @@ -9,8 +9,6 @@ // UNSUPPORTED: libcpp-has-no-threads // UNSUPPORTED: c++98, c++03, c++11 -// ALLOW_RETRIES: 2 - // shared_timed_mutex was introduced in macosx10.12 // UNSUPPORTED: with_system_cxx_lib=macosx10.11 // UNSUPPORTED: with_system_cxx_lib=macosx10.10 @@ -39,44 +37,42 @@ typedef std::chrono::milliseconds ms; typedef std::chrono::nanoseconds ns; -ms WaitTime = ms(250); +ms SuccessWaitTime = ms(5000); // Some machines are busy or slow or both +ms FailureWaitTime = ms(50); -// Thread sanitizer causes more overhead and will sometimes cause this test -// to fail. To prevent this we give Thread sanitizer more time to complete the -// test. -#if !defined(TEST_HAS_SANITIZERS) -ms Tolerance = ms(50); -#else -ms Tolerance = ms(50 * 5); -#endif +// On busy or slow machines, there can be a significant delay between thread +// creation and thread start, so we use an atomic variable to signal that the +// thread is actually executing. +static std::atomic countDown; void f1() { + --countDown; time_point t0 = Clock::now(); - assert(m.try_lock_shared_until(Clock::now() + WaitTime + Tolerance) == true); + assert(m.try_lock_shared_until(Clock::now() + SuccessWaitTime) == true); time_point t1 = Clock::now(); m.unlock_shared(); - ns d = t1 - t0 - WaitTime; - assert(d < Tolerance); // within 50ms + assert(t1 - t0 <= SuccessWaitTime); } void f2() { time_point t0 = Clock::now(); - assert(m.try_lock_shared_until(Clock::now() + WaitTime) == false); - time_point t1 = Clock::now(); - ns d = t1 - t0 - WaitTime; - assert(d < Tolerance); // within tolerance + assert(m.try_lock_shared_until(Clock::now() + FailureWaitTime) == false); + assert(Clock::now() - t0 >= FailureWaitTime); } int main(int, char**) { + int threads = 5; { + countDown.store(threads); m.lock(); std::vector v; - for (int i = 0; i < 5; ++i) + for (int i = 0; i < threads; ++i) v.push_back(std::thread(f1)); - std::this_thread::sleep_for(WaitTime); + while (countDown > 0) + std::this_thread::yield(); m.unlock(); for (auto& t : v) t.join(); @@ -84,12 +80,11 @@ { m.lock(); std::vector v; - for (int i = 0; i < 5; ++i) + for (int i = 0; i < threads; ++i) v.push_back(std::thread(f2)); - std::this_thread::sleep_for(WaitTime + Tolerance); - m.unlock(); for (auto& t : v) t.join(); + m.unlock(); } return 0;