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Published 20 hours ago • verified publisher icon LadybirdBrowser

LibCore: Fix ThreadedPromise issues found with ThreadSanitizer

Open rcorsi opened this issue 2 months ago • 2 comments

Four data race warnings reported while running test TestLibCorePromise (from file Tests/LibCore/TestLibCorePromise.cpp) under ThreadSanitizer in g++. (See pull request #6034)

Attaching complete log of TestLibCorePromise test run with ThreadSanitizer

ThreadSanitizer_TestLibCorePromise.log

Explanations:

  1. Two warnings (one in test case threaded_promise_instantly_resolved and one in threaded_promise_resolved_later) about a data race in ThreadedPromise with m_has_completed flag variable access not controlled when accessed from multiple threads. To resolve the data race the class variable m_has_completed changed to Atomic to make the access controlled.
WARNING: ThreadSanitizer: data race (pid=63130)
  Read of size 1 at 0x722800000138 by main thread (mutexes: write M0):
    #0 Core::ThreadedPromise<int, AK::Error>::has_completed() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:65 (TestLibCorePromise+0x38a35) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #1 Core::ThreadedPromise<int, AK::Error>::await() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:70 (TestLibCorePromise+0x38a35)
    #2 __test_threaded_promise_instantly_resolved /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:150 (TestLibCorePromise+0x38a35)
    #3 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #4 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #5 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #6 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #7 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

  Previous write of size 1 at 0x722800000138 by thread T1:
    #0 Core::ThreadedPromise<int, AK::Error>::resolve(int&&)::{lambda()#1}::operator()() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:39 (TestLibCorePromise+0x36919) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #1 void Core::ThreadedPromise<int, AK::Error>::when_error_handler_is_ready<Core::ThreadedPromise<int, AK::Error>::resolve(int&&)::{lambda()#1}>(Core::ThreadedPromise<int, AK::Error>::resolve(int&&)::{lambda()#1}) /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:177 (TestLibCorePromise+0x39f19) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #2 Core::ThreadedPromise<int, AK::Error>::resolve(int&&) /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:34 (TestLibCorePromise+0x274c4) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #3 operator() /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:133 (TestLibCorePromise+0x274c4)
    #4 call /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x274c4)
    #5 AK::Function<long ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-threading.so.0+0xff9f) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)
    #6 operator() /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:80 (liblagom-threading.so.0+0xff9f)
    #7 _FUN /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:98 (liblagom-threading.so.0+0x10320) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)

  Location is heap block of size 160 at 0x7228000000a0 allocated by main thread:
    #0 operator new(unsigned long) ../../../../src/libsanitizer/tsan/tsan_new_delete.cpp:64 (libtsan.so.2+0xa84c0) (BuildId: f20c41defecd9fb4a975b3090b18de14b9117ffc)
    #1 Core::ThreadedPromise<int, AK::Error>::create() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:26 (TestLibCorePromise+0x29d15) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #2 __test_threaded_promise_instantly_resolved /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:129 (TestLibCorePromise+0x38250) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #3 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #4 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #5 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #6 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #7 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

  Mutex M0 (0x722800000108) created at:
    #0 pthread_mutex_init ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1345 (libtsan.so.2+0x5a00a) (BuildId: f20c41defecd9fb4a975b3090b18de14b9117ffc)
    #1 Threading::Mutex::Mutex() /home/bobo/projects/myladybird/Libraries/LibThreading/Mutex.h:29 (TestLibCorePromise+0x29e97) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #2 Core::ThreadedPromise<int, AK::Error>::ThreadedPromise() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:181 (TestLibCorePromise+0x29e97)
    #3 Core::ThreadedPromise<int, AK::Error>::create() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:26 (TestLibCorePromise+0x29e97)
    #4 __test_threaded_promise_instantly_resolved /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:129 (TestLibCorePromise+0x38250) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #5 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #6 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #7 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #8 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #9 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

  Thread T1 (tid=63132, finished) created by main thread at:
    #0 pthread_create ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1041 (libtsan.so.2+0x5b3b7) (BuildId: f20c41defecd9fb4a975b3090b18de14b9117ffc)
    #1 Threading::Thread::start() /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:73 (liblagom-threading.so.0+0xfd39) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)
    #2 __test_threaded_promise_instantly_resolved /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:136 (TestLibCorePromise+0x384c1) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #3 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #4 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #5 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #6 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #7 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

SUMMARY: ThreadSanitizer: data race /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:65 in Core::ThreadedPromise<int, AK::Error>::has_completed()
  1. One warning about a small issue with a bool flag (unblock_thread) in test case threaded_promise_resolved_later. This flag was being used in multiple threads to control the flow of the test and changing the variable to Atomic resolved the data race issue.
Running test 'threaded_promise_resolved_later'.
==================
WARNING: ThreadSanitizer: data race (pid=63130)
  Write of size 1 at 0x7fffffffd265 by main thread:
    #0 operator() /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:189 (TestLibCorePromise+0x1ec3d) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #1 call /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x1ec3d)
    #2 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-core.so.0+0xbb585) (BuildId: 37b8757494239f4cfa50cca02c173f6819ce8dcd)
    #3 Core::ThreadEventQueue::process() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadEventQueue.cpp:118 (liblagom-core.so.0+0xbb585)
    #4 Core::EventLoopImplementationUnix::pump(Core::EventLoopImplementation::PumpMode) /home/bobo/projects/myladybird/Libraries/LibCore/EventLoopImplementationUnix.cpp:309 (liblagom-core.so.0+0xdfcc8) (BuildId: 37b8757494239f4cfa50cca02c173f6819ce8dcd)
    #5 Core::EventLoop::pump(Core::EventLoop::WaitMode) /home/bobo/projects/myladybird/Libraries/LibCore/EventLoop.cpp:102 (liblagom-core.so.0+0x8f862) (BuildId: 37b8757494239f4cfa50cca02c173f6819ce8dcd)
    #6 Core::ThreadedPromise<int, AK::Error>::await() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:71 (TestLibCorePromise+0x377d6) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #7 __test_threaded_promise_resolved_later /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:191 (TestLibCorePromise+0x377d6)
    #8 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #9 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #10 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #11 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #12 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

  Previous read of size 1 at 0x7fffffffd265 by thread T2:
    #0 operator() /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:170 (TestLibCorePromise+0x26dfe) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #1 call /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x26dfe)
    #2 AK::Function<long ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-threading.so.0+0xff9f) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)
    #3 operator() /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:80 (liblagom-threading.so.0+0xff9f)
    #4 _FUN /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:98 (liblagom-threading.so.0+0x10320) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)

  Location is stack of main thread.

  Location is global '<null>' at 0x000000000000 ([stack]+0x20265)

  Thread T2 (tid=63133, running) created by main thread at:
    #0 pthread_create ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1041 (libtsan.so.2+0x5b3b7) (BuildId: f20c41defecd9fb4a975b3090b18de14b9117ffc)
    #1 Threading::Thread::start() /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:73 (liblagom-threading.so.0+0xfd39) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)
    #2 __test_threaded_promise_resolved_later /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:175 (TestLibCorePromise+0x37112) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #3 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #4 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #5 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #6 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #7 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

SUMMARY: ThreadSanitizer: data race /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:189 in operator()
  1. One warning about a small issue with a bool flag (resolved) in test case threaded_promise_instantly_resolved. This issue required no specific change to resolve, it was automatically resolved when item 1 in this list was fixed.
WARNING: ThreadSanitizer: data race (pid=63130)
  Read of size 1 at 0x7fffffffd29e by main thread:
    #0 void Test::expect<bool>(bool const&, AK::StringView, AK::SourceLocation) /home/bobo/projects/myladybird/Libraries/LibTest/Macros.h:36 (TestLibCorePromise+0x30904) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #1 __test_threaded_promise_instantly_resolved /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:152 (TestLibCorePromise+0x38ba4) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #2 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #3 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #4 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #5 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #6 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

  Previous write of size 1 at 0x7fffffffd29e by thread T1:
    #0 operator() /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:142 (TestLibCorePromise+0x25d07) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #1 operator() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:89 (TestLibCorePromise+0x25d07)
    #2 call /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x25d07)
    #3 AK::Function<AK::ErrorOr<void, AK::Error> (int&&)>::operator()(int&&) const /home/bobo/projects/myladybird/AK/Function.h:148 (TestLibCorePromise+0x36893) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #4 Core::ThreadedPromise<int, AK::Error>::resolve(int&&)::{lambda()#1}::operator()() /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:36 (TestLibCorePromise+0x36893)
    #5 void Core::ThreadedPromise<int, AK::Error>::when_error_handler_is_ready<Core::ThreadedPromise<int, AK::Error>::resolve(int&&)::{lambda()#1}>(Core::ThreadedPromise<int, AK::Error>::resolve(int&&)::{lambda()#1}) /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:177 (TestLibCorePromise+0x39f19) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #6 Core::ThreadedPromise<int, AK::Error>::resolve(int&&) /home/bobo/projects/myladybird/Libraries/LibCore/ThreadedPromise.h:34 (TestLibCorePromise+0x274c4) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #7 operator() /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:133 (TestLibCorePromise+0x274c4)
    #8 call /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x274c4)
    #9 AK::Function<long ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-threading.so.0+0xff9f) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)
    #10 operator() /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:80 (liblagom-threading.so.0+0xff9f)
    #11 _FUN /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:98 (liblagom-threading.so.0+0x10320) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)

  Location is stack of main thread.

  Location is global '<null>' at 0x000000000000 ([stack]+0x2029e)

  Thread T1 (tid=63132, finished) created by main thread at:
    #0 pthread_create ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1041 (libtsan.so.2+0x5b3b7) (BuildId: f20c41defecd9fb4a975b3090b18de14b9117ffc)
    #1 Threading::Thread::start() /home/bobo/projects/myladybird/Libraries/LibThreading/Thread.cpp:73 (liblagom-threading.so.0+0xfd39) (BuildId: a2f7c41a8dce5e480ab74ec02ffa37d09e7375b5)
    #2 __test_threaded_promise_instantly_resolved /home/bobo/projects/myladybird/Tests/LibCore/TestLibCorePromise.cpp:136 (TestLibCorePromise+0x384c1) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #3 AK::Function<void ()>::CallableWrapper<void (*)()>::call() /home/bobo/projects/myladybird/AK/Function.h:225 (TestLibCorePromise+0x2792c) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)
    #4 AK::Function<void ()>::operator()() const /home/bobo/projects/myladybird/AK/Function.h:148 (liblagom-test.so+0x212c4) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #5 Test::TestSuite::run(AK::Vector<AK::NonnullRefPtr<Test::TestCase>, 0ul, (AK::FastLastAccess)0> const&) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:195 (liblagom-test.so+0xf5cd) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #6 Test::TestSuite::main(AK::ByteString const&, AK::Span<AK::StringView>) /home/bobo/projects/myladybird/Libraries/LibTest/TestSuite.cpp:147 (liblagom-test.so+0xd318) (BuildId: ccb4d3c7dfe19d4c7eb8411a1293c2b3e68b77b4)
    #7 main /home/bobo/projects/myladybird/Libraries/LibTest/TestMain.cpp:26 (TestLibCorePromise+0x1df05) (BuildId: 134766ece94da3edc73e31fff39909b6d727b969)

SUMMARY: ThreadSanitizer: data race /home/bobo/projects/myladybird/Libraries/LibTest/Macros.h:36 in void Test::expect<bool>(bool const&, AK::StringView, AK::SourceLocation)
==================
Completed test 'threaded_promise_instantly_resolved' in 92ms

rcorsi avatar Sep 02 '25 18:09 rcorsi

Is number 2 even a data race? There is only one writer right?

R-Goc avatar Sep 02 '25 18:09 R-Goc

Is number 2 even a data race? There is only one writer right?

One thread is reading and one is writing to the same location.

Generally you shouldn't read a memory location in one thread while a write might be happening to the same location in another thread. That is a data race.

TSAN is just seeing this and reporting. If these particular cases could actually cause problems, that I can't guarantee.

Also if a variable is Atomic it will warn the optimizer that it could be used in multiple threads and not optimize it incorrectly. Sometimes people use volatile in the same way to help hint to not optimize out a variable.

rcorsi avatar Sep 02 '25 20:09 rcorsi

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions!

github-actions[bot] avatar Sep 24 '25 02:09 github-actions[bot]

Hello!

One or more of the commit messages in this PR do not match the Ladybird code submission policy, please check the lint_commits CI job for more details on which commits were flagged and why. Please do not close this PR and open another, instead modify your commit message(s) with git commit --amend and force push those changes to update this PR.

ladybird-bot avatar Sep 25 '25 01:09 ladybird-bot