https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101978
lewis pringle <lewis at sophists dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |lewis at sophists dot com
--- Comment #5 from lewis pringle <lewis at sophists dot com> ---
I have a (limited) trace of some of my code running into this problem. And even
without the code, the trace is strongly enough suggestive of where the problem
is I thought it worth including:
TSAN_OPTIONS="detect_deadlocks=0
suppressions=/Sandbox/Stroika-Dev//Tests/ThreadSanitizerSuppressions_qCompiler_SanitizerDoubleLockWithConditionVariables_Buggy.supp"
Builds/g++-debug-sanitize_thread/Tests/Test40
139746996119104] ENtering lock
139747039984064]ENtering try_lock_for
139747039984064]and the try_lock_for returned 0
139747039984064]ENtering try_lock_for
139747039984064]and the try_lock_for returned 0
139746996119104] Entering unlock
139747039984064]ENtering try_lock_for
139747039984064]and the try_lock_for returned 1
139747039984064] Entering unlock
==================
WARNING: ThreadSanitizer: unlock of an unlocked mutex (or by a wrong thread)
(pid=271643)
#0 pthread_mutex_unlock <null> (Test40+0x8a4a88)
#1 __gthread_mutex_unlock
/usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:779 (Test40+0x943790)
#2 __gthread_recursive_mutex_unlock
/usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:832 (Test40+0x943800)
#3 std::recursive_timed_mutex::unlock() <null> (Test40+0x97621d)
#4 unlock /Sandbox/Stroika-Dev/Tests/40/Test.cpp:1380 (Test40+0x94ee9f)
#5 unlock /usr/include/c++/11/bits/unique_lock.h:195 (Test40+0x968fed)
#6 ~unique_lock /usr/include/c++/11/bits/unique_lock.h:104
(Test40+0x95f342)
#7 ~ReadableReference
/Sandbox/Stroika-Dev/Library/Sources/Stroika/Foundation/Characters/../Execution/Synchronized.inl:447
(Test40+0x95849c)
it appears the problem is that (at least one) problem is that use of
try_lock_for () - when it acquires a lock - appears to not do the same
bookkeeping as lock, so that TSAN knows the lock happened and in what thread.
This COULD POSSIBLY be the same root cause of the problems with condition
variables (or maybe unrelated I suppose).
I dont know how TSAN does its magic/tracking, but I'd start looking at if
try_lock_for appears to similar stuff to lock...
