[Interest] Will TSAN_OPTIONS=detect_deadlocks=1 work when Qt is compiled with -sanitize thread?

[coroberti]

dtruss is available on Mac
https://stackoverflow.com/questions/31045575/how-to-trace-system-calls-of-a-program-in-mac-os-x

When the deadlock happens, perhaps you  could see the system calls and
which syscall in which thread is stacked.

Either by a system call tracer or by connecting a debugger (if your
software with debugging symbols reproducing it)
could give a clue in which area it happens. From here - thinking.

Kind regards,
Robert Iakobashvili
............................


On Thu, Jul 18, 2024 at 6:48 PM Nuno Santos <nuno.santos at imaginando.pt>
wrote:

> Robert,
>
> Thanks for your reply. I’m on MacOS and strace does not seem to be
> available.
>
> This deadlocks are very rare on MacOS and more frequent on iOS but this is
> mostly reported by our users. When developing we are rarely faced with this
> dead locks and when they happen I find myself wondering why they happen.
> And since they are so rare to reproduce it becomes even more difficult to
> find a solution.
>
> That is why I’m looking for tools that could help me identify the problem
> in a more sistematic way.
>
> Thank you!
>
> Regards,
>
> Nuno
>
> On 18 Jul 2024, at 16:41, coroberti <coroberti at gmail.com> wrote:
>
> Nuno,
> if you are on linux, *strace *command could be helpful to see and analyse
> all system calls.
> Thus, you could see how you are coming to a deadlock, if any.
>
> Kind regards,
> Robert Iakobashvili
> ............................
>
>
> On Thu, Jul 18, 2024 at 6:31 PM Nuno Santos via Interest <
> interest at qt-project.org> wrote:
>
>> Hi,
>>
>> Thanks for your reply.
>>
>> I’ve compiled Qt with -sanitize thread and I’m trying to find deadlock on
>> my application.
>>
>> Regards,
>>
>> Nuno
>>
>> > On 18 Jul 2024, at 16:15, Dennis Luehring via Interest <
>> interest at qt-project.org> wrote:
>> >
>> > Am 18.07.2024 um 17:07 schrieb Nuno Santos via Interest:
>> >>
>> https://github.com/google/sanitizers/wiki/ThreadSanitizerDeadlockDetector
>> >>
>> >> "Just use TSAN_OPTIONS=detect_deadlocks=1 when running your
>> tsan-instrumented program.”
>> >>
>> >
>> > this document is from 2015 - lock order inversion aka Deadlock detection
>> > is a feature that is active per default
>> > or better said i've used TSAN many times to find deadlocks - maybe its a
>> > special feature but seems to be the default now
>> >
>> > beware: you should always use recent gcc or clang for TSAN/ASAN as they
>> > evolve permanently - older compiler instrumentation just don't be that
>> good
>> > in detecting - im normaly using SUSE Tumbleweed with latest available
>> > gcc/clang for a my "bug hunting" environment
>> >
>> > do you try to find a Deadlock inside Qt code or inside your application
>> > - for the first a TSAN build of Qt would be better to prevent false
>> > positives
>> >
>> >
>> >
>> > _______________________________________________
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>> > Interest at qt-project.org
>> > https://lists.qt-project.org/listinfo/interest
>>
>> _______________________________________________
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