Valgrind segfaults running threaded code under MacOS 10.14.6

[prjoh]

This seems to be a historic bug and is related to MacOS X libsystem_pthread.dylib.

This bug occurs on my system (Mac OS 10.14.6) when trying to run valgrind on a Qt for Python application.
Here the bug output:

==52109== Callgrind, a call-graph generating cache profiler
==52109== Copyright (C) 2002-2017, and GNU GPL'd, by Josef Weidendorfer et al.
==52109== Using Valgrind-3.16.0.GIT and LibVEX; rerun with -h for copyright info
==52109== Command: python main.py
==52109== 
==52109== For interactive control, run 'callgrind_control -h'.
--52109-- UNKNOWN mach_msg unhandled MACH_SEND_TRAILER option
--52109-- UNKNOWN mach_msg unhandled MACH_SEND_TRAILER option (repeated 2 times)
--52109-- UNKNOWN mach_msg unhandled MACH_SEND_TRAILER option (repeated 4 times)
==52109== 
==52109== Process terminating with default action of signal 11 (SIGSEGV)
==52109==  Access not within mapped region at address 0x18
==52109==    at 0x101BFA808: _pthread_wqthread_setup (in /usr/lib/system/libsystem_pthread.dylib)
==52109==    by 0x101BFA497: _pthread_wqthread (in /usr/lib/system/libsystem_pthread.dylib)
==52109==    by 0x101BFA3FC: start_wqthread (in /usr/lib/system/libsystem_pthread.dylib)
==52109==  If you believe this happened as a result of a stack
==52109==  overflow in your program's main thread (unlikely but
==52109==  possible), you can try to increase the size of the
==52109==  main thread stack using the --main-stacksize= flag.
==52109==  The main thread stack size used in this run was 16777216.
==52109== 
==52109== Events    : Ir
==52109== Collected : 1592614632
==52109== 
==52109== I   refs:      1,592,614,632

[LouisBrunner]

Hi @prjoh,

Thank you for your report! This is related to the lack of support for wqthread (#4), I have some patches in progress but nothing stable unfortunately. Please refer to the other issue for updates.

[prjoh]

Sorry for missing that report and thanks for the quick response!