[macos][qt] random deadlock on waitpid() when running vlc-qt-check
Sometimes, on macos, Qt stays stuck on vlc-qt-check code waiting on waitpid():
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
* frame #0: 0x0000000183c3e1f4 libsystem_kernel.dylib`mach_msg2_trap + 8
frame #1: 0x0000000183c50bbc libsystem_kernel.dylib`mach_msg2_internal + 232
frame #2: 0x0000000183c46e34 libsystem_kernel.dylib`mach_msg_overwrite + 476
frame #3: 0x0000000183c3e578 libsystem_kernel.dylib`mach_msg + 24
frame #4: 0x0000000183d5e680 CoreFoundation`__CFRunLoopServiceMachPort + 160
frame #5: 0x0000000183d5cf44 CoreFoundation`__CFRunLoopRun + 1208
frame #6: 0x0000000183d5c434 CoreFoundation`CFRunLoopRunSpecific + 608
frame #7: 0x0000000183dda45c CoreFoundation`CFRunLoopRun + 64
frame #8: 0x00000001000030a0 vlc-osx-static`main(i_argc=8, ppsz_argv=0x000000016fdff0d0) at darwinvlc.m:309:9 [opt]
frame #9: 0x00000001838f60e0 dyld`start + 2360
(lldb) thread backtrace all
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
* frame #0: 0x0000000183c3e1f4 libsystem_kernel.dylib`mach_msg2_trap + 8
frame #1: 0x0000000183c50bbc libsystem_kernel.dylib`mach_msg2_internal + 232
frame #2: 0x0000000183c46e34 libsystem_kernel.dylib`mach_msg_overwrite + 476
frame #3: 0x0000000183c3e578 libsystem_kernel.dylib`mach_msg + 24
frame #4: 0x0000000183d5e680 CoreFoundation`__CFRunLoopServiceMachPort + 160
frame #5: 0x0000000183d5cf44 CoreFoundation`__CFRunLoopRun + 1208
frame #6: 0x0000000183d5c434 CoreFoundation`CFRunLoopRunSpecific + 608
frame #7: 0x0000000183dda45c CoreFoundation`CFRunLoopRun + 64
frame #8: 0x00000001000030a0 vlc-osx-static`main(i_argc=8, ppsz_argv=0x000000016fdff0d0) at darwinvlc.m:309:9 [opt]
frame #9: 0x00000001838f60e0 dyld`start + 2360
thread #2, queue = 'org.videolan.vlc'
frame #0: 0x0000000183c45860 libsystem_kernel.dylib`__wait4 + 8
frame #1: 0x00000001036f66b0 libqt_plugin.dylib`OpenIntfCommon(vlc_object_t*, bool) [inlined] OpenInternal(p_intf=0x0000600001b79480) at qt.cpp:572:12 [opt]
frame #2: 0x00000001036f6650 libqt_plugin.dylib`OpenIntfCommon(p_this=0x0000600002058c00, dialogProvider=false) at qt.cpp:677:15 [opt]
frame #3: 0x0000000100652230 libvlccore.dylib`generic_start(func=<unavailable>, forced=<unavailable>, ap=<unavailable>) at modules.c:261:11 [opt]
frame #4: 0x0000000100652060 libvlccore.dylib`vlc_module_load(log=<unavailable>, capability="interface", name="qt", strict=<unavailable>, probe=(libvlccore.dylib`generic_start at modules.c:255)) at modules.c:230:15 [opt]
frame #5: 0x0000000100652188 libvlccore.dylib`module_need(obj=0x0000600002058c00, cap=<unavailable>, name=<unavailable>, strict=<unavailable>) at modules.c:272:24 [opt]
frame #6: 0x00000001006577bc libvlccore.dylib`intf_Create(libvlc=0x0000600000444000, chain="qt") at interface.c:173:24 [opt]
frame #7: 0x0000000100657c38 libvlccore.dylib`libvlc_InternalAddIntf(libvlc=0x0000600000444000, name=0x0000000000000000) at interface.c:278:15 [opt]
frame #8: 0x00000001000032b0 vlc-osx-static`__main_block_invoke_4(.block_descriptor=0x000060000204c600) at darwinvlc.m:291:13 [opt]
frame #9: 0x0000000183acc750 libdispatch.dylib`_dispatch_call_block_and_release + 32
frame #10: 0x0000000183ace3e8 libdispatch.dylib`_dispatch_client_callout + 20
frame #11: 0x0000000183ad5a14 libdispatch.dylib`_dispatch_lane_serial_drain + 748
frame #12: 0x0000000183ad6544 libdispatch.dylib`_dispatch_lane_invoke + 380
frame #13: 0x0000000183ae12d0 libdispatch.dylib`_dispatch_root_queue_drain_deferred_wlh + 288
frame #14: 0x0000000183ae0b44 libdispatch.dylib`_dispatch_workloop_worker_thread + 404
frame #15: 0x0000000183c7b00c libsystem_pthread.dylib`_pthread_wqthread + 288
thread #4, name = 'vlc-exec-runner'
frame #0: 0x0000000183c419ec libsystem_kernel.dylib`__psynch_cvwait + 8
frame #1: 0x0000000183c7f55c libsystem_pthread.dylib`_pthread_cond_wait + 1228
frame #2: 0x00000001006c8d18 libvlccore.dylib`vlc_atomic_wait(addr=0x000000017001ef40, value=0) at wait.c:86:9 [opt]
frame #3: 0x00000001006bb5f0 libvlccore.dylib`vlc_cond_wait(cond=0x0000600001b408d8, mutex=0x0000600001b40880) at threads.c:288:5 [opt]
frame #4: 0x00000001006b2eec libvlccore.dylib`ThreadRun [inlined] QueueTake(executor=0x0000600001b40880) at executor.c:98:9 [opt]
frame #5: 0x00000001006b2eac libvlccore.dylib`ThreadRun(userdata=0x0000600003b5c000) at executor.c:128:24 [opt]
frame #6: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #5, name = 'vlc-exec-runner'
frame #0: 0x0000000183c419ec libsystem_kernel.dylib`__psynch_cvwait + 8
frame #1: 0x0000000183c7f55c libsystem_pthread.dylib`_pthread_cond_wait + 1228
frame #2: 0x00000001006c8d18 libvlccore.dylib`vlc_atomic_wait(addr=0x000000017012af40, value=0) at wait.c:86:9 [opt]
frame #3: 0x00000001006bb5f0 libvlccore.dylib`vlc_cond_wait(cond=0x0000600001b43fd8, mutex=0x0000600001b43f80) at threads.c:288:5 [opt]
frame #4: 0x00000001006b2eec libvlccore.dylib`ThreadRun [inlined] QueueTake(executor=0x0000600001b43f80) at executor.c:98:9 [opt]
frame #5: 0x00000001006b2eac libvlccore.dylib`ThreadRun(userdata=0x0000600003b5c030) at executor.c:128:24 [opt]
frame #6: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #6, name = 'vlc-exec-runner'
frame #0: 0x0000000183c419ec libsystem_kernel.dylib`__psynch_cvwait + 8
frame #1: 0x0000000183c7f55c libsystem_pthread.dylib`_pthread_cond_wait + 1228
frame #2: 0x00000001006c8d18 libvlccore.dylib`vlc_atomic_wait(addr=0x0000000170236f40, value=0) at wait.c:86:9 [opt]
frame #3: 0x00000001006bb5f0 libvlccore.dylib`vlc_cond_wait(cond=0x0000600001b43f58, mutex=0x0000600001b43f00) at threads.c:288:5 [opt]
frame #4: 0x00000001006b2eec libvlccore.dylib`ThreadRun [inlined] QueueTake(executor=0x0000600001b43f00) at executor.c:98:9 [opt]
frame #5: 0x00000001006b2eac libvlccore.dylib`ThreadRun(userdata=0x0000600003b5c060) at executor.c:128:24 [opt]
frame #6: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #7, name = 'vlc-exec-runner'
frame #0: 0x0000000183c419ec libsystem_kernel.dylib`__psynch_cvwait + 8
frame #1: 0x0000000183c7f55c libsystem_pthread.dylib`_pthread_cond_wait + 1228
frame #2: 0x00000001006c8d18 libvlccore.dylib`vlc_atomic_wait(addr=0x0000000170342f40, value=0) at wait.c:86:9 [opt]
frame #3: 0x00000001006bb5f0 libvlccore.dylib`vlc_cond_wait(cond=0x0000600001b43ed8, mutex=0x0000600001b43e80) at threads.c:288:5 [opt]
frame #4: 0x00000001006b2eec libvlccore.dylib`ThreadRun [inlined] QueueTake(executor=0x0000600001b43e80) at executor.c:98:9 [opt]
frame #5: 0x00000001006b2eac libvlccore.dylib`ThreadRun(userdata=0x0000600003b5c090) at executor.c:128:24 [opt]
frame #6: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #8, name = 'vlc-exec-runner'
frame #0: 0x0000000183c419ec libsystem_kernel.dylib`__psynch_cvwait + 8
frame #1: 0x0000000183c7f55c libsystem_pthread.dylib`_pthread_cond_wait + 1228
frame #2: 0x00000001006c8d18 libvlccore.dylib`vlc_atomic_wait(addr=0x000000017044ef40, value=0) at wait.c:86:9 [opt]
frame #3: 0x00000001006bb5f0 libvlccore.dylib`vlc_cond_wait(cond=0x0000600001b43e58, mutex=0x0000600001b43e00) at threads.c:288:5 [opt]
frame #4: 0x00000001006b2eec libvlccore.dylib`ThreadRun [inlined] QueueTake(executor=0x0000600001b43e00) at executor.c:98:9 [opt]
frame #5: 0x00000001006b2eac libvlccore.dylib`ThreadRun(userdata=0x0000600003b5c0c0) at executor.c:128:24 [opt]
frame #6: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #9, name = 'caulk.messenger.shared:17'
frame #0: 0x0000000183c3e170 libsystem_kernel.dylib`semaphore_wait_trap + 8
frame #1: 0x000000018e1f7624 caulk`caulk::semaphore::timed_wait(double) + 212
frame #2: 0x000000018e1f74d8 caulk`caulk::concurrent::details::worker_thread::run() + 36
frame #3: 0x000000018e1f71d8 caulk`void* caulk::thread_proxy<std::__1::tuple<caulk::thread::attributes, void (caulk::concurrent::details::worker_thread::*)(), std::__1::tuple<caulk::concurrent::details::worker_thread*>>>(void*) + 96
frame #4: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #10, name = 'caulk.messenger.shared:high'
frame #0: 0x0000000183c3e170 libsystem_kernel.dylib`semaphore_wait_trap + 8
frame #1: 0x000000018e1f7624 caulk`caulk::semaphore::timed_wait(double) + 212
frame #2: 0x000000018e1f74d8 caulk`caulk::concurrent::details::worker_thread::run() + 36
frame #3: 0x000000018e1f71d8 caulk`void* caulk::thread_proxy<std::__1::tuple<caulk::thread::attributes, void (caulk::concurrent::details::worker_thread::*)(), std::__1::tuple<caulk::concurrent::details::worker_thread*>>>(void*) + 96
frame #4: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #12, name = 'vlc-player-end'
frame #0: 0x0000000183c419ec libsystem_kernel.dylib`__psynch_cvwait + 8
frame #1: 0x0000000183c7f55c libsystem_pthread.dylib`_pthread_cond_wait + 1228
frame #2: 0x00000001006c8d18 libvlccore.dylib`vlc_atomic_wait(addr=0x00000001706fef00, value=0) at wait.c:86:9 [opt]
frame #3: 0x00000001006bb5f0 libvlccore.dylib`vlc_cond_wait(cond=0x0000000134604890, mutex=0x0000000134604788) at threads.c:288:5 [opt]
frame #4: 0x0000000100682584 libvlccore.dylib`vlc_player_destructor_Thread(data=0x0000000134604770) at player.c:199:13 [opt]
frame #5: 0x0000000183c7ef94 libsystem_pthread.dylib`_pthread_start + 136
thread #15
frame #0: 0x0000000183c79d20 libsystem_pthread.dylib`start_wqthreadwarning: libqt_plugin.dylib was compiled with optimization - stepping may behave oddly; variables may not be available.
frame #1: 0x00000001036f66b0 libqt_plugin.dylib`OpenIntfCommon(vlc_object_t*, bool) [inlined] OpenInternal(p_intf=0x0000600001b79480) at qt.cpp:572:12 [opt]
569 return VLC_ENOMEM;
570
571 int status;
-> 572 while (waitpid(pid, &status, 0) == -1);
573
574 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
575 {
(lldb)
frame #2: 0x00000001036f6650 libqt_plugin.dylib`OpenIntfCommon(p_this=0x0000600002058c00, dialogProvider=false) at qt.cpp:677:15 [opt]
674 p_intf->isShuttingDown = false;
675 p_intf->refCount = 1;
676
-> 677 int ret = OpenInternal(p_intf);
678 if (ret != VLC_SUCCESS)
679 {
680 vlc_LogDestroy(p_intf->obj.logger);