Hello,

I have an odd problem with QtService (http://qt.gitorious.org/qt-solutions) on Linux (Debian stable):

When starting my daemon during boot (via init script), the process receives a segfault in QMutex::unlock. This seems to happen *after* the background process is forked, since the service process is actually running once booting is completed.

I can not reproduce this by (re-) starting the service once the system is up, it happens only during boot. Also the segfault does not happen on every boot, but only about 80% of the time, so it seems to be a race condition.

The crash also happens when I remove all of my service implementation except for minimal skeleton code, so I'm pretty sure this problem is not a side effect of my code.

Qt Code: 
  1. Program terminated with signal 11, Segmentation fault.
  2. #0  0xb7209c6c in QMutex::unlock (this=0x9a07f88) at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qmutex.cpp:370
  3. 370	               "A mutex must be unlocked in the same thread that locked it.");
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Backtrace:
Qt Code: 
  1. Thread 2 (Thread 936):
  2. #0  0xb7800424 in __kernel_vsyscall ()
  3. #1  0xb717ffcf in __pthread_cond_wait (cond=0x9a07f48, mutex=0x9a07f30) at pthread_cond_wait.c:153
  4. #2  0xb72119fb in QWaitConditionPrivate::wait (this=0x9a07f30, time=4294967295)
  5.     at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qwaitcondition_unix.cpp:88
  6. #3  0xb72117ff in QWaitCondition::wait (this=0x9a09b88, mutex=0x9a09b70, time=4294967295)
  7.     at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qwaitcondition_unix.cpp:160
  8. #4  0xb7210fa3 in QThread::wait (this=0xb74b3794, time=4294967295)
  9.     at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qthread_unix.cpp:745
  10. #5  0xb730349d in ~QProcessManager (this=0xb74b3794, __in_chrg=<value optimized out>)
  11.     at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/io/qprocess_unix.cpp:208
  12. #6  0xb6f242df in __run_exit_handlers (status=0, listp=0xb7038304, run_list_atexit=true) at exit.c:78
  13. #7  0xb6f2434f in *__GI_exit (status=0) at exit.c:100
  14. #8  0xb6f0bcae in __libc_start_main (main=0x80520c4 <main>, argc=1, ubp_av=0xbfa8c674, init=0x8075480 <__libc_csu_init>, fini=0x8075470 <__libc_csu_fini>, 
  15.     rtld_fini=0xb780f380 <_dl_fini>, stack_end=0xbfa8c66c) at libc-start.c:260
  16. #9  0x08052031 in _start ()
  17.  
  18. Thread 1 (Thread 974):
  19. #0  0xb7209c6c in QMutex::unlock (this=0x9a07f88) at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qmutex.cpp:370
  20. #1  0xb71ed78a in QMutexLocker::unlock (this=0xb68b6250) at ../../include/QtCore/../../../qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qmutex.h:114
  21. #2  0xb71ed747 in ~QMutexLocker (this=0xb68b6250, __in_chrg=<value optimized out>)
  22.     at ../../include/QtCore/../../../qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qmutex.h:108
  23. #3  0xb73669f1 in QEventDispatcherGlibPrivate (this=0x9a09fa8, context=0x0)
  24.     at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/kernel/qeventdispatcher_glib.cpp:299
  25. #4  0xb7366da2 in QEventDispatcherGlib (this=0x9a09b10, parent=0x0)
  26.     at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/kernel/qeventdispatcher_glib.cpp:357
  27. #5  0xb7210390 in QThreadPrivate::createEventDispatcher (data=0x9a09c20)
  28.     at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qthread_unix.cpp:272
  29. #6  0xb72104d9 in QThreadPrivate::start (arg=0xb74b3794) at /home/build/dev/qt-everywhere-opensource-src-4.7.4/src/corelib/thread/qthread_unix.cpp:324
  30. #7  0xb717b955 in start_thread (arg=0xb68b6b70) at pthread_create.c:300
  31. #8  0xb6fc158e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130
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Does anyone have an idea what the problem might be?

Also, is there some kind of community support (bug tracker, discussion forum/list) for QtService/Qt-Solutions?