Re: thread problem

Patrick,

Please re-run your test with the latest CVS version of GraphicsMagick.
I have added some logic to make sure that pthread_mutex_unlock is not
called on an unlocked mutex.  I have also added an assertion which
should trip if a different thread than the locking thread attempts to
unlock the mutex.

Bob

On Thu, 1 May 2003, Patrick Welche wrote:

> NetBSD now as a debugging libpthread, which shows up the following:
>
> Error detected, file "/usr/src/lib/libpthread/pthread_mutex.c", line 338, function "pthread_mutex_unlock": Unlocking mutex owned by another thread.
>
> Normally the program should then dump core like the debugging malloc(), but
> for some reason it doesn't.. ImageMagick, does leave a core behind, which
> may give some clues? (both with display)
>
> #0  0x485e4817 in kill () from /usr/lib/libc.so.12
> #1  0x485ac149 in pthread__errorfunc () from /usr/lib/libpthread.so.0
> #2  0x485a902f in pthread_mutex_unlock () from /usr/lib/libpthread.so.0
> #3  0x480ed2e1 in UnlockSemaphoreInfo (semaphore_info=0x808be00)
>     at semaphore.c:425
> #4  0x480ed0f9 in DestroySemaphoreInfo (semaphore_info=0x809b078)
>     at semaphore.c:265
> #5  0x48087396 in DestroyCacheInfo (cache=0x809a000) at cache.c:957
> #6  0x48087602 in DestroyPixelCache (image=0x8098000) at cache.c:1073
> #7  0x4808757b in DestroyImagePixels (image=0x8098000) at cache.c:1041
> #8  0x480a2bea in DestroyImage (image=0x8098000) at image.c:1896
> #9  0x480ab08e in SetImageInfo (image_info=0x8093000, rectify=0,
>     exception=0xbfbff9a8) at image.c:5810
> #10 0x4809de61 in ReadImage (image_info=0x808d000, exception=0xbfbff9a8)
>     at constitute.c:2616
> #11 0x8049fae in main (argc=2, argv=0x805b000) at display.c:437
> #12 0x8049464 in ___start ()
>
> Looking at semaphore.c, I don't see why there is a
> static pthread_mutex_t semaphore_mutex
> and then things pass SemaphoreInfo->mutex around.
>
> So, what are these mutices used for, and would ditching the static one
> and seeing what breaks be a sensible way to find out why one thread is
> unlocking another thread's mutex?
>
> Cheers,
>
> Patrick
>
>
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======================================
Bob Friesenhahn
[email protected]
http://www.simplesystems.org/users/bfriesen



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