Many core dumps in pthread_getspecific - how to debug?

[ortadur at web.de]

   Hi,

   I'm new to FreeBSD, and it looks nice so far. There is just one thing
   which bugs me. I'm getting a lot of core dumps in many different
   programmes like Xorg, vim, firefox, ... and looking into the backtrace
   it's always inside pthread_getspecific () from /lib/libthr.so.3.

   You can imagine that especially Xorg is very annoying. I'm using
   awesome as a window manager and I'm always up to date with the latest
   patches. Sometimes it's crashing multiple times a day, sometimes a few
   days without a core dump. This week I'd just 1 core dump of vim, the
   last week I'd 11 core dumps from Xorg and also some more from other
   programmes.

   I didn't found /lib/libthr.so.3 inside the ports, so I guess it's part
   of the base system. The typical backtrace looks like this (not always
   exactly the same, but always ends up at pthread_getspecific):

   [New Thread 803c07c00 (LWP 100601/Xorg)]
   [New Thread 803c06400 (LWP 100205/Xorg)]
   (gdb) bt
   #0  0x00000008014816a2 in pthread_getspecific () from /lib/libthr.so.3
   #1  0x00000008014815ed in pthread_getspecific () from /lib/libthr.so.3
   #2  0x0000000801483b01 in pthread_mutex_unlock () from /lib/libthr.so.3
   #3  0x000000080266afe8 in sbrk () from /lib/libc.so.7
   #4  0x000000080266b251 in sbrk () from /lib/libc.so.7
   #5  0x0000000802674264 in realloc () from /lib/libc.so.7
   #6  0x000000000059c988 in ReadRequestFromClient ()
   #7  0x00000000004353f9 in UpdateCurrentTimeIf ()
   #8  0x000000000042a007 in _start ()
   #9  0x0000000000429aff in _start ()
   #10 0x0000000800816000 in ?? ()
   #11 0x0000000000000000 in ?? ()

   % uname -a
   FreeBSD andre 10.1-RELEASE-p10 FreeBSD 10.1-RELEASE-p10 #0: Wed May 13
   06:54:13 UTC 2015
   root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64

   It's running on real hardware, it's not a VM.

   And now the questions:
   What do I have to do to debug this and get rid of this bug?
   Whom do I need to send those debug infos?

   Sincerely yours Andre.