info threads
* 2 process 7220  0xffffe410 in __kernel_vsyscall ()
  1 process 7212  0xb7eb4cbf in ?? () from /usr/lib/libmozjs.so.0d

(gdb) bt
#0  0xb7eb4cbf in ?? () from /usr/lib/libmozjs.so.0d
#1  0x08191a08 in ?? ()
#2  0x00000000 in ?? ()
(gdb) thread 2
[Switching to thread 2 (process 7220)]#0  0xffffe410 in __kernel_vsyscall ()
(gdb) bt
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7c26f31 in __lll_mutex_unlock_wake () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb7c23c98 in _L_mutex_unlock_175 () from /lib/tls/i686/cmov/libpthread.so.0
#3  0xb7c23984 in __pthread_mutex_unlock_usercnt () from /lib/tls/i686/cmov/libpthread.so.0
#4  0x08117a05 in WorkerThread (arg=0x816d060) at ../threadutil/src/ThreadPool.c:568
#5  0xb7c2046b in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#6  0xb7ba46de in clone () from /lib/tls/i686/cmov/libc.so.6