(gdb) bt
#0  0xb7833424 in __kernel_vsyscall ()
#1  0xb7809619 in __lll_lock_wait () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/lowlevellock.S:142
#2  0xb7804f7d in _L_lock_708 () from /lib/i386-linux-gnu/libpthread.so.0
#3  0xb7804dc3 in __pthread_mutex_lock (mutex=0xa690014) at pthread_mutex_lock.c:61
#4  0xb6af4881 in boost::thread::interrupt() () from /usr/lib/libboost_thread.so.1.46.1
#5  0xb6b4d537 in gruel::thread_group::interrupt_all() () from /usr/local/lib/libgruel-3.5.0rc0.so.0.0.0
#6  0xb6cf249e in gr_scheduler_tpb::stop() () from /usr/local/lib/libgnuradio-core-3.5.0rc0.so.0.0.0
#7  0xb6cf7b76 in gr_top_block_impl::stop() () from /usr/local/lib/libgnuradio-core-3.5.0rc0.so.0.0.0
#8  0xb6cf7bcd in gr_top_block_impl::restart() () from /usr/local/lib/libgnuradio-core-3.5.0rc0.so.0.0.0
#9  0xb6cf83cf in gr_top_block_impl::unlock() () from /usr/local/lib/libgnuradio-core-3.5.0rc0.so.0.0.0
#10 0xb6cf720e in gr_top_block::unlock() () from /usr/local/lib/libgnuradio-core-3.5.0rc0.so.0.0.0
#11 0xb6ce04f3 in gr_hier_block2_detail::unlock() () from /usr/local/lib/libgnuradio-core-3.5.0rc0.so.0.0.0
#12 0xb6cde76e in gr_hier_block2::unlock() () from /usr/local/lib/libgnuradio-core-3.5.0rc0.so.0.0.0
#13 0xb70dd980 in _wrap_gr_hier_block2_sptr_unlock () from /usr/local/lib/python2.7/dist-packages/gnuradio/gr/_gnuradio_core_runtime.so
#14 0x080f77c3 in PyEval_EvalFrameEx ()
#15 0x080f7e20 in PyEval_EvalFrameEx ()
#16 0x080f7e20 in PyEval_EvalFrameEx ()
#17 0x080f7e20 in PyEval_EvalFrameEx ()
#18 0x080fd804 in PyEval_EvalCodeEx ()
#19 0x080fe177 in PyEval_EvalCode ()
#20 0x0811acd0 in ?? ()
#21 0x0811b8e9 in PyRun_FileExFlags ()
#22 0x0811c4cc in PyRun_SimpleFileExFlags ()
#23 0x0812c7c6 in Py_Main ()
#24 0x0805da0b in main ()