Thread 4 (Thread 1090541904 (LWP 13454)):
#0  0x00002b2d4413c03d in sem_wait () from /lib/libpthread.so.0
#1  0x00002b2d43eaa3d8 in PyThread_acquire_lock (lock=0x9e92c0, waitflag=1) at Python/thread_pthread.h:349
#2  0x00002b2d43e89034 in PyEval_RestoreThread (tstate=0x137fee0) at Python/ceval.c:312
#3  0x00002b2d43ea160a in PyGILState_Ensure () at Python/pystate.c:578
#4  0x00002b2d45547e45 in pyg_toggle_notify (data=0x10fa2d0, object=0x0, is_last_ref=0) at pygobject.c:632
#5  0x00002b2d45790994 in IA__g_object_ref (_object=<value optimized out>) at gobject.c:1730
#6  0x00002aaaad175a91 in gst_object_ref (object=0x126e8e0) at gstobject.c:327
#7  0x00002aaaad1a107e in gst_message_new_custom (type=GST_MESSAGE_ASYNC_DONE, src=0x126e8e0, structure=0x0) at gstmessage.c:292
#8  0x00002aaaad17b82e in bin_handle_async_done (bin=0x9e92c0, ret=GST_STATE_CHANGE_FAILURE) at gstbin.c:2533
#9  0x00002aaaad17c716 in gst_bin_handle_message_func (bin=0x126e8e0, message=0x1364340) at gstbin.c:2874
#10 0x00002aaaad1b3b75 in gst_pipeline_handle_message (bin=0x126e8e0, message=0x1364340) at gstpipeline.c:562
#11 0x00002aaaad17ab38 in bin_bus_handler (bus=<value optimized out>, message=0x1364340, bin=0x0) at gstbin.c:2394
#12 0x00002aaaad185715 in gst_bus_post (bus=0x1596430, message=0x1364340) at gstbus.c:349