[gstreamer-bugs] [Bug 579416] New: Nasty gst-python deadlock

Sat Apr 18 07:35:30 PDT 2009

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  GStreamer | gst-python | Ver: git
           Summary: Nasty gst-python deadlock
           Product: GStreamer
           Version: git
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: gst-python
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: thaytan at mad.scientist.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified

Just encountered this nasty deadlock with gst-python and Thomas' jukebox code.
It looks like one thread is calling gst_object_get_parent (holding the object
lock), which triggers a toggle_refs_notify into Python code. In another thread,
Python is trying to call gst_object_get_name() on the same object, while
holding the Python lock.

Patch coming...

Thread 2 (Thread 0xb7c92b70 (LWP 16763)):
#0  0x00549424 in __kernel_vsyscall ()
#1  0x00bd02e5 in sem_wait@@GLIBC_2.1 ()
    at ../nptl/sysdeps/unix/sysv/linux/i386/i486/sem_wait.S:80
#2  0x0397e668 in PyThread_acquire_lock (lock=0x9487550, waitflag=1)
    at Python/thread_pthread.h:349
#3  0x03957008 in PyEval_RestoreThread (tstate=0xb7103a38)
    at Python/ceval.c:334
#4  0x039715c3 in PyGILState_Ensure () at Python/pystate.c:592
#5  0x0078ab69 in pyglib_gil_state_ensure () from /usr/lib/libpyglib-2.0.so.0
#6  0x0064961f in ?? ()
   from /usr/lib/python2.6/site-packages/gtk-2.0/gobject/_gobject.so
#7  0x00d0d36b in toggle_refs_notify (object=<value optimized out>, 
    is_last_ref=0) at gobject.c:2192
#8  0x00d0d6e7 in IA__g_object_ref (_object=0x94ca038) at gobject.c:2351
#9  0x0038662d in gst_object_ref (object=0x94ca038) at gstobject.c:299
#10 0x00386d42 in gst_object_get_parent (object=0x94cd068) at gstobject.c:805
#11 0x00388220 in gst_object_dispatch_properties_changed (object=0x9507488, 
    n_pspecs=1, pspecs=0xb7c91870) at gstobject.c:499
#12 0x00d0c0df in g_object_notify_dispatcher (object=0x9507488, n_pspecs=1, 
    pspecs=0xb7c91870) at gobject.c:312
#13 0x00d111f3 in g_object_notify_queue_thaw (nqueue=<value optimized out>, 
    object=<value optimized out>) at gobjectnotifyqueue.c:125
#14 IA__g_object_notify (nqueue=<value optimized out>, 
    object=<value optimized out>) at gobject.c:857
#15 0x003b823b in gst_pad_set_caps (pad=0x9507488, caps=0x932aba0)
    at gstpad.c:2519
#16 0x003b8d64 in gst_pad_configure_sink (pad=0x9507488, caps=0x932aba0)
    at gstpad.c:2560
#17 0x003b8faa in gst_pad_chain_unchecked (pad=0x9507488, 
    buffer=<value optimized out>) at gstpad.c:3962
#18 0x003ba1fa in gst_pad_push (pad=0x94d5700, buffer=0x94de668)
    at gstpad.c:4144
#19 0x00f0984d in gst_mp3parse_emit_frame (mp3parse=0x95065f0, size=417, 
    mode=1, crc=0) at gstmpegaudioparse.c:835
#20 0x00f0b820 in gst_mp3parse_chain (pad=0x94d5640, buf=0x9516948)
    at gstmpegaudioparse.c:1349
#21 0x003b8ecb in gst_pad_chain_unchecked (pad=0x94d5640, 
    buffer=<value optimized out>) at gstpad.c:3977
#22 0x003ba1fa in gst_pad_push (pad=0x94d5580, buffer=0x9516948)
    at gstpad.c:4144
#23 0x0024f1c7 in gst_tag_demux_chain (pad=0x94d54c0, buf=0x9516948)
    at gsttagdemux.c:692
#24 0x003b8ecb in gst_pad_chain_unchecked (pad=0x94d54c0, 
    buffer=<value optimized out>) at gstpad.c:3977
#25 0x003ba1fa in gst_pad_push (pad=0x94d5400, buffer=0x9516948)
    at gstpad.c:4144
#26 0x00deacf7 in gst_type_find_element_chain (pad=0x94d5340, buffer=0x9516948)
    at gsttypefindelement.c:688
#27 0x003b8ecb in gst_pad_chain_unchecked (pad=0x94d5340, 
    buffer=<value optimized out>) at gstpad.c:3977
---Type <return> to continue, or q <return> to quit---
#28 0x003ba1fa in gst_pad_push (pad=0x94e5038, buffer=0x9516948)
    at gstpad.c:4144
#29 0x003a994d in gst_proxy_pad_do_chain (pad=0x94e4800, buffer=0x9516948)
    at gstghostpad.c:193
#30 0x003b8ecb in gst_pad_chain_unchecked (pad=0x94e4800, 
    buffer=<value optimized out>) at gstpad.c:3977
#31 0x003ba1fa in gst_pad_push (pad=0x94d5280, buffer=0x9516948)
    at gstpad.c:4144
#32 0x001f7236 in gst_base_src_loop (pad=0x94d5280) at gstbasesrc.c:2279
#33 0x003dd9fd in gst_task_func (task=0x94f1ae8, tclass=0x9219448)
    at gsttask.c:172
#34 0x00c822cf in g_thread_pool_thread_proxy (data=0x92194d8)
    at gthreadpool.c:265
#35 0x00c80c7f in g_thread_create_proxy (data=0x9328fd8) at gthread.c:635
#36 0x00bc9965 in start_thread (arg=0xb7c92b70) at pthread_create.c:297
#37 0x00afdfee in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 1 (Thread 0xb80836c0 (LWP 16761)):
#0  0x00549424 in __kernel_vsyscall ()
#1  0x00bd0bd9 in __lll_lock_wait ()
    at ../nptl/sysdeps/unix/sysv/linux/i386/i486/lowlevellock.S:142
#2  0x00bcbf1b in _L_lock_752 () from /lib/libpthread.so.0
#3  0x00bcbd31 in __pthread_mutex_lock (mutex=0x93363b0)
    at pthread_mutex_lock.c:61
#4  0x003872b3 in gst_object_get_name (object=0x94cd068) at gstobject.c:670
#5  0x001b9ad2 in ?? ()
   from /usr/lib/python2.6/site-packages/gst-0.10/gst/_gst.so
#6  0x038fb8d5 in PyObject_Repr (v=0xb8043d28) at Objects/object.c:366
#7  0x0390bc10 in PyString_Format (format=0xb8025d40, args=0x944512c)
    at Objects/stringobject.c:4851
#8  0x0390cdbf in string_mod (v=0xfffffe00, w=0x944512c)
    at Objects/stringobject.c:4116
#9  0x038b8fa3 in binary_op1 (v=0xb8025d40, w=0x944512c, op_slot=16)
    at Objects/abstract.c:914
#10 0x038b9afb in binary_op (v=0xb8025d40, w=0x93363b0, op_slot=16, 
    op_name=0x3999062 "%") at Objects/abstract.c:966
#11 0x03951a56 in PyEval_EvalFrameEx (f=0x9197e1c, throwflag=0)
    at Python/ceval.c:1152
#12 0x03955fa1 in fast_function (nk=<value optimized out>, 
    na=<value optimized out>, n=<value optimized out>, 
    pp_stack=<value optimized out>, func=<value optimized out>)
    at Python/ceval.c:3765
#13 call_function (nk=<value optimized out>, na=<value optimized out>, 
    n=<value optimized out>, pp_stack=<value optimized out>, 
    func=<value optimized out>) at Python/ceval.c:3700
#14 PyEval_EvalFrameEx (nk=<value optimized out>, na=<value optimized out>, 
    n=<value optimized out>, pp_stack=<value optimized out>, 
    func=<value optimized out>) at Python/ceval.c:2370
#15 0x03956e21 in PyEval_EvalCodeEx (co=0xb8070458, globals=0xb806702c, 
    locals=0xb806702c, args=0x0, argcount=0, kws=0x0, kwcount=0, defs=0x0, 
    defcount=0, closure=0x0) at Python/ceval.c:2942
#16 0x03956f83 in PyEval_EvalCode (co=0xb8070458, globals=0xb806702c,

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