[gstreamer-bugs] [Bug 566393] New: [deadlock] Setting index on a pipeline

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gstreamer (core) | Ver: HEAD CVS
           Summary: [deadlock] Setting index on a pipeline
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gstreamer (core)
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: bilboed at gmail.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


When setting a GstIndex on a pipeline containing index-aware elements, a
deadlock happens.

A simplified backtrace is the following (with flvdemux):
* gst_bin_set_index_func
* acquires the OBJECT_LOCK to iterate children
* calls set_index on child
* flv_demux_set_index asks for a writer id
* gstindex uses gst_object_get_path_string to calculate unique id
* gst_object_get_path tries to get the parent of flvdemux
==> DEADLOCK, the parent object lock was already acquired in
gst_bin_set_index_func


Full backtrace:
(gdb) bt
#0  0x00007f40ecee73f4 in __lll_lock_wait () from /lib/libpthread.so.0
#1  0x00007f40ecee2c50 in _L_lock_102 () from /lib/libpthread.so.0
#2  0x00007f40ecee255e in __pthread_mutex_lock (mutex=0xe27eb0) at
pthread_mutex_lock.c:86
#3  0x00007f40e993fb02 in gst_object_get_parent (object=0xd79040) at
gstobject.c:834
#4  0x00007f40e9940031 in gst_object_get_path_string (object=0xd79040) at
gstobject.c:1080
#5  0x00007f40e995f175 in gst_index_path_resolver (index=<value optimized out>,
writer=0x80, 
    writer_string=0x7f40eceea8e0, data=0xffffffffffffffff) at gstindex.c:626
#6  0x00007f40e995ed7d in gst_index_get_writer_id (index=0xd7a070,
writer=0xd740a0, id=0xd741a8)
    at gstindex.c:695
#7  0x00007f40e8685c7b in gst_flv_demux_set_index (element=0xd740a0,
index=0xd7a070) at gstflvdemux.c:1150
#8  0x00007f40e9947107 in gst_bin_set_index_func (element=<value optimized
out>, index=0xd7a070) at gstbin.c:635
#9  0x00007f40ea486a8f in _wrap_gst_element_set_index (self=0x87db40,
args=<value optimized out>, 
    kwargs=<value optimized out>) at gst.c:4496
#10 0x00007f40ed1a40d5 in PyEval_EvalFrameEx (f=0x61cc70, throwflag=<value
optimized out>) at Python/ceval.c:3573
#11 0x00007f40ed1a4f7d in PyEval_EvalCodeEx (co=0x7f40ed5dd468, globals=<value
optimized out>, 
    locals=<value optimized out>, args=0x0, argcount=0, kws=0x0, kwcount=0,
defs=0x0, defcount=0, closure=0x0)
    at Python/ceval.c:2836
#12 0x00007f40ed1a5097 in PyEval_EvalCode (co=0xe27eb0, globals=0x80,
locals=0x7f40eceea8e0)
    at Python/ceval.c:494
#13 0x00007f40ed1bd0dc in run_mod (mod=<value optimized out>, filename=<value
optimized out>, globals=0x6254f0, 
    locals=0x6254f0, flags=<value optimized out>, arena=<value optimized out>)
at Python/pythonrun.c:1273
#14 0x00007f40ed1bd18c in PyRun_FileExFlags (fp=0x602010,
filename=0x7ffff5669279 "./index1.py", 
    start=<value optimized out>, globals=0x6254f0, locals=0x6254f0, closeit=1,
flags=0x7ffff56684b0)
    at Python/pythonrun.c:1259
#15 0x00007f40ed1be56b in PyRun_SimpleFileExFlags (fp=0x602010,
filename=0x7ffff5669279 "./index1.py", 
    closeit=1, flags=0x7ffff56684b0) at Python/pythonrun.c:879
#16 0x00007f40ed1c6c62 in Py_Main (argc=2, argv=0x7ffff56685c8) at
Modules/main.c:523
#17 0x00007f40ec519486 in __libc_start_main (main=0x400828 <main>, argc=3,
ubp_av=0x7ffff56685c8, 
    init=0x400840 <__libc_csu_init>, fini=<value optimized out>,
rtld_fini=<value optimized out>, 
    stack_end=0x7ffff56685b8) at libc-start.c:226
#18 0x0000000000400789 in _start ()
Current language:  auto; currently asm


Simple python script to trigger the above:

p = gst.parse_launch("filesrc ! flvdemux ! fakesink")
i = gst.index_factory_make("memindex")
print "Before setting index"
p.set_index(i)
print "After setting index"


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