[gst-devel] Gtype registration error

[Mattias Barthel]

Hello,

I am trying to get two of the same pipeline running in two separate 
threads (pthreads) in the same process.
I seem to have bumped into a kind of race condition.


This is what I get from the prompt:

(testlib:20311): GLib-GObject-WARNING **: cannot register existing type 
`GstClock'

(testlib:20311): GLib-GObject-WARNING **: gtype.c:3340: type id `0' is 
invalid

(testlib:20311): GLib-GObject-WARNING **: can't peek value table for 
type `<invalid>' which is not currently referenced

(testlib:20311): GLib-GObject-WARNING **: gvalue.c:96: cannot initialize 
GValue with type `(null)', this type has no GTypeValueTable implementation

(testlib:20311): GLib-GObject-WARNING **: gtype.c:3340: type id `0' is 
invalid

(testlib:20311): GLib-GObject-WARNING **: can't peek value table for 
type `<invalid>' which is not currently referenced
Fallo de segmentación (core dumped)


And the core file says:

Core was generated by `./testlib'.
Program terminated with signal 11, Segmentation fault.
#0  0xb7f4c1d6 in gst_structure_set_valist (structure=0x819fa28, 
fieldname=0xb7f783a4 "clock", varargs=0xb69c31b8 "") at gststructure.c:528
528         G_VALUE_COLLECT (&field.value, varargs, 0, &err);
(gdb) bt
#0  0xb7f4c1d6 in gst_structure_set_valist (structure=0x819fa28, 
fieldname=0xb7f783a4 "clock", varargs=0xb69c31b8 "") at gststructure.c:528
#1  0xb7f4e3be in gst_structure_new_valist (name=0xb7f7cf25 
"GstMessageClockProvide", firstfield=0xb7f783a4 "clock", 
varargs=0xb69c31b8 "") at gststructure.c:239
#2  0xb7f4e422 in gst_structure_new (name=0x0, firstfield=0xb7f783a4 
"clock") at gststructure.c:209
#3  0xb7f338bb in gst_message_new_clock_provide (src=0x80db6f0, 
clock=0x0, ready=1) at gstmessage.c:535
#4  0xb7f1138c in gst_bin_add_func (bin=0x80db600, element=0x80db6f0) at 
gstbin.c:906
#5  0xb7f0e4aa in gst_bin_add (bin=0x80db600, element=0x80db6f0) at 
gstbin.c:1038
#6  0xb7f5a79e in gst_bin_add_many (bin=0x80db600, element_1=0x80db6f0) 
at gstutils.c:2207
#7  0x0806889f in playerSimpleCreate (fP=0x80dc488, noPort1=0, 
noPort2=0, input=0x80dc5d8 "/home/demo/media/videos/toyota.mpg", 
bitrate=0, sourceType=0x80dc7e8 "filesrc",
  nada2=0) at playerSimple.c:416
#8  0x08056fe4 in flowPipelineCreate (flowP=0x80dc488) at vicoFlow.c:150
#9  0x0805733e in vicoFlowInit (flowP=0x80dc488) at vicoFlow.c:202
#10 0x0805634a in vicoRun (arg=0x80dc488) at vico.c:609
#11 0xb7cc046b in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#12 0xb7c446de in clone () from /lib/tls/i686/cmov/libc.so.6
(gdb)                                                                                            


I think this is because the two threads try too create their pipeline at 
the same time and Glibs hashtable of types does not reflect upon this. 
Or maybe there should be a mutex in
the gstreamer level?
So ifdeffing in the function check_type_name_I() in gtype.c the code the 
problem does not occur:
#if 0
if (g_type_from_name (type_name))
  {
    g_warning ("cannot register existing type `%s'", type_name);
    return FALSE;
  }
#endif


So whats the right way to go about this?
Does the gstreamer/glib framework really support mutlithreaded 
applications?ç

Thank you,

Mattias