[gst-devel] Possible bug in subparse

[KwangYul Seo]

Hello,

I compiled subparse and pango in Windows and found a race condition in
subparse. In Windows, subparse module crashed immediately, but when I put  a
g_usleep before get_pad_push(self->srcpad, buf) in handler_buffer() function
of gstsubparse.c, it works fine.

In gstsubparse.c:

static GstFlowReturn
handle_buffer (GstSubParse * self, GstBuffer * buf)
{
    ...
        g_usleep(1000 * 1000);  /* I put sleep here */
        ret = gst_pad_push (self->srcpad, buf);
    ....
}

I don't need to call g_usleep everytime, but only for the first time after
the player is launched. The following code still works.

static GstFlowReturn
handle_buffer (GstSubParse * self, GstBuffer * buf)
{
   static int init = 0;
    ...

        if (init ==0) { /* Put sleep only for the first time */
            g_usleep(1000 * 1000);
            init = 1;
        }
        ret = gst_pad_push (self->srcpad, buf);
    ....
}


I guess there might be a subtle race condition bug in subparse or pango
module. However, I failed to find the scenario how this happened. Is this a
known issue?

The following is the stack trace from MSVC.

>    libgstplaybin.dll!00e53e37()
     libgstplaybin.dll!00e53d70()
     libgobject-2.0-0.dll!62743995()
     msvcrt.dll!77bdc774()
     libglib-2.0-0.dll!672d2449()
     libgobject-2.0-0.dll!62757195()
     libglib-2.0-0.dll!672e52c5()
     libgobject-2.0-0.dll!62747534()
     libgobject-2.0-0.dll!6276388a()
     libgobject-2.0-0.dll!62757f3e()
     ntdll.dll!7c940732()
     ntdll.dll!7c9406ab()
     libgthread-2.0-0.dll!64941273()
     libglib-2.0-0.dll!672fe47e()
     libgobject-2.0-0.dll!6275bfe3()
     ntdll.dll!7c9406eb()
     libgthread-2.0-0.dll!64941b67()
     msvcrt.dll!77bdc3ce()
     libgthread-2.0-0.dll!64941b67()
     libglib-2.0-0.dll!672f7045()
     libgthread-2.0-0.dll!649412b3()
     libgstreamer-0.10.dll!003b0f10()
     libgstreamer-0.10.dll!003b0f2b()
     libgobject-2.0-0.dll!6274773b()
     libgstreamer-0.10.dll!00399306()
     libgobject-2.0-0.dll!6275cc54()
     ntdll.dll!7c9406eb()
     msvcrt.dll!77bdc3c9()
     msvcrt.dll!77bdc3ce()
     msvcrt.dll!77bdc3ce()
     libgobject-2.0-0.dll!6274773b()
     libgstcoreelements.dll!00e7a980()
     libgobject-2.0-0.dll!627581b6()
     libgstcoreelements.dll!00e7a9c3()
     libgstreamer-0.10.dll!003b25ba()
     libgstplaybin.dll!00e58d6c()
     libgstreamer-0.10.dll!003b25ba()
     libgstreamer-0.10.dll!003a7225()
     libgstreamer-0.10.dll!003b25ba()
     libgstsubparse.dll!00df2b7c()
     libgstsubparse.dll!00df26db()
     libgstreamer-0.10.dll!003b25ba()
     libgstcoreelements.dll!00e7e58a()
     libgstreamer-0.10.dll!003b25ba()
     libgstreamer-0.10.dll!003a7225()
     libgstreamer-0.10.dll!003b25ba()
     libgstbase-0.10.dll!00eaa006()
     libgstreamer-0.10.dll!003c0959()
     ntdll.dll!7c940551()
     libglib-2.0-0.dll!672ff21a()
     ntdll.dll!7c940551()
     libgthread-2.0-0.dll!64941b42()
     ntdll.dll!7c940551()
     libglib-2.0-0.dll!672fd775()
     ntdll.dll!7c940551()
     libgthread-2.0-0.dll!649420da()
     msvcrt.dll!77bea3b0()
     ntdll.dll!7c940551()
     kernel32.dll!7c80b683()
     ntdll.dll!7c940551()

Thanks,
Kwang Yul Seo
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