Crashes on gst_bus_add_watch

[Duzy Chan]

And here are some CRITICAL warnings:

  GStreamer-CRITICAL **: gst_poll_get_read_gpollfd: assertion `set != NULL'
failed
  GStreamer-CRITICAL **: gst_bus_create_watch: assertion `bus->priv->poll
!= NULL' failed
  GLib-CRITICAL **: g_source_set_callback: assertion `source != NULL' failed




On Fri, Jan 25, 2013 at 7:09 PM, Duzy Chan <geek at duzy.info> wrote:

> The worker in this case is wrapping a pipeline and watching the bus of the
> pipeline. And the crash was happened while creating the worker and
> preparing for further usage.
>
> While repeatedly creating many workers and each worker may exist only for
> a short time (maybe less than 1 second), and then be stopped
> (gst_element_set_state to null state), and then unref (including the
> pipeline). After repeat for a while, the problem occurs.
>
>
> On Fri, Jan 25, 2013 at 5:44 PM, Duzy Chan <geek at duzy.info> wrote:
>
>> Greeting, all
>>
>> I'm currently working on a app. But I'm now confronting a crash
>> while repeatedly creating a pipeline very quickly. And I found that it was
>> caused by a gst_bus_add_watch (http://pastebin.com/b2DVmHnQ). The code
>> in *gst_bus_add_watch_full_unlocked* was trying to creating a new
>> GSource by calling *gst_bus_create_watch*, yet it turned out a NULL
>> source. This is the final end point of the cause. And the code in *
>> gstbus.c* looks like this:
>>
>> static guint
>> *gst_bus_add_watch_full_unlocked* (GstBus * bus, gint priority,
>>     GstBusFunc func, gpointer user_data, GDestroyNotify notify)
>> {
>>   GMainContext *ctx;
>>   guint id;
>>   GSource *source;
>>
>>   if (bus->priv->watch_id) {
>>     GST_ERROR_OBJECT (bus,
>>         "Tried to add new watch while one was already there");
>>     return 0;
>>   }
>>
>>   *source* = *gst_bus_create_watch* (bus);
>>
>>   if (priority != G_PRIORITY_DEFAULT)
>>     g_source_set_priority (*source*, priority);
>>
>>   g_source_set_callback (*source*, (GSourceFunc) func, user_data,
>> notify);
>>
>>   ctx = g_main_context_get_thread_default ();
>>   id = g_source_attach (source, ctx);
>>   g_source_unref (source);
>>
>>   if (id) {
>>     bus->priv->watch_id = source;
>>   }
>>
>>   GST_DEBUG_OBJECT (bus, "New source %p with id %u", source, id);
>>   return id;
>> }
>>
>>
>> And the client code from my app looks like this:
>>
>>   worker->pipeline = workerclass->create_pipeline (worker);
>>   if (!worker->pipeline)
>>     goto error_create_pipeline;
>>
>>   gst_pipeline_set_auto_flush_bus (GST_PIPELINE (worker->pipeline),
>> FALSE);
>>
>>   worker->bus = gst_pipeline_get_bus (GST_PIPELINE (worker->pipeline));
>>   worker->watch = *gst_bus_add_watch* (worker->bus, gst_worker_message,
>> worker);
>>
>>
>> Part of the stack when it crashed is like this:
>>
>> #0  0x00007ffff728ef56 in *g_source_attach* () from
>> /lib/x86_64-linux-gnu/libglib-2.0.so.0
>> #1  0x00007ffff7b1e228 in *gst_bus_add_watch_full_unlocked*(notify=<optimized out>, user_data=0x7fffc801a0c0, func=0x403d50
>> <gst_worker_message>, priority=<optimized out>, bus=<optimized out>) at
>> gstbus.c:867
>> #2  gst_bus_add_watch_full_unlocked (bus=<optimized out>,
>> priority=<optimized out>, func=0x403d50 <gst_worker_message>,
>> user_data=0x7fffc801a0c0, notify=<optimized out>) at gstbus.c:846
>> #3  0x00007ffff7b1e367 in gst_bus_add_watch_full (bus=0x991c10,
>> priority=priority at entry=0, func=func at entry=0x403d50
>> <gst_worker_message>, user_data=user_data at entry=0x7fffc801a0c0,
>> notify=notify at entry=0x0) at gstbus.c:916
>> #4  0x00007ffff7b1e390 in *gst_bus_add_watch* (bus=<optimized out>,
>> func=func at entry=0x403d50 <gst_worker_message>, user_data=user_data at entry=0x7fffc801a0c0)
>> at gstbus.c:948
>> #5  0x00000000004041b1 in gst_worker_prepare (worker=0x7fffc801a0c0) at
>> gstworker.c:480
>>
>>
>> Do you have any ideas about this? I've been tracking on it for long time,
>> still have no lucks.
>>
>> Regards
>> Duzy Chan
>>
>>
>
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