merge from srs2

@@ -1288,6 +1288,7 @@ Winlin
 [bug #511]: https://github.com/ossrs/srs/issues/511
 [bug #518]: https://github.com/ossrs/srs/issues/518
 [bug #541]: https://github.com/ossrs/srs/issues/541
+[bug #546]: https://github.com/ossrs/srs/issues/546
 [bug #xxxxxxxxxx]: https://github.com/ossrs/srs/issues/xxxxxxxxxx
 
 [exo #828]: https://github.com/google/ExoPlayer/pull/828

@@ -237,11 +237,13 @@ namespace internal
         // readly terminated now.
         really_terminated = true;
         
-        handler->on_thread_stop();
-        srs_info("thread %s cycle finished", _name);
-        
         // when thread terminated normally, also disposed.
+        // we must set to disposed before the on_thread_stop, which may free the thread.
+        // @see https://github.com/ossrs/srs/issues/546
         disposed = true;
+        
+        handler->on_thread_stop();
+        srs_info("thread %s cycle finished", _name);
     }
     
     void* SrsThread::thread_fun(void* arg)