diff --git a/trunk/src/app/srs_app_conn.hpp b/trunk/src/app/srs_app_conn.hpp
index db10ee423..ac95ca52d 100644
--- a/trunk/src/app/srs_app_conn.hpp
+++ b/trunk/src/app/srs_app_conn.hpp
@@ -47,8 +47,11 @@ public:
     virtual ~ISrsDisposingHandler();
 public:
     // When before disposing resource, trigger when manager.remove(c), sync API.
+    // @remark Recommend to unref c, after this, no other objects refs to c.
     virtual void on_before_dispose(ISrsResource* c) = 0;
     // When disposing resource, async API, c is freed after it.
+    // @remark Recommend to stop any thread/timer of c, after this, fields of c is able
+    // to be deleted in any order.
     virtual void on_disposing(ISrsResource* c) = 0;
 };
 
diff --git a/trunk/src/app/srs_app_st.cpp b/trunk/src/app/srs_app_st.cpp
index 5a1954a4b..9985f2b44 100755
--- a/trunk/src/app/srs_app_st.cpp
+++ b/trunk/src/app/srs_app_st.cpp
@@ -207,13 +207,14 @@ srs_error_t SrsFastCoroutine::start()
 void SrsFastCoroutine::stop()
 {
     if (disposed) {
+        // TODO: FIXME: If previous stop is wait on st_thread_join, this call should assert fail.
         return;
     }
     disposed = true;
     
     interrupt();
 
-    // When not started, the rd is NULL.
+    // When not started, the trd is NULL.
     if (trd) {
         void* res = NULL;
         int r0 = st_thread_join((st_thread_t)trd, &res);
@@ -245,7 +246,9 @@ void SrsFastCoroutine::interrupt()
     if (trd_err == srs_success) {
         trd_err = srs_error_new(ERROR_THREAD_INTERRUPED, "interrupted");
     }
-    
+
+    // Note that if another thread is stopping thread and waiting in st_thread_join,
+    // the interrupt will make the st_thread_join fail.
     st_thread_interrupt((st_thread_t)trd);
 }