diff --git a/trunk/research/st/srs.c b/trunk/research/st/srs.c
index aa6f60df0..77bccd159 100644
--- a/trunk/research/st/srs.c
+++ b/trunk/research/st/srs.c
@@ -5,10 +5,22 @@
 
 #define srs_trace(msg, ...)   printf(msg, ##__VA_ARGS__);printf("\n")
 
+st_cond_t cond = NULL;
+st_mutex_t mutex = NULL;
+
 void* pfn(void* arg)
 {
-    st_sleep(1);
-    srs_trace("st thread is ok");
+    st_usleep(100 * 1000);
+    st_cond_signal(cond);
+    
+    st_mutex_lock(mutex);
+    srs_trace("2. st mutex is ok");
+    st_mutex_unlock(mutex);
+    
+    st_usleep(100 * 1000);
+    srs_trace("3. st thread is ok");
+    st_cond_signal(cond);
+    
     return NULL;
 }
 
@@ -23,14 +35,40 @@ int main(int argc, char** argv)
         srs_trace("st_init failed");
         return -1;
     }
+
+    if ((cond = st_cond_new()) == NULL) {
+        srs_trace("st_cond_new failed");
+        return -1;
+    }
+    
+    if ((mutex = st_mutex_new()) == NULL) {
+        srs_trace("st_mutex_new failed");
+        return -1;
+    }
     
     if (!st_thread_create(pfn, NULL, 0, 0)) {
         srs_trace("st_thread_create failed");
         return -1;
     }
     
-    srs_trace("st is ok");
+    // lock mutex to control thread.
+    st_mutex_lock(mutex);
     
+    // wait thread to ready.
+    st_cond_wait(cond);
+    srs_trace("1. st cond is ok");
+    
+    // release mutex to control thread
+    st_usleep(100 * 1000);
+    st_mutex_unlock(mutex);
+    
+    // wait thread to exit.
+    st_cond_wait(cond);
+    srs_trace("4. st is ok");
+    
+    // cleanup.
+    st_cond_destroy(cond);
+    st_mutex_destroy(mutex);
     st_thread_exit(NULL);
     
     return 0;