add a ctest hung tool

Author: yi.wu

python/paddle/fluid/tests/unittests/test_listen_and_serv_op.py

@@ -92,13 +92,15 @@ def test_handle_signal_in_serv_op(self):
         pid = self._start_pserver(False, True)
         self._wait_ps_ready(pid)
 
+        print("send kill signal, ", pid)
         # raise SIGTERM to pserver
         os.kill(pid, signal.SIGTERM)
 
         # run pserver on CPU in async mode
         pid = self._start_pserver(False, False)
         self._wait_ps_ready(pid)
 
+        print("send kill signal, ", pid)
         # raise SIGTERM to pserver
         os.kill(pid, signal.SIGTERM)