try multi times for sys.exit (#30188)

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

@@ -41,18 +41,27 @@ class TestDygraphDataLoaderSingalHandler(unittest.TestCase):
     def test_child_process_exit_with_error(self):
         def __test_process__():
             core._set_process_signal_handler()
-            os._exit(os.EX_DATAERR)
+            sys.exit(1)
 
+        def try_except_exit():
             exception = None
             try:
                 test_process = multiprocessing.Process(target=__test_process__)
                 test_process.start()
 
                 set_child_signal_handler(id(self), test_process.pid)
-            time.sleep(10)
+                time.sleep(5)
             except SystemError as ex:
                 self.assertIn("Fatal", cpt.get_exception_message(ex))
                 exception = ex
+            return exception
+
+        try_time = 10
+        exception = None
+        for i in range(try_time):
+            exception = try_except_exit()
+            if exception is not None:
+                break
 
         self.assertIsNotNone(exception)