try to fix reader and signal test failed (#30960)

paddle/fluid/operators/reader/reader_blocking_queue_test.cc

@@ -68,7 +68,7 @@ TEST(BlockingQueue, SenderBlockingTest) {
       ++send_count;
     }
   });
-  std::this_thread::sleep_for(std::chrono::milliseconds(200));
+  std::this_thread::sleep_for(std::chrono::milliseconds(1000));
   q.Close();
   sender.join();
   EXPECT_EQ(send_count, queue_cap);

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

@@ -70,16 +70,26 @@ class TestDygraphDataLoaderSingalHandler(unittest.TestCase):
             core._set_process_signal_handler()
             os.kill(os.getpid(), signal.SIGSEGV)
 
+        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("Segmentation fault", cpt.get_exception_message(ex))
+                self.assertIn("Segmentation fault",
+                              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)
 
@@ -88,16 +98,25 @@ class TestDygraphDataLoaderSingalHandler(unittest.TestCase):
             core._set_process_signal_handler()
             os.kill(os.getpid(), signal.SIGBUS)
 
+        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("Bus error", 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)