[ISSUE #10990] Skip pop retry arrival notification when properties are null

broker/src/main/java/org/apache/rocketmq/broker/longpolling/PopLongPollingService.java

@@ -180,6 +180,12 @@ public void notifyMessageArrivingWithRetryTopic(final String topic, final int qu
 
     private void notifyMessageArrivingFromRetry(String topic, int queueId, Long tagsCode, long msgStoreTime, byte[] filterBitMap,
         Map<String, String> properties) {
+        if (properties == null) {
+            // A retry topic message without properties can't be mapped back to its origin group,
+            // so there is no long polling request to wake up. Throwing here would poison the
+            // reput thread for every following message.
+            return;
+        }
         String prefix = MixAll.RETRY_GROUP_TOPIC_PREFIX;
         String originGroup = properties.get(MessageConst.PROPERTY_ORIGIN_GROUP);
         // In the case of pop consumption, there is no long polling hanging on the retry topic, so the wake-up is skipped.

broker/src/test/java/org/apache/rocketmq/broker/longpolling/PopLongPollingServiceTest.java

@@ -47,8 +47,13 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -110,6 +115,19 @@ public void testNotifyMessageArrivingFromRetry() {
         verify(popLongPollingService, times(2)).notifyMessageArriving(defaultTopic, queueId, group, true, -1L, 0L, null, properties, null);
     }
 
+    @Test
+    public void testNotifyMessageArrivingFromRetryWithoutProperties() {
+        int queueId = -1;
+        String group = "group";
+        String pullRetryTopic = MixAll.getRetryTopic(group);
+        // A message stored on a retry topic without any properties (properties map is null,
+        // e.g. written by a non-Java client) must not throw, otherwise the reput thread
+        // stalls dispatch of every following message.
+        popLongPollingService.notifyMessageArrivingWithRetryTopic(pullRetryTopic, queueId, queueId, -1L, 0L, null, null);
+        verify(popLongPollingService, never()).notifyMessageArriving(anyString(), anyInt(), anyString(), anyBoolean(),
+            any(), anyLong(), any(), any(), any());
+    }
+
     @Test
     public void testNotifyMessageArriving() {
         int queueId = 0;