[GitHub] [helix] kaisun2000 commented on a change in pull request #1066: Prevent parallel controller pipelines run causing two master replicas

[GitBox <gi...@apache.org>]

kaisun2000 commented on a change in pull request #1066:
URL: https://github.com/apache/helix/pull/1066#discussion_r465394923



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File path: helix-core/src/main/java/org/apache/helix/controller/GenericHelixController.java
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@@ -757,9 +753,20 @@ private void handleEvent(ClusterEvent event, BaseControllerDataProvider dataProv
     }
     event.addAttribute(AttributeName.ControllerDataProvider.name(), dataProvider);
 
-    logger.info(String.format("START: Invoking %s controller pipeline for cluster %s event: %s  %s",
-        manager.getClusterName(), dataProvider.getPipelineName(), event.getEventType(),
-        event.getEventId()));
+    // If manager session changes, no need to run pipeline for the stale event.
+    Optional<String> eventSessionId = event.getAttribute(AttributeName.EVENT_SESSION.name());
+    String managerSessionId = manager.getSessionId();

Review comment:
       If I understand correctly, the sessionId here can still be stale. eventually, we need sessionaware write of zkclient used by ZkHelixManager to ensure correctness, right?




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