Hi Vinayak,
Looking at the code, here are a couple notes:
1. Instantiating your own GenericHelixController is unnecessary as the Helix
manager already does this.2. Even considering #1, you're right: there are still
repeat callbacks.
Here are the tracebacks I generated: https://gist.github.com/kanakb/8639730
The sequence is:
1. ZKHelixManager#handleNewSession() calls handleNewSessionAsController()1.
handleNewSessionAsController adds a controller callback for leader election2.
CallbackHandler calls init on that controller callback3. The controller
callback adds all other callbacks, resulting in init being called for each4.
ZKHelixManager#handleNewSession calls initHandlers()5. initHandlers() iterates
over all currently registered callbacks and calls init() on them6.
CallbackHandler knows it's already received an init, so it simply returns
without doing anything on those callbacks
So yes, we do have repeat callback initializations for the controller and it
should be possible to avoid the double inits. These are, however, harmless and
inexpensive.
Kanak
> Date: Sun, 26 Jan 2014 12:13:16 -0800
> From: [email protected]
> To: [email protected]
> Subject: Duplicate INIT in Controller
>
> Hi,
>
> I am observing duplicate handlers being added to the controller and this
> is leading to INIT being called multiple times on the same handlers.
>
> Here is my code to start the controler, which looks fairly standard:
>
> @Override
> protected void doStart() throws SystemException {
> hManager = HelixManagerFactory.getZKHelixManager(clusterName,
> UUID.randomUUID().toString(),
> InstanceType.CONTROLLER, zkAddr);
> try {
> hManager.connect();
> } catch (Exception e) {
> throw new SystemException(e);
> }
> GenericHelixController controller = new GenericHelixController();
> HelixControllerMain.addListenersToController(hManager, controller);
> }
>
>
>
> Here are the log messages due to duplicate calls:
>
> 2014-01-26 12:11:16,721 WARN [CallbackHandler] Skip processing
> callbacks for listener:
> org.apache.helix.messaging.handling.HelixTaskExecutor@7f3076b2, path:
> /e78dead7-0c2f-4c5f-af7e-f25e8c170db1/CONTROLLER/MESSAGES, expected
> types: [CALLBACK, FINALIZE] but was INIT
> 2014-01-26 12:11:16,721 WARN [CallbackHandler] Skip processing
> callbacks for listener:
> org.apache.helix.controller.GenericHelixController@4db4bfda, path:
> /e78dead7-0c2f-4c5f-af7e-f25e8c170db1/CONFIGS/PARTICIPANT, expected
> types: [CALLBACK, FINALIZE] but was INIT
> 2014-01-26 12:11:16,721 WARN [CallbackHandler] Skip processing
> callbacks for listener:
> org.apache.helix.controller.GenericHelixController@4db4bfda, path:
> /e78dead7-0c2f-4c5f-af7e-f25e8c170db1/LIVEINSTANCES, expected types:
> [CALLBACK, FINALIZE] but was INIT
> 2014-01-26 12:11:16,721 WARN [CallbackHandler] Skip processing
> callbacks for listener:
> org.apache.helix.controller.GenericHelixController@4db4bfda, path:
> /e78dead7-0c2f-4c5f-af7e-f25e8c170db1/IDEALSTATES, expected types:
> [CALLBACK, FINALIZE] but was INIT
> 2014-01-26 12:11:16,721 WARN [CallbackHandler] Skip processing
> callbacks for listener:
> org.apache.helix.controller.GenericHelixController@4db4bfda, path:
> /e78dead7-0c2f-4c5f-af7e-f25e8c170db1/CONTROLLER, expected types:
> [CALLBACK, FINALIZE] but was INIT
>
>
> Thanks,
> Vinayak
