[MAPREDUCE-5329] APPLICATION_INIT is never sent to AuxServices other than the builtin ShuffleHandler

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.1.0-beta, 2.0.6-alpha
• Fix Version/s: 2.3.0
• Component/s: mr-am
• Target Version/s: 2.1.1-beta, 2.2.0, 2.3.0
• Hadoop Flags: Reviewed
• Assignee: Avner BenHanoch
• Reporter: Avner BenHanoch
• Created: 13/Jun/13 14:37
• Updated: 10/Mar/15 04:30
• Resolved: 13/Oct/13 20:20

Description

APPLICATION_INIT is never sent to AuxServices other than the built-in ShuffleHandler. This means that 3rd party ShuffleProvider(s) will not be able to function, because APPLICATION_INIT enables the AuxiliaryService to map jobId->userId. This is needed for properly finding the MOFs of a job per reducers' requests.

NOTE: The built-in ShuffleHandler does get APPLICATION_INIT events due to hard-coded expression in hadoop code. The current TaskAttemptImpl.java code explicitly call: serviceData.put (ShuffleHandler.MAPREDUCE_SHUFFLE_SERVICEID, ...) and ignores any additional AuxiliaryService. As a result, only the built-in ShuffleHandler will get APPLICATION_INIT events. Any 3rd party AuxillaryService will never get APPLICATION_INIT events.

I think a solution can be in one of two ways:
1. Change TaskAttemptImpl.java to loop on all Auxiliary Services and register each of them, by calling serviceData.put (…) in loop.
2. Change AuxServices.java similar to the fix in: MAPREDUCE-2668 "APPLICATION_STOP is never sent to AuxServices". This means that in case the 'handle' method gets APPLICATION_INIT event it will demultiplex it to all Aux Services regardless of the value in event.getServiceID().

I prefer the 2nd solution. I am welcoming any ideas. I can provide the needed patch for any option that people like.

See Pluggable Shuffle in Hadoop documentation

Issue Links

• relates to: MAPREDUCE-4049 plugin for generic shuffle service
• relates to: YARN-841 Annotate and document AuxService APIs
• relates to: YARN-886 make APPLICATION_STOP consistent with APPLICATION_INIT
• relates to: MAPREDUCE-2668 MR-279: APPLICATION_STOP is never sent to AuxServices