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https://issues.apache.org/jira/browse/MAPREDUCE-5329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13686322#comment-13686322
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Siddharth Seth commented on MAPREDUCE-5329:
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This could end up being a complicated change depending on the kind of
configuration information required by your providers / consumers. Does your
custom shuffle handler have a port as the service data ? That's ingrained into
the MR AM and tasks. See ContainerLauncherImpl. In this case it may not be too
complicated.
This will likely need additional config parameters to configure the list of aux
services being used, along with their service IDs. TaskAttemptImpl will also
need change.
> APPLICATION_INIT is never sent to AuxServices other than the builtin
> ShuffleHandler
> -----------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5329
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5329
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mr-am
> Affects Versions: 2.0.4-alpha
> Reporter: Avner BenHanoch
>
> 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|http://hadoop.apache.org/docs/current/hadoop-mapreduce-client/hadoop-mapreduce-client-core/PluggableShuffleAndPluggableSort.html]
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