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https://issues.apache.org/jira/browse/MAPREDUCE-5329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13695601#comment-13695601
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Siddharth Seth commented on MAPREDUCE-5329:
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bq. serviceData.put(serviceName, 
ShuffleHandler.serializeServiceData(shuffleToken));
Shouldn't this be specific to the shuffle provider ?

Also the alternate provider also works with a single shuffle port and makes use 
of job tokens, correct ? Shuffle port being ingrained in several places in the 
AM makes this a tough change for other types of providers.

I believe you want to fall back to a different shuffle provider if one does not 
work. I assume they're running on different ports - am not sure the fallback 
will work in that case. 

ContainerLauncherImpl likely needs some change as well - since the 
startContainer response contains service data set by the specific provider, and 
is deserialized in the AM to figure out the shuffle port. If you use a provider 
other than the default ShuffleHandler - the port should be read based on that 
providers service id.

bq.  Based on your request, I created YARN-886 make APPLICATION_STOP consistent 
with APPLICATION_INIT
Thanks
                
> 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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