[infinispan-issues] [JBoss JIRA] (ISPN-4022) M/R: Run the combiner concurrently with the mapper

[Dan Berindei (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-4022?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12949617#comment-12949617 ] 

Dan Berindei commented on ISPN-4022:
------------------------------------

+1. Shipping the intermediate values to the reducer node after each chunk is produced should help even without a combiner.
                
> M/R: Run the combiner concurrently with the mapper
> --------------------------------------------------
>
>                 Key: ISPN-4022
>                 URL: https://issues.jboss.org/browse/ISPN-4022
>             Project: Infinispan
>          Issue Type: Feature Request
>          Components: Core, Distributed Execution and Map/Reduce
>    Affects Versions: 6.0.1.Final
>            Reporter: Dan Berindei
>            Assignee: Vladimir Blagojevic
>             Fix For: 7.0.0.Final
>
>
> Because we only run the combiner after we finished the mapping phase, we need to keep all the results of the mapping phase in memory at once. We should split the output of the mapper into chunks and allow the combiner to process chunks while the mapper is still running, relieving some of the memory pressure. Maybe even block the mapper if there are too many chunks in-flight.

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