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Posted to dev@pig.apache.org by "Thejas M Nair (JIRA)" <ji...@apache.org> on 2012/12/07 19:23:21 UTC

[jira] [Commented] (PIG-3044) Trigger POPartialAgg compaction under GC pressure

    [ https://issues.apache.org/jira/browse/PIG-3044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13526600#comment-13526600 ] 

Thejas M Nair commented on PIG-3044:
------------------------------------

bq. I would even say we remove the % memory budget as the Spillable mechanism is more reliable and much simpler.
The reason why % memory budget was introduced for SelfSpillBag, was because the spillable mechanism didn't always work well. The cleanup often was getting triggered too late. So I think it is better use the Spillable mechanism here to spill earlier if necessary, as the patch is doing.

                
> Trigger POPartialAgg compaction under GC pressure
> -------------------------------------------------
>
>                 Key: PIG-3044
>                 URL: https://issues.apache.org/jira/browse/PIG-3044
>             Project: Pig
>          Issue Type: Improvement
>    Affects Versions: 0.10.0, 0.11, 0.10.1
>            Reporter: Dmitriy V. Ryaboy
>            Assignee: Dmitriy V. Ryaboy
>             Fix For: 0.11, 0.12
>
>         Attachments: PIG-3044.2.diff, PIG-3404.diff
>
>
> If partial aggregation is turned on in pig 10 and 11, 20% (by default) of the available heap can be consumed by the POPartialAgg operator. This can cause memory issues for jobs that use all, or nearly all, of the heap already.
> If we make POPartialAgg "spillable" (trigger compaction when memory reduction is required), we would be much nicer to high-memory jobs.

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