[jira] [Updated] (HIVE-15221) Improvement for MapJoin checkMemoryStatus, adding gc before throwing Exception

["Fei Hui (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-15221?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Fei Hui updated HIVE-15221:
---------------------------
    Status: Patch Available  (was: Open)

> Improvement for MapJoin checkMemoryStatus, adding gc before throwing Exception
> ------------------------------------------------------------------------------
>
>                 Key: HIVE-15221
>                 URL: https://issues.apache.org/jira/browse/HIVE-15221
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>    Affects Versions: 2.0.1, 2.1.0
>            Reporter: Fei Hui
>            Assignee: Fei Hui
>         Attachments: HIVE-15221.1.patch
>
>
> i see in the current master version
>  percentage = (double) usedMemory / (double) maxHeapSize;
> if  percentage > maxMemoryUsage, then throw MapJoinMemoryExhaustionException
> in my opinion, running is better than fail. after System.gc, ' if percentage > maxMemoryUsage, then throw MapJoinMemoryExhaustionException' maybe better
> And original checking way has a problem: 1) consuming much memory cause gc (e.g young gc), then check after adding row and pass. 2) consuming much memory does not cause gc, then check after adding rows but throw Exception
> sometimes 2) occurs, but it contians less rows than 1).



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