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From "Paul Rogers (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-5210) External Sort BatchGroup leaks memory if an OOM occurs during read
Date Wed, 22 Feb 2017 01:34:44 GMT

    [ https://issues.apache.org/jira/browse/DRILL-5210?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15877222#comment-15877222

Paul Rogers commented on DRILL-5210:

Tested using the fault injector mechanism. Memory is now properly managed and released; no
allocator errors occur.

> External Sort BatchGroup leaks memory if an OOM occurs during read
> ------------------------------------------------------------------
>                 Key: DRILL-5210
>                 URL: https://issues.apache.org/jira/browse/DRILL-5210
>             Project: Apache Drill
>          Issue Type: Sub-task
>    Affects Versions: 1.9.0
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
> The External Sort operator (batch) can spill to disk when it runs out of memory. To do
so, it uses a class called {{BatchGroup}}. Later, when the sort merges spilled runs, {{BatchGroup}}
reads the run back into memory one batch at a time.
> If an OOM error occurs during the read operation, the partially-read batches leak: they
are not released. The fragment executor then issues a memory leak error while shutting down
the query.
> This error has probably not been caught until now because the {{BatchGroup}} code does
not make use of the fault injector. Elsewhere in the external sort, we use the fault injector
to insert a (simulated) OOM exception so we can determine if clean-up occurs properly. No
such fault injection code exists in {{BatchGroup}}.

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