[jira] [Created] (DRILL-5210) External Sort BatchGroup leaks memory if an OOM occurs during read

["Paul Rogers (JIRA)" <ji...@apache.org>]

Paul Rogers created DRILL-5210:
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             Summary: 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: Bug
    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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