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From "Sushanth Sowmyan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9359) Export of a large table causes OOM in Metastore and Client
Date Mon, 19 Jan 2015 22:27:34 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9359?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14283090#comment-14283090
] 

Sushanth Sowmyan commented on HIVE-9359:
----------------------------------------

I see your concern. Jackson has a streaming api style with JSONGenerator, but I haven't yet
been able to confirm if it generates the JSON object and then flushes as many others seem
to do, or whether it actually writes out as it receives instructions. I can investigate a
bit more on that end.

> Export of a large table causes OOM in Metastore and Client
> ----------------------------------------------------------
>
>                 Key: HIVE-9359
>                 URL: https://issues.apache.org/jira/browse/HIVE-9359
>             Project: Hive
>          Issue Type: Bug
>          Components: Import/Export, Metastore
>            Reporter: Sushanth Sowmyan
>            Assignee: Sushanth Sowmyan
>         Attachments: HIVE-9359.patch
>
>
> Running hive export on a table with a large number of partitions winds up making the
metastore and client run out of memory. The number of places we wind up having a copy of the
entire partitions object wind up being as follows:
> Metastore
>    * (temporarily) Metastore MPartition objects
>    * List<Partition> that gets persisted before sending to thrift
>    * thrift copy of all of those partitions
> Client side
>    * thrift copy of partitions
>    * deepcopy of above to create List<Partition> objects
>    * JSONObject that contains all of those above partition objects
>    * List<ReadEntity> which each encapsulates the aforesaid partition objects.
> This memory usage needs to be drastically reduced.



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