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Posted to issues@hive.apache.org by "Prasanth Jayachandran (JIRA)" <ji...@apache.org> on 2019/03/05 09:04:00 UTC

[jira] [Assigned] (HIVE-21391) LLAP: Pool of column vector buffers can cause memory pressure

     [ https://issues.apache.org/jira/browse/HIVE-21391?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Prasanth Jayachandran reassigned HIVE-21391:
--------------------------------------------

    Assignee: Prasanth Jayachandran

> LLAP: Pool of column vector buffers can cause memory pressure
> -------------------------------------------------------------
>
>                 Key: HIVE-21391
>                 URL: https://issues.apache.org/jira/browse/HIVE-21391
>             Project: Hive
>          Issue Type: Bug
>          Components: llap
>    Affects Versions: 4.0.0, 3.2.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Prasanth Jayachandran
>            Priority: Major
>
> Where there are too many columns (in the order of 100s), with decimal, string types the column vector pool of buffers created here [https://github.com/apache/hive/blob/master/llap-server/src/java/org/apache/hadoop/hive/llap/io/decode/EncodedDataConsumer.java#L59] can cause memory pressure. 
> Example:
> 128 (poolSize) * 300 (numCols) * 1024 (batchSize) * 80 (decimalSize) ~= 3GB
> The pool size keeps increasing when there is slow consumer but fast llap io (SSDs) leading to GC pressure when all LLAP io threads read splits from same table. 



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