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Posted to issues@hive.apache.org by "Prasanth Jayachandran (JIRA)" <ji...@apache.org> on 2019/03/06 20:50:00 UTC
[jira] [Commented] (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:comment-tabpanel&focusedCommentId=16786124#comment-16786124 ]
Prasanth Jayachandran commented on HIVE-21391:
----------------------------------------------
[~gopalv] can you please review this patch? The strong ref fixed object pool of CVBs is made to weak ref.
> 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
> Attachments: HIVE-21391.1.patch
>
>
> 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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