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https://issues.apache.org/jira/browse/HIVE-21391?focusedWorklogId=261227&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-261227
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ASF GitHub Bot logged work on HIVE-21391:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 17/Jun/19 08:24
            Start Date: 17/Jun/19 08:24
    Worklog Time Spent: 10m 
      Work Description: prasanthj commented on issue #641: HIVE-21391: Fix  
VRBsQueue size estimate
URL: https://github.com/apache/hive/pull/641#issuecomment-502584489
 
 
   +1
 
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Issue Time Tracking
-------------------

    Worklog Id:     (was: 261227)
    Time Spent: 20m  (was: 10m)

> 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
>              Labels: pull-request-available
>         Attachments: HIVE-21391.1.patch
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> 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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