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https://issues.apache.org/jira/browse/HIVE-11467?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14662417#comment-14662417
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Sergey Shelukhin commented on HIVE-11467:
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The latest patch again changes it from lower to higher power of two... should
it be lower?
Otherwise looks good
> WriteBuffers rounding wbSize to next power of 2 may cause OOM
> -------------------------------------------------------------
>
> Key: HIVE-11467
> URL: https://issues.apache.org/jira/browse/HIVE-11467
> Project: Hive
> Issue Type: Bug
> Components: Hive
> Affects Versions: 1.2.0, 2.0.0
> Reporter: Wei Zheng
> Assignee: Wei Zheng
> Attachments: HIVE-11467.01.patch, HIVE-11467.02.patch,
> HIVE-11467.03.patch
>
>
> If wbSize passed to WriteBuffers cstr is not power of 2, it will do a
> rounding first to the next power of 2
> {code}
> public WriteBuffers(int wbSize, long maxSize) {
> this.wbSize = Integer.bitCount(wbSize) == 1 ? wbSize :
> (Integer.highestOneBit(wbSize) << 1);
> this.wbSizeLog2 = 31 - Integer.numberOfLeadingZeros(this.wbSize);
> this.offsetMask = this.wbSize - 1;
> this.maxSize = maxSize;
> writePos.bufferIndex = -1;
> nextBufferToWrite();
> }
> {code}
> That may break existing memory consumption assumption for mapjoin, and
> potentially cause OOM.
> The solution will be to pass a power of 2 number as wbSize from upstream
> during hashtable creation, to avoid this late expansion.
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