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From "Allan Yang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-17757) Unify blocksize after encoding to decrease memory fragment
Date Tue, 14 Mar 2017 01:33:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-17757?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15923381#comment-15923381
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Allan Yang commented on HBASE-17757:
------------------------------------

{quote}
blockWriter.encodedBlockSizeWritten() >= encodedBlockSizeLimit || blockWriter.blockSizeWritten()
>= hFileContext.getBlocksize() so only the old way of block size determines the block boundary.

{quote}
So, if users set the blocksize to 64KB, and the default ratio is 1, then they will have blocks
whose size is 64KB AFTER encoding. But before this patch, if users set the blocksize to 64KB,
they will get blocks with 64KB BEFORE encoding. That is a difference.

> Unify blocksize after encoding to decrease memory fragment 
> -----------------------------------------------------------
>
>                 Key: HBASE-17757
>                 URL: https://issues.apache.org/jira/browse/HBASE-17757
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Allan Yang
>            Assignee: Allan Yang
>         Attachments: HBASE-17757.patch
>
>
> Usually, we store encoded block(uncompressed) in blockcache/bucketCache. Though we have
set the blocksize, after encoding, blocksize is varied. Varied blocksize will cause memory
fragment problem, which will result in more FGC finally.In order to relief the memory fragment,
This issue adjusts the encoded block to a unified size.



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