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From "Kang Yuan (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (PHOENIX-4021) Remove CachingHTableFactory
Date Tue, 19 Sep 2017 14:51:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16171811#comment-16171811
] 

Kang Yuan edited comment on PHOENIX-4021 at 9/19/17 2:50 PM:
-------------------------------------------------------------

we backport this patch to phoenix4.11-HBase-0.98 .The performance go down a lot when CachineHTableFactory
is disabled, so many HTables were been created and used once.It's waste and lower the performance

can we make CachingHTableFactory thread safe instead of removing it


was (Author: kirayuan):
we backport this patch to phoenix4.11-HBase-0.98 .The performance go down a lot when CachineHTableFactory
is disabled, so many HTables were been created and used once.It's wast and lower the performance

can we make CachingHTableFactory thread safe instead of removing it

> Remove CachingHTableFactory
> ---------------------------
>
>                 Key: PHOENIX-4021
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4021
>             Project: Phoenix
>          Issue Type: Bug
>    Affects Versions: 4.11.0
>            Reporter: Geoffrey Jacoby
>            Assignee: Geoffrey Jacoby
>              Labels: globalMutableSecondaryIndex
>             Fix For: 4.12.0
>
>         Attachments: PHOENIX-4021.patch
>
>
> CachingHTableFactory is used as a performance optimization when writing to global indexes
so that HTable instances are cached and later automatically cleaned up, rather than instantiated
each time we write to an index.
> This should be removed for two reasons:
> 1. It opens us up to race conditions, because HTables aren't threadsafe, but CachingHTableFactory
doesn't guard against two threads both grabbing the same HTable and using it simultaneously.
Since all ops going through a region share the same IndexWriter and ParallelWriterIndexCommitter,
and hence the same CachingHTableFactory, that means separate operations can both be holding
the same HTable. 
> 2. According to discussion on PHOENIX-3159, and offline discussions I've had with [~apurtell],
HBase 1.x and above make creating throwaway HTable instances cheap so the caching is no longer
needed.
> For 4.x-HBase-1.x and master, we should remove CachingHTableFactory, and for 4.x-HBase-0.98,
we should either get rid of it (if it's not too much of a perf hit) or at least make it threadsafe.



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