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From "huaxiang sun (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-17215) Separate small/large file delete threads in HFileCleaner to accelerate archived hfile cleanup speed
Date Thu, 30 Mar 2017 17:08:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-17215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15949419#comment-15949419
] 

huaxiang sun commented on HBASE-17215:
--------------------------------------

Thanks [~carp84], it is definitely fine to go with a follow-up to address the shared queue.

{quote}
I'm very much interested in this "some reason" (smile). Ever dig into it and mind share if
so? Thanks. huaxiang sun
{quote}

We have some rough idea about it. First, hdfs operation is slow, it takes 120 ms ~ 140 ms
to delete a file from hdfs. I think this Jira will help to address this issue (speed up +
delete large files to free up the diskspace). Another issue is related with SnapshotHFileCleaner,
refresh snapshot file cache is called very frequently, still looking into code to see if something
can be done there.



> Separate small/large file delete threads in HFileCleaner to accelerate archived hfile
cleanup speed
> ---------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-17215
>                 URL: https://issues.apache.org/jira/browse/HBASE-17215
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Yu Li
>            Assignee: Yu Li
>         Attachments: HBASE-17215.patch, HBASE-17215.v2.patch
>
>
> When using PCIe-SSD the flush speed will be really quick, and although we have per CF
flush, we still have the {{hbase.regionserver.optionalcacheflushinterval}} setting and some
other mechanism to avoid data kept in memory for too long to flush small hfiles. In our online
environment we found the single thread cleaner kept cleaning earlier flushed small files while
large files got no chance, which caused disk full then many other problems.
> Deleting hfiles in parallel with too many threads will also increase the workload of
namenode, so here we propose to separate large/small hfile cleaner threads just like we do
for compaction, and it turned out to work well in our cluster.



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