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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7217) Better batching of IBRs
Date Wed, 08 Oct 2014 23:59:34 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7217?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14164417#comment-14164417
] 

Yongjun Zhang commented on HDFS-7217:
-------------------------------------

HI [~kihwal], 

I think the issue you described and patch you provided makes sense to me. You stated that
"60 to 70 percent of available handlers being constantly occupied by IBRs", I wonder if you
could share the new numbers after applying the patch, if you have? Thanks.

 

> Better batching of IBRs
> -----------------------
>
>                 Key: HDFS-7217
>                 URL: https://issues.apache.org/jira/browse/HDFS-7217
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Kihwal Lee
>         Attachments: HDFS-7217.patch
>
>
> After HDFS-2691 (pipeline recovery in HA), the number of IBR(incremental block report)s
have doubled.  Since processing of IBR requires exclusive FSNamesystem write lock, this can
be a source of significant overhead on clusters with high write load.  
> On one of the busy clusters, we have observed 60 to 70 percent of available handlers
being constantly occupied by IBRs. This degrades throughput greatly when compared to 0.23.



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