hadoop-hdfs-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4183) Throttle block recovery
Date Tue, 13 Nov 2012 21:00:13 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4183?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13496535#comment-13496535
] 

Todd Lipcon commented on HDFS-4183:
-----------------------------------

A few thoughts:
1) Could we simply jitter the lease expiration time? The 1 hour limit isn't anything precise
which a user would depend on. I could see adding a 10% jitter to smooth out the expirations
over time.
2) Any idea why it's so slow aside from the logging? Do we have a silly bug where we are logSyncing
while holding the lock or something?
                
> Throttle block recovery
> -----------------------
>
>                 Key: HDFS-4183
>                 URL: https://issues.apache.org/jira/browse/HDFS-4183
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: name-node
>    Affects Versions: 0.23.4, 2.0.2-alpha
>            Reporter: Kihwal Lee
>            Assignee: Kihwal Lee
>            Priority: Critical
>
> When a large number of files are abandoned without closing, a storm of lease expiration
follows in about an hour (lease hard limit). For the last block of each file, block recovery
is initiated and when the datanode is done, it calls commitBlockSynchronization() is called
against namenode. A burst of these calls can slow down namenode considerably. We need to throttle
block recovery and/or speed up the rate at which commitBlockSynchronization() is served.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message