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From "Zheng Shao (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-611) Heartbeats times from Datanodes increase when there are plenty of blocks to delete
Date Wed, 28 Oct 2009 23:19:59 GMT

    [ https://issues.apache.org/jira/browse/HDFS-611?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12771191#action_12771191
] 

Zheng Shao commented on HDFS-611:
---------------------------------

A4. Do "synchronized(fsdataset)" in "void decDfsUsed(...)". That function is called only from
"BlockFileDeleteTask" now.
A5. Do "synchronized void decDfsUsed(...)". This will move the lock down to the volume, to
make it faster.

Although A5 might help us avoid some contentions, I don't see any code that locks a volume.
I guess we always lock the FSDataset.

I prefer A4 the best.


> Heartbeats times from Datanodes increase when there are plenty of blocks to delete
> ----------------------------------------------------------------------------------
>
>                 Key: HDFS-611
>                 URL: https://issues.apache.org/jira/browse/HDFS-611
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: data-node
>    Affects Versions: 0.20.1, 0.21.0, 0.22.0
>            Reporter: dhruba borthakur
>            Assignee: Zheng Shao
>             Fix For: 0.20.2, 0.21.0, 0.22.0
>
>         Attachments: HDFS-611.branch-19.patch, HDFS-611.branch-20.patch, HDFS-611.trunk.patch
>
>
> I am seeing that when we delete a large directory that has plenty of blocks, the heartbeat
times from datanodes increase significantly from the normal value of 3 seconds to as large
as 50 seconds or so. The heartbeat thread in the Datanode deletes a bunch of blocks sequentially,
this causes the heartbeat times to increase.

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