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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 23:03:59 GMT

    [ https://issues.apache.org/jira/browse/HDFS-611?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12771181#action_12771181
] 

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

There are 3 approaches:
A1. Decrement the dfs usage when we schedule the task.
A2. Pass a handle of FSDataset to BlockFileDeleter ctor, so we can do "synchronized(fsdataset)
{ ... }" in the BlockFileDeleteTask
A3. Add a method in FSDataset for decrementing the dfs usage for a volume.

A1 is not good because the dfs usage won't be accurate.
A3 is changing the interface - but the method to decrement dfs usage shouldn't be exposed
from FSDataset I think.
I prefer A2.

Will that work?

> 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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