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Posted to common-dev@hadoop.apache.org by "Raghu Angadi (JIRA)" <ji...@apache.org> on 2009/05/22 20:28:45 UTC
[jira] Commented: (HADOOP-5890) Use exponential backoff on
Thread.sleep during DN shutdown
[ https://issues.apache.org/jira/browse/HADOOP-5890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12712195#action_12712195 ]
Raghu Angadi commented on HADOOP-5890:
--------------------------------------
Looking at trunk, there should not have been any wait since 'active threads is 0', right?
> Use exponential backoff on Thread.sleep during DN shutdown
> ----------------------------------------------------------
>
> Key: HADOOP-5890
> URL: https://issues.apache.org/jira/browse/HADOOP-5890
> Project: Hadoop Core
> Issue Type: Improvement
> Components: dfs
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: hadoop-5890.txt
>
>
> Tests waste a lot of time in DataNode.shutdown. Typical logs look like:
> {code}
> 2009-05-21 17:13:20,177 INFO datanode.DataNode (DataNode.java:shutdown(637)) - Waiting for threadgroup to exit, active threads is 0
> 2009-05-21 17:13:20,177 INFO datanode.DataBlockScanner (DataBlockScanner.java:run(620)) - Exiting DataBlockScanner thread.
> 2009-05-21 17:13:21,117 INFO datanode.DataNode (DataNode.java:shutdown(637)) - Waiting for threadgroup to exit, active threads is 0
> {code}
> In this example (and very commonly) the DataBlockScanner thread exits within 5-10ms after the first wait. The DN then sleeps an entire second before succeeding in shutting down.
> Using exponential backoff from a short value like 2ms up to a maximum of 1000ms would solve this.
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