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Posted to common-dev@hadoop.apache.org by "Raghu Angadi (JIRA)" <ji...@apache.org> on 2008/09/08 18:25:44 UTC

[jira] Updated: (HADOOP-4116) DataNode : idle rebalancing operations need not take up threads.

     [ https://issues.apache.org/jira/browse/HADOOP-4116?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Raghu Angadi updated HADOOP-4116:
---------------------------------

    Description: 
The number of threads are currently limited on datanodes. Once these threads are occupied, DataNode does not accept any more requests (DOS). Recently we saw a case where most of the 256 threads were waiting in {{DataXceiver.replaceBlock()}} trying to acquire  {{balancingSem}}.  Since rebalancing  is (heavily) throttled, I would think this would be the common case. 

These operations waiting  for active rebalancing threads to finish need not take up a thread. 

  was:

The number of threads are currently limited on datanodes. Once these threads are occupied, DataNode does not accept any more requests (DOS). Recently we saw a case where most of the 256 threads were waiting in {{DataXceiver.replaceBlock()}} trying to acquire  {{balancingSem}}.  Since rebalancing  is (heavily) throttled, I would think this would be the common case. 

These waiting threads need not take up a thread. 

        Summary: DataNode : idle rebalancing operations need not take up threads.  (was: DataNode : idle rebalancing threads need not take up threads.)

> DataNode : idle rebalancing operations need not take up threads.
> ----------------------------------------------------------------
>
>                 Key: HADOOP-4116
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4116
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: dfs
>    Affects Versions: 0.17.0
>            Reporter: Raghu Angadi
>
> The number of threads are currently limited on datanodes. Once these threads are occupied, DataNode does not accept any more requests (DOS). Recently we saw a case where most of the 256 threads were waiting in {{DataXceiver.replaceBlock()}} trying to acquire  {{balancingSem}}.  Since rebalancing  is (heavily) throttled, I would think this would be the common case. 
> These operations waiting  for active rebalancing threads to finish need not take up a thread. 

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