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https://issues.apache.org/jira/browse/HDFS-1325?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12895431#action_12895431
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Suresh Srinivas commented on HDFS-1325:
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You said you are opening files to scan it. After scanning is done, you can
close input stream right? Can you please describe what is happening in the code
and why you cannot close the input stream?
> DFSClient(DFSInputStream) release the persistent connection with datanode
> when no data have been read for a long time
> ---------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-1325
> URL: https://issues.apache.org/jira/browse/HDFS-1325
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs client
> Reporter: jinglong.liujl
> Fix For: 0.20.3
>
> Attachments: dfsclient.patch, toomanyconnction.patch
>
>
> When you use Hbase over hadoop. We found during scanning over a large table (
> which has many regions and each region has many store files), there're too
> many connections has been kept between regionserver (act as DFSClient) and
> datanode. Even if the store file has been complete to scanning, the
> connections can not be closed.
> In our cluster, too many extra connections cause too many system resource has
> been wasted, which cause system cpu on region server reach to a high level,
> then bring this region server down.
> After investigating, we found the number of active connection is very small,
> and the most connection is idle. We add a timeout checker thread into
> DFSClient, to close this connection.
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