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https://issues.apache.org/jira/browse/HBASE-9393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15213842#comment-15213842
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Ashish Singhi commented on HBASE-9393:
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I replied to them in my above comment. It is not mandatory to call them in a
lock so only I did not add any specific javadoc for it.
{quote}
bq. This call means that openReader can only be called within a lock for fsdis.
The javadocs should say so. (do all uses already do this?)
bq. This call means that createReader(FileSystem, Path,
FSDataInputStreamWrapper, long, CacheConfig, Configuration) can only be called
within a lock for fsdis, javadocs should say so. (do all uses already do this?)
As per my knowledge the concurrent thing is already handled in HDFS. Each
client will have its own BlockReader and socket, so if the first client
unbuffer the socket also it will not cause any problem to the other client
block reads.
{quote}
> Hbase does not closing a closed socket resulting in many CLOSE_WAIT
> --------------------------------------------------------------------
>
> Key: HBASE-9393
> URL: https://issues.apache.org/jira/browse/HBASE-9393
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.94.2, 0.98.0
> Environment: Centos 6.4 - 7 regionservers/datanodes, 8 TB per node,
> 7279 regions
> Reporter: Avi Zrachya
> Assignee: Ashish Singhi
> Priority: Critical
> Fix For: 2.0.0
>
> Attachments: HBASE-9393.patch, HBASE-9393.v1.patch,
> HBASE-9393.v10.patch, HBASE-9393.v11.patch, HBASE-9393.v12.patch,
> HBASE-9393.v13.patch, HBASE-9393.v14.patch, HBASE-9393.v15.patch,
> HBASE-9393.v15.patch, HBASE-9393.v2.patch, HBASE-9393.v3.patch,
> HBASE-9393.v4.patch, HBASE-9393.v5.patch, HBASE-9393.v5.patch,
> HBASE-9393.v5.patch, HBASE-9393.v6.patch, HBASE-9393.v6.patch,
> HBASE-9393.v6.patch, HBASE-9393.v7.patch, HBASE-9393.v8.patch,
> HBASE-9393.v9.patch
>
>
> HBase dose not close a dead connection with the datanode.
> This resulting in over 60K CLOSE_WAIT and at some point HBase can not connect
> to the datanode because too many mapped sockets from one host to another on
> the same port.
> The example below is with low CLOSE_WAIT count because we had to restart
> hbase to solve the porblem, later in time it will incease to 60-100K sockets
> on CLOSE_WAIT
> [root@hd2-region3 ~]# netstat -nap |grep CLOSE_WAIT |grep 21592 |wc -l
> 13156
> [root@hd2-region3 ~]# ps -ef |grep 21592
> root 17255 17219 0 12:26 pts/0 00:00:00 grep 21592
> hbase 21592 1 17 Aug29 ? 03:29:06
> /usr/java/jdk1.6.0_26/bin/java -XX:OnOutOfMemoryError=kill -9 %p -Xmx8000m
> -ea -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode
> -Dhbase.log.dir=/var/log/hbase
> -Dhbase.log.file=hbase-hbase-regionserver-hd2-region3.swnet.corp.log ...
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