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https://issues.apache.org/jira/browse/HBASE-9393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13755464#comment-13755464
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Avi Zrachya commented on HBASE-9393:
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In our case it's definitely not because of many random reads.
On a cluster that have no traffic:
1. restart the regionserver on one node, the CLOSE_WAIT goes away..
2. wait few min and see that there are still 0 CLOSE_WAIT sockets.
2. re-balance the cluster so the new regionserver will get some regions.
3. As soon as the regionserver get some regions, many CLOSE_WAIT starts to show
up.
My assumption it happens when the regionserver reads/initialize the assigned
region.
Read data from the cluster dose not seems to affect the CLOSE_WAIT sockets..
but when regions in transition kicks in for whatever reason, the CLOSE_WAIT
stating to pump up.
> Hbase dose 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
> Environment: Centos 6.4 - 7 regionservers/datanodes, 8 TB per node,
> 7279 regions
> Reporter: Avi Zrachya
>
> 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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