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https://issues.apache.org/jira/browse/HADOOP-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13233788#comment-13233788
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Hudson commented on HADOOP-8191:
--------------------------------
Integrated in Hadoop-Common-trunk-Commit #1907 (See
[https://builds.apache.org/job/Hadoop-Common-trunk-Commit/1907/])
HADOOP-8191. SshFenceByTcpPort uses netcat incorrectly. Contributed by Todd
Lipcon. (Revision 1303148)
Result = SUCCESS
todd : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1303148
Files :
* /hadoop/common/trunk/hadoop-common-project/hadoop-common/CHANGES.txt
*
/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ha/SshFenceByTcpPort.java
*
/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ha/TestSshFenceByTcpPort.java
> SshFenceByTcpPort uses netcat incorrectly
> -----------------------------------------
>
> Key: HADOOP-8191
> URL: https://issues.apache.org/jira/browse/HADOOP-8191
> Project: Hadoop Common
> Issue Type: Bug
> Components: ha
> Affects Versions: 0.23.3
> Reporter: Philip Zeyliger
> Assignee: Todd Lipcon
> Fix For: 0.24.0, 0.23.3
>
> Attachments: hdfs-3081.txt
>
>
> SshFencyByTcpPort currently assumes that the NN is listening on localhost.
> Typical setups have the namenode listening just on the hostname of the
> namenode, which would lead "nc -z" to not catch it.
> Here's an example in which the NN is running, listening on 8020, but doesn't
> respond to "localhost 8020".
> {noformat}
> [root@xxx ~]# lsof -P -p 5286 | grep -i listen
> java 5286 root 110u IPv4 1772357 TCP xxx:8020
> (LISTEN)
> java 5286 root 121u IPv4 1772397 TCP xxx:50070
> (LISTEN)
> [root@xxx ~]# nc -z localhost 8020
> [root@xxx ~]# nc -z xxx 8020
> Connection to xxx 8020 port [tcp/intu-ec-svcdisc] succeeded!
> {noformat}
> Here's the likely offending code:
> {code}
> LOG.info(
> "Indeterminate response from trying to kill service. " +
> "Verifying whether it is running using nc...");
> rc = execCommand(session, "nc -z localhost 8020");
> {code}
> Naively, we could rely on netcat to the correct hostname (since the NN ought
> to be listening on the hostname it's configured as), or just to use fuser.
> Fuser catches ports independently of what IPs they're bound to:
> {noformat}
> [root@xxx ~]# fuser 1234/tcp
> 1234/tcp: 6766 6768
> [root@xxx ~]# jobs
> [1]- Running nc -l localhost 1234 &
> [2]+ Running nc -l rhel56-18.ent.cloudera.com 1234 &
> [root@xxx ~]# sudo lsof -P | grep -i LISTEN | grep -i 1234
> nc 6766 root 3u IPv4 2563626
> TCP localhost:1234 (LISTEN)
> nc 6768 root 3u IPv4 2563671
> TCP xxx:1234 (LISTEN)
> {noformat}
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