[jira] [Commented] (HDFS-3990) NN's health report has severe performance problems

["liang xie (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-3990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13556060#comment-13556060 ] 

liang xie commented on HDFS-3990:
---------------------------------

we hit the same issue like [~cnauroth] on linux + CDH4.1.1 modified version,  only different is "0.0.0.0" , not "127.0.0.1".
so i changed the registerDatanode code snippet based the final patch:
{code}
      if (hostname.equals(ip)) {
        try {
          hostname = InetAddress.getByName(Server.getRemoteAddress()).
              getHostName();
        } catch (UnknownHostException e) {
          LOG.warn("Unable to lookup hostname for DataNode " +
              ip + " which registered with hostname " +
              nodeReg.getHostName());
          throw new DisallowedDatanodeException(nodeReg);
        }
      }
{code}

maybe it helpful for somebody else who hit the same issue.
                
> NN's health report has severe performance problems
> --------------------------------------------------
>
>                 Key: HDFS-3990
>                 URL: https://issues.apache.org/jira/browse/HDFS-3990
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 0.23.0, 2.0.0-alpha, 3.0.0
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>             Fix For: 3.0.0, 2.0.3-alpha, 0.23.5
>
>         Attachments: HDFS-3990.branch-0.23.patch, HDFS-3990.branch-0.23.patch, HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch, hdfs-3990.txt, hdfs-3990.txt
>
>
> The dfshealth page will place a read lock on the namespace while it does a dns lookup for every DN.  On a multi-thousand node cluster, this often results in 10s+ load time for the health page.  10 concurrent requests were found to cause 7m+ load times during which time write operations blocked.

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