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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. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira