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Zhihong Yu commented on HBASE-5913: ----------------------------------- I looped TestClassLoading 5 times using patch v2 and they passed. > Speed up the full scan of META > ------------------------------ > > Key: HBASE-5913 > URL: https://issues.apache.org/jira/browse/HBASE-5913 > Project: HBase > Issue Type: Improvement > Reporter: chunhui shen > Assignee: chunhui shen > Attachments: 5913-v2.txt, HBASE-5913.patch > > > In the master, we will do the full scan of META in some situations > for example, > 1.master start up > 2.CatalogJanitor do the full scan per 5 mins > 3.ServerShutdownHandler, getServerUserRegions for dead server. > For the online applications, we should try the best to reduce the process > time of ServerShutdownHandler in the situation 3. > However, we found MetaReader#getServerUserRegions take 14mins for 10w regions > in our production environment. > And it is caused by two reasons: > The first, we don't use cache and get one row per next() when fully scan > .META. > The second, "hbase.ipc.client.tcpnodelay" is false as default, and in our > environment it take 40ms for per next() (It is related to the length of row > in the .META. , if someone also found, could try to set it true) > For this issue, I think we could set the caching when do the full scan of META -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira