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Kihwal Lee commented on HDFS-9198: ---------------------------------- We have applied this internally to 2.7 and run for quite some time. So I would say it is safe. HDFS-8999 and HDFS-9710 will make it less important, but since these are more invasive and risky, HDFS-9198 in 2.7 might be a better alternative for now. > Coalesce IBR processing in the NN > --------------------------------- > > Key: HDFS-9198 > URL: https://issues.apache.org/jira/browse/HDFS-9198 > Project: Hadoop HDFS > Issue Type: Improvement > Components: namenode > Affects Versions: 2.0.0-alpha > Reporter: Daryn Sharp > Assignee: Daryn Sharp > Fix For: 2.8.0 > > Attachments: HDFS-9198-Branch-2-withamend.diff, > HDFS-9198-Branch-2.8-withamend.diff, HDFS-9198-branch2.patch, > HDFS-9198-trunk.patch, HDFS-9198-trunk.patch, HDFS-9198-trunk.patch, > HDFS-9198-trunk.patch, HDFS-9198-trunk.patch > > > IBRs from thousands of DNs under load will degrade NN performance due to > excessive write-lock contention from multiple IPC handler threads. The IBR > processing is quick, so the lock contention may be reduced by coalescing > multiple IBRs into a single write-lock transaction. The handlers will also > be freed up faster for other operations. -- This message was sent by Atlassian JIRA (v6.3.4#6332)