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Mingliang Liu commented on HDFS-9434: ------------------------------------- Thanks for working on this . The patch looks good to me. +1 (non-binding) pending on Jenkins. > Recommission a datanode with 500k blocks may pause NN for 30 seconds > -------------------------------------------------------------------- > > Key: HDFS-9434 > URL: https://issues.apache.org/jira/browse/HDFS-9434 > Project: Hadoop HDFS > Issue Type: Improvement > Components: namenode > Reporter: Tsz Wo Nicholas Sze > Assignee: Tsz Wo Nicholas Sze > Attachments: h9434_20151116.patch > > > In BlockManager, processOverReplicatedBlocksOnReCommission is called within > the namespace lock. There is a (not very useful) log message printed in > processOverReplicatedBlock. When there is a large number of blocks stored in > a storage, printing the log message for each block can pause NN to process > any other operations. We did see that it could pause NN for 30 seconds for > a storage with 500k blocks. > I suggest to change the log message to trace level as a quick fix. -- This message was sent by Atlassian JIRA (v6.3.4#6332)