Ming Ma created HDFS-5757: ----------------------------- Summary: Decommisson lots of nodes at the same time could slow down NN Key: HDFS-5757 URL: https://issues.apache.org/jira/browse/HDFS-5757 Project: Hadoop HDFS Issue Type: Improvement Components: namenode Reporter: Ming Ma
Sometimes we need to decomm a whole rack of nodes at the same time. When the decomm is in process; NN is slow. The reason is when DecommissionManager checks the decomm status, it acquires namesystem's writer lock and iterates through all DNs; for each DN that is in decommissioning state, it check if replication is done for all the blocks on the machine via blockManager.isReplicationInProgress; for large cluster; the number of blocks on the machine could be big. The fix could be to have DecommissionManager check for several decomm-in-progress nodes each time it aquires namesystem's writer lock. -- This message was sent by Atlassian JIRA (v6.1.5#6160)