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https://issues.apache.org/jira/browse/HDFS-5757?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ming Ma updated HDFS-5757:
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Resolution: Duplicate
Status: Resolved (was: Patch Available)
This optimization has been taken care of by HDFS-7411.
> refreshNodes with many 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
> Assignee: Ming Ma
> Attachments: HDFS-5757.patch
>
>
> 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.
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