[
https://issues.apache.org/jira/browse/HDFS-12278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16120726#comment-16120726
]
Rushabh S Shah commented on HDFS-12278:
---------------------------------------
Thanks [~kihwal] for the review and commit !
Thanks [~daryn] for the benchmarking the change.
> LeaseManager operations are inefficient in 2.8.
> -----------------------------------------------
>
> Key: HDFS-12278
> URL: https://issues.apache.org/jira/browse/HDFS-12278
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.8.0
> Reporter: Rushabh S Shah
> Assignee: Rushabh S Shah
> Priority: Blocker
> Fix For: 2.9.0, 3.0.0-beta1, 2.8.2
>
> Attachments: HDFS-12278-branch-2.8.001.patch, HDFS-12278.patch
>
>
> After HDFS-6757, LeaseManager #removeLease became expensive.
> HDFS-6757 changed the {{sortedLeases}} object from TreeSet to PriorityQueue.
> Previously the {{remove(Object)}} operation from {{sortedLeases}} was {{O(log
> n)}} but after the change it became {{O( n)}} since it has to find the object
> first.
> Recently we had an incident in one of our production cluster just hours after
> we upgraded from 2.7 to 2.8
> The {{sortledLeases}} object had approximately 100,000 items within it.
> While removing the lease, it will acquire the LeaseManager lock and that will
> slow down the lookup of lease also.
> HDFS-6757 is a good improvement which replaced the path by inode id.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org
