Rushabh S Shah commented on HDFS-12278:

{{TestDFSStripedOutputStreamWithFailure150}} and 
{{TestDFSStripedOutputStreamWithFailure080}} are well known flaky tests.
Both have failed number of times. I ran 4 times each test. Fails with a 
probability of 50%
{{TestUnderReplicatedBlocks#testSetRepIncWithUnderReplicatedBlocks}} is timing 
out. Tracked via HDFS-9243.

There are no new tests since all the existing test covers the correctness.
Will attach a branch-2.8 patch soon.

> 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
>         Attachments: 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.

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