Rushabh S Shah created HDFS-12278:
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Summary: LeaseManager#removeLease operation is 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
After HDFS-6757, 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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