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https://issues.apache.org/jira/browse/HDFS-15037?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16990275#comment-16990275
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Konstantin Shvachko commented on HDFS-15037:
--------------------------------------------
Ah, OK. Good catch Wei-Chiu. So may be {{dirLock}}-only locking in these
methods was introduced by mistake then, and we should fix it in a different
issue? [~xiaochen] may be you could give some background here.
In any case it would be good to make KMS calls outside of the namesystem lock.
> Encryption Zone operations should not block other RPC calls while retreiving
> encryption keys.
> ---------------------------------------------------------------------------------------------
>
> Key: HDFS-15037
> URL: https://issues.apache.org/jira/browse/HDFS-15037
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: encryption, namenode
> Affects Versions: 2.10.0
> Reporter: Konstantin Shvachko
> Priority: Major
>
> I believe it was an intention to avoid blocking other operations while
> retrieving keys with holding {{FSDirectory.dirLock}}. But in reality all
> other operations enter first {{FSNamesystemLock}} then {{dirLock}}. So they
> are all blocked waiting for the key.
> We see substantial increase in RPC wait time ({{RpcQueueTimeAvgTime}}) on
> NameNode when encryption operations are intermixed with regular workloads.
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