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https://issues.apache.org/jira/browse/HADOOP-16828?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17306995#comment-17306995
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Stephen O'Donnell commented on HADOOP-16828:
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[~fengnanli] These seems like a great change to backport onto the 3.3 branch.
Out of interest, what batch size do you configure on your cluster? Is this
change still running well with no issues on your cluster?
> Zookeeper Delegation Token Manager fetch sequence number by batch
> -----------------------------------------------------------------
>
> Key: HADOOP-16828
> URL: https://issues.apache.org/jira/browse/HADOOP-16828
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Fengnan Li
> Assignee: Fengnan Li
> Priority: Major
> Fix For: 3.4.0
>
> Attachments: HADOOP-16828.001.patch, HADOOP-16828.002.patch, Screen
> Shot 2020-01-25 at 2.25.06 PM.png, Screen Shot 2020-01-25 at 2.25.16 PM.png,
> Screen Shot 2020-01-25 at 2.25.24 PM.png
>
>
> Currently in ZKDelegationTokenSecretManager.java the seq number is
> incremented by 1 each time there is a request for creating new token. This
> will need to send traffic to Zookeeper server. With multiple managers
> running, there is data contention going on. Also, since the current logic of
> incrementing is using tryAndSet which is optimistic concurrency control
> without locking. This data contention is having performance degradation when
> the secret manager are under volume of traffic.
> The change here is to fetching this seq number by batch instead of 1, which
> will reduce the traffic sent to ZK and make many operations inside ZK secret
> manager's memory.
> After putting this into production we saw huge improvement to the RPC
> processing latency of get delegationtoken calls. Also, since ZK takes less
> traffic in this way. Other write calls, like renew and cancel delegation
> tokens are benefiting from this change.
>
>
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