[jira] [Commented] (HDFS-8966) Separate the lock used in namespace and block management layer

["He Xiaoqiao (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-8966?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16373861#comment-16373861 ] 

He Xiaoqiao commented on HDFS-8966:
-----------------------------------

[~wheat9],[~jingzhao] is this issue still ongoing?

> Separate the lock used in namespace and block management layer
> --------------------------------------------------------------
>
>                 Key: HDFS-8966
>                 URL: https://issues.apache.org/jira/browse/HDFS-8966
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Haohui Mai
>            Assignee: Haohui Mai
>            Priority: Major
>
> Currently the namespace and the block management layer share one giant lock. One consequence that we have seen more and more often is that the namespace hangs due to excessive activities from the block management layer. For example, the NN might take a couple hundred milliseconds to handle a large block report. Because the NN holds the write lock during processing the block report, all namespace requests are paused. In production we have seen these lock contentions cause long latencies and instabilities in the cluster.
> This umbrella jira proposes to separate the lock used by namespace and the block management layer.



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