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Posted to hdfs-issues@hadoop.apache.org by "tomscut (Jira)" <ji...@apache.org> on 2021/09/06 09:26:00 UTC

[jira] [Updated] (HDFS-16209) Add description for dfs.namenode.caching.enabled

     [ https://issues.apache.org/jira/browse/HDFS-16209?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

tomscut updated HDFS-16209:
---------------------------
    Summary: Add description for dfs.namenode.caching.enabled  (was: Set dfs.namenode.caching.enabled to false as default)

> Add description for dfs.namenode.caching.enabled
> ------------------------------------------------
>
>                 Key: HDFS-16209
>                 URL: https://issues.apache.org/jira/browse/HDFS-16209
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>    Affects Versions: 3.1.0
>            Reporter: tomscut
>            Assignee: tomscut
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 1h 50m
>  Remaining Estimate: 0h
>
> Namenode config:
>  dfs.namenode.write-lock-reporting-threshold-ms=50ms
>  dfs.namenode.caching.enabled=true (default)
>  
> In fact, the caching feature is not used in our cluster, but this switch is turned on by default(dfs.namenode.caching.enabled=true), incurring some additional write lock overhead. We count the number of write lock warnings in a log file, and find that the number of rescan cache warnings reaches about 32%, which greatly affects the performance of Namenode.
> !namenode-write-lock.jpg!
>  
> We should set 'dfs.namenode.caching.enabled' to false by default and turn it on when we wants to use it.



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