[
https://issues.apache.org/jira/browse/HDFS-16209?focusedWorklogId=646215&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-646215
]
ASF GitHub Bot logged work on HDFS-16209:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 03/Sep/21 08:12
Start Date: 03/Sep/21 08:12
Worklog Time Spent: 10m
Work Description: tomscut commented on pull request #3378:
URL: https://github.com/apache/hadoop/pull/3378#issuecomment-912349488
> [HDFS-13820](https://issues.apache.org/jira/browse/HDFS-13820), added this
configuration to disable the feature, But still it was made to true by default,
guess due to compatibility reasons.
> Folks using the Cache feature would get impacted with this change, right?
they have to now enable this explicitly. There was a proposal on on
[HDFS-13820](https://issues.apache.org/jira/browse/HDFS-13820)
>
> ```
> Please implement a way to disable the CacheReplicationMonitor class if
there are no paths specified. Adding the first cached path to the NameNode
should kick off the CacheReplicationMonitor and when the last one is deleted,
the CacheReplicationMonitor should be disabled again.
> ```
>
> Is something like this possible?
Thanks @ayushtkn for your comments.
I have also seen
[HDFS-13820](https://issues.apache.org/jira/browse/HDFS-13820). But that
feature(auto enable or auto disable) is not currently implemented. For new
users who may not know this feature(Centralized Cache Management) exists, but
it already runs quietly in the background, which incurs performance overhead.
IMO, if we need to use this feature, it makes sense to turn it on and
specify the path. What do you think?
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
Issue Time Tracking
-------------------
Worklog Id: (was: 646215)
Time Spent: 50m (was: 40m)
> Set dfs.namenode.caching.enabled to false as default
> ----------------------------------------------------
>
> 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: 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.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org
