You are viewing a plain text version of this content. The canonical link for it is here.
Posted to hdfs-issues@hadoop.apache.org by "Ayush Saxena (JIRA)" <ji...@apache.org> on 2019/07/27 10:16:00 UTC
[jira] [Comment Edited] (HDFS-14370) Edit log tailing fast-path
should allow for backoff
[ https://issues.apache.org/jira/browse/HDFS-14370?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16894392#comment-16894392 ]
Ayush Saxena edited comment on HDFS-14370 at 7/27/19 10:15 AM:
---------------------------------------------------------------
Thanx [~xkrogen] for the patch, Seems fair enough,
A doubt, Is there any way to turn off this back-off mechanism? as if my requirement doesn't want me to have a backoff, usually we configure 0 interval for tailing edits for very loaded clusters, it may reach to a backoff stage may be easily, if for fractions the load is nil.
And secondly if I don't configure the back-off time, The default it shall take as 1 Min, so if my in general time is 0, the next shall get triggered at 1 Min, I guess by default we should keep the back-off disabled and the value of max-backoff to be same as that of sleeptimeMs if the max-backoff time isn't specified.
was (Author: ayushtkn):
Thanx [~xkrogen] for the patch, Seems fair enough,
A doubt, Is there any way to turn off this back-off mechanism? as if my requirement doesn't want me to have a backoff, usually we configure 0 interval for tailing edits for very loaded clusters, it may reach to a backoff stage may be easily, if for fractions the load is nil.
And secondly if I don't configure the back-off time, The default it shall take and 1 Min, so if my in general time is 0, the next shall get triggered at 1 Min, I guess by default we shouldn't keep the back-off disabled and the value of max-backoff to be same as that of sleeptimeMs if the max-backoff time isn't specified.
> Edit log tailing fast-path should allow for backoff
> ---------------------------------------------------
>
> Key: HDFS-14370
> URL: https://issues.apache.org/jira/browse/HDFS-14370
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode, qjm
> Affects Versions: 3.3.0
> Reporter: Erik Krogen
> Assignee: Erik Krogen
> Priority: Major
> Attachments: HDFS-14370.000.patch
>
>
> As part of HDFS-13150, in-progress edit log tailing was changed to use an RPC-based mechanism, thus allowing the edit log tailing frequency to be turned way down, and allowing standby/observer NameNodes to be only a few milliseconds stale as compared to the Active NameNode.
> When there is a high volume of transactions on the system, each RPC fetches transactions and takes some time to process them, self-rate-limiting how frequently an RPC is submitted. In a lightly loaded cluster, however, most of these RPCs return an empty set of transactions, consuming a high (de)serialization overhead for very little benefit. This was reported by [~jojochuang] in HDFS-14276 and I have also seen it on a test cluster where the SbNN was submitting 8000 RPCs per second that returned empty.
> I propose we add some sort of backoff to the tailing, so that if an empty response is received, it will wait a longer period of time before submitting a new RPC.
--
This message was sent by Atlassian JIRA
(v7.6.14#76016)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-help@hadoop.apache.org