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From "stone (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-11569) Track message latency across DCs
Date Wed, 18 May 2016 06:27:13 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-11569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15288506#comment-15288506
] 

stone commented on CASSANDRA-11569:
-----------------------------------

use ipfw tool to set datacenter latency.

I also use trace to confirm the latency is valuable.

QueryTrace queryTrace = executionInfo.getQueryTrace();
when there is 10ms latency,no problem.and when there is 100ms latency,I will got an error
as the crosslatency is too large.

so I doubt the value of CrossNodeLatency

> Track message latency across DCs
> --------------------------------
>
>                 Key: CASSANDRA-11569
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11569
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Observability
>            Reporter: Chris Lohfink
>            Assignee: Chris Lohfink
>            Priority: Minor
>         Attachments: CASSANDRA-11569.patch
>
>
> Since we have the timestamp a message is created and when arrives, we can get an approximate
time it took relatively easy and would remove necessity for more complex hacks to determine
latency between DCs.
> Although is not going to be very meaningful when ntp is not setup, it is pretty common
to have NTP setup and even with clock drift nothing is really hurt except the metric becoming
whacky.



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