[
https://issues.apache.org/jira/browse/CASSANDRA-6683?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13899277#comment-13899277
]
Tyler Hobbs commented on CASSANDRA-6683:
----------------------------------------
[~brandon.williams] was our motivation for not calling
{{sortByProximityWithScore}} every time just the overhead of that operation? It
seems like it shouldn't have a large impact unless the RF is high. If we want
to handle the high-RF case more efficiently, perhaps we could add a parameter
that specifies how many of the replicas will be used (based on the consistency
level) and just move the N lowest scores to the front if the first N scores
aren't within BADNESS_THRESHOLD.
> BADNESS_THRESHOLD does not working correctly with DynamicEndpointSnitch
> -----------------------------------------------------------------------
>
> Key: CASSANDRA-6683
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6683
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Environment: Linux 3.8.0-33-generic
> Reporter: Kirill Bogdanov
> Labels: snitch
> Fix For: 2.0.6
>
>
> There is a problem in *DynamicEndpointSnitch.java* in
> sortByProximityWithBadness()
> Before calling sortByProximityWithScore we comparing each nodes score ratios
> to the badness threshold.
> {code}
> if ((first - next) / first > BADNESS_THRESHOLD)
> {
> sortByProximityWithScore(address, addresses);
> return;
> }
> {code}
> This is not always the correct comparison because *first* score can be less
> than *next* score and in that case we will compare a negative number with
> positive.
> The solution is to compute absolute value of the ratio:
> {code}
> if (Math.abs((first - next) / first) > BADNESS_THRESHOLD)
> {code}
> This issue causing an incorrect sorting of DCs based on their performance and
> affects performance of the snitch.
> Thanks.
>
--
This message was sent by Atlassian JIRA
(v6.1.5#6160)
