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Posted to commits@cassandra.apache.org by "Jay Zhuang (JIRA)" <ji...@apache.org> on 2018/03/19 17:16:00 UTC
[jira] [Updated] (CASSANDRA-14252) Use zero as default score in
DynamicEndpointSnitch
[ https://issues.apache.org/jira/browse/CASSANDRA-14252?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jay Zhuang updated CASSANDRA-14252:
-----------------------------------
Attachment: IMG_3180.jpg
> Use zero as default score in DynamicEndpointSnitch
> --------------------------------------------------
>
> Key: CASSANDRA-14252
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14252
> Project: Cassandra
> Issue Type: Bug
> Components: Coordination
> Reporter: Dikang Gu
> Assignee: Dikang Gu
> Priority: Major
> Fix For: 4.0, 3.0.17, 3.11.3
>
> Attachments: IMG_3180.jpg
>
>
> The problem I want to solve is that I found in our deployment, one slow but alive data node can slow down the whole cluster, even caused timeout of our requests.
> We are using DynamicEndpointSnitch, with badness_threshold 0.1. I expect the DynamicEndpointSnitch switch to sortByProximityWithScore, if local data node latency is too high.
> I added some debug log, and figured out that in a lot of cases, the score from remote data node was not populated, so the fallback to sortByProximityWithScore never happened. That's why a single slow data node, can cause huge problems to the whole cluster.
> In this jira, I'd like to use zero as default score, so that we will get a chance to try remote data node, if local one is slow.
> I tested it in our test cluster, it improved the client latency in single slow data node case significantly.
> I flag this as a Bug, because it caused problems to our use cases multiple times.
> ==== logs ===
> _2018-02-21_23:08:57.54145 WARN 23:08:57 [RPC-Thread:978]: sortByProximityWithBadness: after sorting by proximity, addresses order change to [ip1, ip2], with scores [1.0]_
> _2018-02-21_23:08:57.54319 WARN 23:08:57 [RPC-Thread:967]: sortByProximityWithBadness: after sorting by proximity, addresses order change to [ip1, ip2], with scores [0.0]_
> _2018-02-21_23:08:57.55111 WARN 23:08:57 [RPC-Thread:453]: sortByProximityWithBadness: after sorting by proximity, addresses order change to [ip1, ip2], with scores [1.0]_
> _2018-02-21_23:08:57.55687 WARN 23:08:57 [RPC-Thread:753]: sortByProximityWithBadness: after sorting by proximity, addresses order change to [ip1, ip2], with scores [1.0]_
>
>
>
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