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Posted to commits@cassandra.apache.org by "Brandon Williams (JIRA)" <ji...@apache.org> on 2015/05/15 21:44:01 UTC
[jira] [Updated] (CASSANDRA-9206) Remove seed gossip probability
[ https://issues.apache.org/jira/browse/CASSANDRA-9206?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Brandon Williams updated CASSANDRA-9206:
----------------------------------------
Fix Version/s: (was: 2.1.x)
3.x
> Remove seed gossip probability
> ------------------------------
>
> Key: CASSANDRA-9206
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9206
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Brandon Williams
> Assignee: Brandon Williams
> Fix For: 3.x
>
> Attachments: 9206.txt
>
>
> Currently, we use probability to determine whether a node will gossip with a seed:
> {noformat}
> double probability = seeds.size() / (double) (liveEndpoints.size() + unreachableEndpoints.size());
> double randDbl = random.nextDouble();
> if (randDbl <= probability)
> sendGossip(prod, seeds);
> {noformat}
> I propose that we remove this probability, and instead *always* gossip with a seed. This of course means increased traffic and processing on the seed(s), but even a 1000 node cluster with a single seed will only put ~1000 messages per second on the seed, which is virtually nothing. Should it become a problem, the solution is simple: add more seeds. Since seeds will also always gossip with each other, this effectively gives us a poor man's spanning tree, with the only cost being removing a few lines of code, and should greatly improve our gossip convergence time, especially in large clusters.
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