[CASSANDRA-9206] Remove seed gossip probability

• Type: Improvement
• Status: Open
• Priority: Normal
• Resolution: Unresolved
• Fix Version/s: 5.x
• Component/s: Legacy/Distributed Metadata
• Assignee: Brandon Williams
• Reporter: Brandon Williams

Authors

Brandon Williams

• Created: 16/Apr/15 18:21
• Updated: 07/Mar/23 10:54

Description

Currently, we use probability to determine whether a node will gossip with a seed:

 
                double probability = seeds.size() / (double) (liveEndpoints.size() + unreachableEndpoints.size());
                double randDbl = random.nextDouble();
                if (randDbl <= probability)
                    sendGossip(prod, seeds);

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.

Issue Links

• depends upon: CASSANDRA-9401 Better check for gossip stabilization on startup