dcapwell commented on PR #4167: URL: https://github.com/apache/cassandra/pull/4167#issuecomment-2895212901
> shouldn't expect a very high amount of contention here, Writes are required to be in the `Stage.GOSSIP` other than the `EndpointState` for "this" instance, and that one uses the `taskLock` to block concurrent mutations... Personally feels like the CAS logic isn't required, but I really didn't want to change that type of behavior in this patch; there is always something unknown in gossip, so didn't want to poke a bear. > I suppose there is some risk of a livelock but I assume you've run this through the gossip simulator that would have found any issues. The locking patch wasn't run through simulation as it doesn't really help. Simulation runs several gossip instances on the same thread, so a lock in one code path would also be locked when entering another; so its not a good test to test locking issues. I did confirm in simulation that blocking access to the hb/state while its being mutated is enough to fix the issue. But given the way the simulation was done this was implemented by doing the following * when update hb, add a 30% chance to tell the simulation to "fake" blocking, and run other background work This was enough to hit this issue in the tests, and both locks and immutable view solve this by not making it possible to read incorrectly. The issue with the lock version is its not clear it covers everything and some times methods work with "clones" rather than the "global" version, so locks can be dumb some times... -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: pr-unsubscr...@cassandra.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: pr-unsubscr...@cassandra.apache.org For additional commands, e-mail: pr-h...@cassandra.apache.org
