On 15/02/2019 16:08, Christine Caulfield wrote: > On 15/02/2019 13:06, Edwin Török wrote: >> I tried again with 'debug: trace', lots of process pause here: >> https://clbin.com/ZUHpd >> >> And here is an strace running realtime prio 99, a LOT of epoll_wait and >> sendmsg (gz format): >> https://clbin.com/JINiV >> >> It detects large numbers of members left, but I think this is because >> the corosync on those hosts got similarly stuck: >> Feb 15 12:51:07 localhost corosync[29278]: [TOTEM ] A new membership >> (10.62.161.158:3152) was formed. Members left: 2 14 3 9 5 11 4 12 8 13 7 >> 1 10 >> Feb 15 12:51:07 localhost corosync[29278]: [TOTEM ] Failed to receive >> the leave message. failed: 2 14 3 9 5 11 4 12 8 13 7 1 10 >> >> Looking on another host that is still stuck 100% corosync it says: >> https://clbin.com/6UOn6 >> > > Thanks, that's really quite odd. I have vague recollections of a problem > where corosync was spinning on epoll without reading anything but can't > find the details at the moment, annoying. > > Some thing you might be able to try that might help. > > 1) is is possible to run without sbd. Sometimes too much polling from > clients can cause odd behaviour > 2) is it possible to try with a different kernel? We've tried a vanilla > 4.19 and it's fine, but not with the Xen patches obviously
I'll try with some bare-metal upstream distros and report back the repro steps if I can get it to reliably repro, hopefully early next week, it is unlikely I'll get a working repro today. > 3) Does running corosync with the -p option help? Yes, with "-p" I was able to run cluster create/GFS2 plug/unplug/destroy on 16 physical hosts in a loop for an hour with any crashes (previously it would crash within minutes). I found another workaround too: echo NO_RT_RUNTIME_SHARE >/sys/kernel/debug/sched_features This makes the 95% realtime process CPU limit from sched_rt_runtime_us/sched_rt_period_us apply per core, instead of globally, so there would be 5% time left for non-realtime tasks on each core. Seems to be enough to avoid the livelock, I was not able to observe corosync using high CPU % anymore. Still got more tests to run on this over the weekend, but looks promising. This is a safety layer of course, to prevent the system from fencing if we encounter high CPU usage in corosync/libq. I am still interested in tracking down the corosync/libq issue as it shouldn't have happened in the first place. > > Is there any situation where this has worked? either with different > components or different corosync.conf files? > > Also, and I don't think this is directly related to the issue, but I can > see configuration reloads happening from 2 nodes every 5 seconds. It's > very odd and maybe not what you want! The configuration reloads are a way of triggering this bug reliably, I should've mentioned that earlier (the problem happens during a configuration reload, but not always, and by doing configuration reloads in a loop that just add/remove one node the problem can be triggered reliably within minutes). Best regards, --Edwin _______________________________________________ Users mailing list: [email protected] https://lists.clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
