Hi Chris, Would you mind testing the following patch on your test clusters? I'm not entirely sure, but the issue might be related.
https://issues.apache.org/jira/browse/ZOOKEEPER-2930 Regards, Andor On Wed, Aug 8, 2018 at 6:51 PM, Camille Fournier <cami...@apache.org> wrote: > If you have the time and inclination, next time you see this problem in > your test clusters get stack traces and any other diagnostics possible > before restarting. I'm not an expert at network debugging but if you have > someone who is you might want them to take a look at the connections and > settings of any switches/firewalls/etc involved, see if there's any unusual > configurations or evidence of other long-lived connections failing (even if > their services handle the failures more gracefully). Send us the stack > traces also it would be interesting to take a look. > > C > > > On Wed, Aug 8, 2018, 11:09 AM Chris <c.turks...@gmail.com> wrote: > > > Running 3.5.5 > > > > I managed to recreate it on acc and test cluster today, failing on > > shutdown > > of leader. Both had been running for over a week. After restarting all > > zookeepers it runs fine no matter how many leader shutdowns i throw at > it. > > > > On 8 August 2018 5:05:34 pm Andor Molnar <an...@cloudera.com.INVALID> > > wrote: > > > > > Some kind of a network split? > > > > > > It looks like 1-2 and 3-4 were able to communicate each other, but > > > connection timed out between these 2 splits. When 5 came back online it > > > started with supporters of (1,2) and later 3 and 4 also joined. > > > > > > There was no such issue the day after. > > > > > > Which version of ZooKeeper is this? 3.5.something? > > > > > > Regards, > > > Andor > > > > > > > > > > > > On Wed, Aug 8, 2018 at 4:52 PM, Chris <c.turks...@gmail.com> wrote: > > > > > >> Actually i have similar issues on my test and acceptance clusters > where > > >> leader election fails if the cluster has been running for a couple of > > days. > > >> If you stop/start the Zookeepers once they will work fine on further > > >> disruptions that day. Not sure yet what the treshold is. > > >> > > >> > > >> On 8 August 2018 4:32:56 pm Camille Fournier <cami...@apache.org> > > wrote: > > >> > > >> Hard to say. It looks like about 15 minutes after your first incident > > where > > >>> 5 goes down and then comes back up, servers 1 and 2 get socket errors > > to > > >>> their connections with 3, 4, and 6. It's possible if you had waited > > those > > >>> 15 minutes, once those errors cleared the quorum would've formed with > > the > > >>> other servers. But as for why there were those errors in the first > > place > > >>> it's not clear. Could be a network glitch, or an obscure bug in the > > >>> connection logic. Has anyone else ever seen this? > > >>> If you see it again, getting a stack trace of the servers when they > > can't > > >>> form quorum might be helpful. > > >>> > > >>> On Wed, Aug 8, 2018 at 11:52 AM Cee Tee <c.turks...@gmail.com> > wrote: > > >>> > > >>> I have a cluster of 5 participants (id 1-5) and 1 observer (id 6). > > >>>> 1,2,5 are in datacenter A. 3,4,6 are in datacenter B. > > >>>> Yesterday one of the participants (id5, by chance was the leader) > was > > >>>> rebooted. Although all other servers were online and not suffering > > from > > >>>> networking issues the leader election failed and the cluster > remained > > >>>> "looking" until the old leader came back online after which it was > > >>>> promptly > > >>>> elected as leader again. > > >>>> > > >>>> Today we tried the same exercise on the exact same servers, 5 was > > still > > >>>> leader and was rebooted, and leader election worked fine with 4 as > new > > >>>> leader. > > >>>> > > >>>> I have included the logs. From the logs i see that yesterday 1,2 > > never > > >>>> received new leader proposals from 3,4 and vice versa. > > >>>> Today all proposals came through. This is not the first time we've > > seen > > >>>> this type of behavior, where some zookeepers can't seem to find each > > >>>> other > > >>>> after the leader goes down. > > >>>> All servers use dynamic configuration and have the same config node. > > >>>> > > >>>> How could this be explained? These servers also host a replicated > > >>>> database > > >>>> cluster and have no history of db replication issues. > > >>>> > > >>>> Thanks, > > >>>> Chris > > >>>> > > >>>> > > >>>> > > >>>> > > >> > > >> > > >> > > > > > > > > >
