Il giorno ven 4 gen 2019 alle ore 14:23 Andor Molnar <an...@apache.org> ha scritto: > > Hi team / Enrico, > > I’d like to get feedback from the community on the following patch (moving > the discussion from GitHub to here): > > https://issues.apache.org/jira/browse/ZOOKEEPER-3204 > <https://issues.apache.org/jira/browse/ZOOKEEPER-3204> > https://github.com/apache/zookeeper/pull/753 > <https://github.com/apache/zookeeper/pull/753> > > In a nutshell: looks like that Netty 3.10 is broken under Java 11: it doesn’t > properly close the underlying socket (probably not closing the registered NIO > selectors) and reconfig tests are unable to re-bind the ports. This problem > is similar that we already fixed in NIO with the following patch: > https://github.com/apache/zookeeper/commit/c3babb94275ad667dc71c10dcb08a383a3c154c2 > > <https://github.com/apache/zookeeper/commit/c3babb94275ad667dc71c10dcb08a383a3c154c2> > The problem doesn’t show up on trunk which has been recently upgraded to > Netty 4. > > Repro: > - Start embedded ZK, stop it and try to restart on the same port, or > - Start normal ensemble and reconfig to use different (client) port. Then > reconfig back to the original port which should fail. (that’s the scenario > which is covered in ReconfigTest) > > I created the above patch (#753) to backport Netty 4 upgrade to 3.5 and it > fixes the problem with Java 11 (it doesn’t cause regression in the pre-commit > build either), but Enrico is having concerns about making such big change > before the release. > > I tend to agree, but let’s see what are the options. > > Thoughts: > - Do we have to fix this? - Yes. Java 11 is LTS and I the bug is critical. > - Can we fix Netty 3? - Maybe. Let’s say we find the bug in Netty 3, what can > we do? > a) We cannot workaround from ZooKeeper itself and have to submit a > pull request for Netty. I think it’s quite unlikely that they will accept the > change given it’s not a security bug, but even if they did, only the upgraded > version of Netty 3 would work properly with ZooKeeper. Err. > b) We can workaround it from ZooKeeper: that could be option #1, but I > have a strong feeling about it’s not going to be the case. > - Shall we upgrade to Netty 4? - this is option #2 > > Please share your thoughts, maybe you know about an option #3.
Thank you Andor I have thought more about this problem, and I have checked that Netty 3 is really dead/unmantained (last release in 2016). If I understand correctly there is no easy workaround (nothing without hacking Netty 3 internals) As soon as we will declare 3.5.5 "stable" the world will hopefully abandon 3.4 and switch to 3.5 + Netty (because of SSL support). The network stack is very important so it is better to have Netty 4 as foundation, I am thinking about security issues, we won't make an "hotfix" release with the switch to Netty 4 because there is a bad bug in Netty 3. So better to switch now. But Facebooks friends, expecially @ivmaykov did a lot of bugfixes around Netty on master branch, we must be sure that what we are delivering in 3.5.5 is stable. We will also have to state clearly in the "release notes" that Netty version is changed, as this may have a non trivial impact to memory usage (i.e. Netty 4 uses more Direct memory by default) So to recap my final opinion: +1 to switch to Netty 4 if we take care of port all of the fixes around Netty 4 from master branch and we state the switch clearly in the release notes Enrico > > Regards, > Andor > > > > > >
