Il giorno lun 15 ott 2018 alle ore 12:46 Andor Molnar <[email protected]> ha scritto: > > Thank you guys. This is great help. > > I remember your efforts Bogdan, as far as I remember you observer thread > starvation in multiple runs on Apache Jenkins. Correct my if I’m wrong. > > I’ve created an umbrella Jira to capture all flaky test fixing efforts here: > https://issues.apache.org/jira/browse/ZOOKEEPER-3170 > <https://issues.apache.org/jira/browse/ZOOKEEPER-3170> > > All previous flaky-related tickets have been converted to sub-tasks. Some of > them might not be up-to-date, please consider reviewing them and close if > possible. Additionally feel free to create new sub-tasks to capture your > actual work. > > I’ve already modified Trunk and branch-3.5 builds to run on 4 threads for > testing initially. It resulted in slightly more stable tests:
+1 I have assigned the umbrella issue to you Andor as you are driving this important task. is is ok ? thank you Enrico > > Trunk (java 8) - failing 1/4 (since #229) - build time increased by 40-45% > Trunk (java 9) - failing 0/2 (since #993) - ~40% > Trunk (java 10) - failing 1/2 (since #280) - > branch-3.5 (java 8) - failing 0/4 (since #1153) - ~35-45% > > However the pattern is not big enough and results are inaccurate, so I need > more builds. I also need to fix a bug in SSL to get java9/10 builds working > on 3.5. > > Please let me know if I should revert the changes. Precommit build is still > running on 8 threads, but I’d like to change that one too. > > Regards, > Andor > > > > > On 2018. Oct 15., at 9:31, Bogdan Kanivets <[email protected]> wrote: > > > > Fangmin, > > > > Those are good ideas. > > > > FYI, I've stated running tests continuously in aws m1.xlarge. > > https://github.com/lavacat/zookeeper-tests-lab > > > > So far, I've done ~ 12 runs of trunk. Same common offenders as in Flaky > > dash: testManyChildWatchersAutoReset, testPurgeWhenLogRollingInProgress > > I'll do some more runs, then try to come up with report. > > > > I'm using aws and not Apache Jenkins env because of better > > control/observability. > > > > > > > > > > On Sun, Oct 14, 2018 at 4:58 PM Fangmin Lv <[email protected]> wrote: > > > >> Internally, we also did some works to reduce the flaky, here are the main > >> things we've done: > >> > >> * using retry rule to retry in case the zk client lost it's connection, > >> this could happen if the quorum tests is running on unstable environment > >> and the leader election happened. > >> * using random port instead of sequentially to avoid the port racing when > >> running tests concurrently > >> * changing tests to avoid using the same test path when creating/deleting > >> nodes > >> > >> These greatly reduced the flaky internally, we should try those if we're > >> seeing similar issues in the Jenkins. > >> > >> Fangmin > >> > >> On Sat, Oct 13, 2018 at 10:48 AM Bogdan Kanivets <[email protected]> > >> wrote: > >> > >>> I've looked into flakiness couple months ago (special attention on > >>> testManyChildWatchersAutoReset). In my opinion the problem is a) and c). > >>> Unfortunately I don't have data to back this claim. > >>> > >>> I don't remember seeing many 'port binding' exceptions. Unless 'port > >>> assignment' issue manifested as some other exception. > >>> > >>> Before decreasing number of threads I think more data should be > >>> collected/visualized > >>> > >>> 1) Flaky dashboard is great, but we should add another report that maps > >>> 'error causes' to builds/tests > >>> 2) Flaky dash can be extended to save more history (for example like this > >>> https://www.chromium.org/developers/testing/flakiness-dashboard) > >>> 3) PreCommit builds should be included in dashboard > >>> 4) We should have a common clean benchmark. For example - take > >>> AWS t3.xlarge instance with set linux distro, jvm, zk commit sha and run > >>> tests (current 8 threads) for 8 hours with 1 min cooldown. > >>> > >>> Due to recent employment change, I got sidetracked, but I really want to > >>> get to the bottom of this. > >>> I'm going to setup 4) and report results to this mailing list. Also > >> willing > >>> to work on other items. > >>> > >>> > >>> > >>> > >>> > >>> > >>> On Sat, Oct 13, 2018 at 4:59 AM Enrico Olivelli <[email protected]> > >>> wrote: > >>> > >>>> Il ven 12 ott 2018, 23:17 Benjamin Reed <[email protected]> ha scritto: > >>>> > >>>>> i think the unique port assignment (d) is more problematic than it > >>>>> appears. there is a race between finding a free port and actually > >>>>> grabbing it. i think that contributes to the flakiness. > >>>>> > >>>> > >>>> This is very hard to solve for our test cases, because we need to build > >>>> configs before starting the groups of servers. > >>>> For tests in single server it will be easier, you just have to start > >> the > >>>> server on port zero, get the port and the create client configs. > >>>> I don't know how much it will be worth > >>>> > >>>> Enrico > >>>> > >>>> > >>>>> ben > >>>>> On Fri, Oct 12, 2018 at 8:50 AM Andor Molnar <[email protected]> > >> wrote: > >>>>>> > >>>>>> That is a completely valid point. I started to investigate flakies > >>> for > >>>>> exactly the same reason, if you remember the thread that I started a > >>>> while > >>>>> ago. It was later abandoned unfortunately, because I’ve run into a > >> few > >>>>> issues: > >>>>>> > >>>>>> - We nailed down that in order to release 3.5 stable, we have to > >> make > >>>>> sure it’s not worse than 3.4 by comparing the builds: but these > >> builds > >>>> are > >>>>> not comparable, because 3.4 tests running single threaded while 3.5 > >>>>> multithreaded showing problems which might also exist on 3.4, > >>>>>> > >>>>>> - Neither of them running C++ tests for some reason, but that’s not > >>>>> really an issue here, > >>>>>> > >>>>>> - Looks like tests on 3.5 is just as solid as on 3.4, because > >> running > >>>>> them on a dedicated, single threaded environment show almost all > >> tests > >>>>> succeeding, > >>>>>> > >>>>>> - I think the root cause of failing unit tests could be one (or > >> more) > >>>> of > >>>>> the following: > >>>>>> a) Environmental: Jenkins slave gets overloaded with other > >>>>> builds and multithreaded test running makes things even worse: > >> starving > >>>> JDK > >>>>> threads and ZK instances (both clients and servers) are unable to > >>> operate > >>>>>> b) Conceptional: ZK unit tests were not designed to run on > >>>>> multiple threads: I investigated the unique port assignment feature > >>> which > >>>>> is looking good, but there could be other possible gaps which makes > >>> them > >>>>> unreliable when running simultaneously. > >>>>>> c) Bad testing: testing ZK in the wrong way, making bad > >>>>> assumption (e.g. not syncing clients), etc. > >>>>>> d) Bug in the server. > >>>>>> > >>>>>> I feel that finding case d) with these tests is super hard, > >> because a > >>>>> test report doesn’t give any information on what could go wrong with > >>>>> ZooKeeper. More or less guessing is your only option. > >>>>>> > >>>>>> Finding c) is a little bit easier, I’m trying to submit patches on > >>> them > >>>>> and hopefully making some progress. > >>>>>> > >>>>>> The huge pain in the arse though are a) and b): people desperately > >>> keep > >>>>> commenting “please retest this” on github to get a green build while > >>>>> testing is going in a direction to hide real problems: I mean people > >>>>> started not to care about a failing build, because “it must be some > >>> flaky > >>>>> unrelated to my patch”. Which is bad, but the shame is it’s true 90% > >>>>> percent of cases. > >>>>>> > >>>>>> I’m just trying to find some ways - besides fixing c) and d) > >> flakies > >>> - > >>>>> to get more reliable and more informative Jenkins builds. Don’t want > >> to > >>>>> make a huge turnaround, but I think if we can get a significantly > >> more > >>>>> reliable build for the price of slightly longer build time running > >> on 4 > >>>>> threads instead of 8, I say let’s do it. > >>>>>> > >>>>>> As always, any help from the community is more than welcome and > >>>>> appreciated. > >>>>>> > >>>>>> Thanks, > >>>>>> Andor > >>>>>> > >>>>>> > >>>>>> > >>>>>> > >>>>>>> On 2018. Oct 12., at 16:52, Patrick Hunt <[email protected]> > >> wrote: > >>>>>>> > >>>>>>> iirc the number of threads was increased to improve performance. > >>>>> Reducing > >>>>>>> is fine, but do we understand why it's failing? Perhaps it's > >>> finding > >>>>> real > >>>>>>> issues as a result of the artificial concurrency/load. > >>>>>>> > >>>>>>> Patrick > >>>>>>> > >>>>>>> On Fri, Oct 12, 2018 at 7:12 AM Andor Molnar > >>>>> <[email protected]> > >>>>>>> wrote: > >>>>>>> > >>>>>>>> Thanks for the feedback. > >>>>>>>> I'm running a few tests now: branch-3.5 on 2 threads and trunk > >> on > >>> 4 > >>>>> threads > >>>>>>>> to see what's the impact on the build time. > >>>>>>>> > >>>>>>>> Github PR job is hard to configure, because its settings are > >> hard > >>>>> coded > >>>>>>>> into a shell script in the codebase. I have to open PR for that. > >>>>>>>> > >>>>>>>> Andor > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> On Fri, Oct 12, 2018 at 2:46 PM, Norbert Kalmar < > >>>>>>>> [email protected]> wrote: > >>>>>>>> > >>>>>>>>> +1, running the tests locally with 1 thread always passes > >> (well, > >>> I > >>>>> run it > >>>>>>>>> about 5 times, but still) > >>>>>>>>> On the other hand, running it on 8 threads yields similarly > >> flaky > >>>>> results > >>>>>>>>> as Apache runs. (Although it is much faster, but if we have to > >>> run > >>>>> 6-8-10 > >>>>>>>>> times sometimes to get a green run...) > >>>>>>>>> > >>>>>>>>> Norbert > >>>>>>>>> > >>>>>>>>> On Fri, Oct 12, 2018 at 2:05 PM Enrico Olivelli < > >>>> [email protected] > >>>>>> > >>>>>>>>> wrote: > >>>>>>>>> > >>>>>>>>>> +1 > >>>>>>>>>> > >>>>>>>>>> Enrico > >>>>>>>>>> > >>>>>>>>>> Il ven 12 ott 2018, 13:52 Andor Molnar <[email protected]> ha > >>>>> scritto: > >>>>>>>>>> > >>>>>>>>>>> Hi, > >>>>>>>>>>> > >>>>>>>>>>> What do you think of changing number of threads running unit > >>>> tests > >>>>> in > >>>>>>>>>>> Jenkins from current 8 to 4 or even 2? > >>>>>>>>>>> > >>>>>>>>>>> Running unit tests inside Cloudera environment on a single > >>> thread > >>>>>>>> shows > >>>>>>>>>> the > >>>>>>>>>>> builds much more stable. That would be probably too slow, but > >>>> maybe > >>>>>>>>>> running > >>>>>>>>>>> at least less threads would improve the situation. > >>>>>>>>>>> > >>>>>>>>>>> It's getting very annoying that I cannot get a green build on > >>>>> GitHub > >>>>>>>>> with > >>>>>>>>>>> only a few retests. > >>>>>>>>>>> > >>>>>>>>>>> Regards, > >>>>>>>>>>> Andor > >>>>>>>>>>> > >>>>>>>>>> -- > >>>>>>>>>> > >>>>>>>>>> > >>>>>>>>>> -- Enrico Olivelli > >>>>>>>>>> > >>>>>>>>> > >>>>>>>> > >>>>>> > >>>>> > >>>> -- > >>>> > >>>> > >>>> -- Enrico Olivelli > >>>> > >>> > >> >
