Update: still the root cause of is unknown.

>From my observation with debug logging and thread dump,
"grpc-default-executor-XXX" threads disappear when the problematic tests
become hung.
More notes: https://github.com/apache/beam/pull/14768#issuecomment-840228795

Interestingly the "grpc-default-executor-XXX" threads reappear in the logs
when the pause triggers a 5-second timeout set by JUnit.


On Tue, May 11, 2021 at 1:12 PM Tomo Suzuki <[email protected]> wrote:

> Thank you for the advice. Yes, the latch not being counted-down is the
> problem. (my memo:
> https://github.com/apache/beam/pull/14474#discussion_r619557479 ) I'll
> need to figure out why withOnError is not called.
>
>
> > Can you repro locally?
>
> No, the task succeeds in my environment (./gradlew
> :runners:google-cloud-dataflow-java:worker:test).
>
>
> On Tue, May 11, 2021 at 12:34 PM Kenneth Knowles <[email protected]> wrote:
>
>> I am not sure how much you read the code of the test. So apologies if I
>> am saying things you already know. The test does something like:
>>
>>  - start a logging service
>>  - set up some stub clients, each with onError wired up to release a
>> countdown latch
>>  - send error responses to all three of them (actually it sends the error
>> in the same task it creates the stub)
>>  - each task waits on the latch
>>
>> So if onError does not deliver or does not call to release the countdown
>> latch, it will hang. I notice in the gist you provide that all three stub
>> clients are hung awaiting the latch. That is suspicious to me. I would want
>> to confirm if the flakiness always occurs in a way that hangs all three.
>> Then there are gRPC workers waiting on empty queues, and the main test
>> thread waiting for the hung tasks to complete.
>>
>> The problem could be something about the test set up. Personally I would
>> add a ton of logs, or potentially use a debugger, to confirm exactly the
>> state of things when it hangs. Can you repro locally? I think this same
>> functionality could be tested in different ways that might remove some of
>> the variables. For example starting up all the waiting tasks, then sending
>> all the onError messages that should cause them to terminate.
>>
>> Since this is a unit test, adding a timeout to just that method should
>> save time (but will make it harder to capture stack traces, etc). I've
>> opened up https://github.com/apache/beam/pull/14781 for that. There may
>> be a nice way to add a timeout to the executor to capture the hung stack,
>> but I didn't look for it.
>>
>> Kenn
>>
>> On Tue, May 11, 2021 at 7:36 AM Tomo Suzuki <[email protected]> wrote:
>>
>>> gRPC 1.37.0 showed the same problem:
>>> BeamFnLoggingServiceTest.testMultipleClientsFailingIsHandledGracefullyByServer
>>> waits tasks forever, causing timeout in Java precommit.
>>>
>>> While I continue my investigation, I appreciate if someone knows the
>>> cause of the problem, I pasted the thread dump of the Java process when the
>>> test was frozen:
>>> https://github.com/apache/beam/pull/14768
>>>
>>> If this mystery is never solved, vendoring (a bit old) gRPC 1.32.2
>>> without the jboss dependencies is an alternate option, (suggestion by Kenn;
>>> memo
>>> <https://issues.apache.org/jira/browse/BEAM-11227?focusedCommentId=17318238&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17318238>
>>> )
>>>
>>> Regards,
>>> Tomo
>>>
>>>
>>> On Mon, May 10, 2021 at 9:40 AM Tomo Suzuki <[email protected]> wrote:
>>>
>>>> I was investigating the strange timeout (
>>>> https://github.com/apache/beam/pull/14474) but was occupied with
>>>> something else lately.
>>>> Let me try the new version today to see any improvements.
>>>>
>>>>
>>>> On Mon, May 10, 2021 at 4:57 AM Ismaël Mejía <[email protected]> wrote:
>>>>
>>>>> I just saw that gRPC 1.37.1 is out now (and with aarch64 support for
>>>>> python!) that made me wonder about this, what is the current status of
>>>>> upgrading the vendored dependency Tomo?
>>>>>
>>>>>
>>>>> On Thu, Apr 8, 2021 at 4:16 PM Tomo Suzuki <[email protected]> wrote:
>>>>>
>>>>>> We observed the cron job of Java Precommit for the master branch
>>>>>> started timing out often (not always) since upgrading the gRPC version.
>>>>>> https://github.com/apache/beam/pull/14466#issuecomment-815343974
>>>>>>
>>>>>> Exchanged messages with Kenn, I reverted to the change; now the
>>>>>> master branch uses the vendored gRPC 1.26.
>>>>>>
>>>>>>
>>>>>> On Wed, Mar 31, 2021 at 11:40 AM Kenneth Knowles <[email protected]>
>>>>>> wrote:
>>>>>>
>>>>>>> Merged. Let's keep an eye for trouble, and I will incorporate to the
>>>>>>> release branch.
>>>>>>>
>>>>>>> Kenn
>>>>>>>
>>>>>>> On Wed, Mar 31, 2021 at 6:45 AM Tomo Suzuki <[email protected]>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Regarding troubleshooting on build timeout, it seems that Docker
>>>>>>>> cache in Jenkins machines might be playing a role. As I run more "Java
>>>>>>>> Presubmit", I no longer observe timeouts in the PR.
>>>>>>>>
>>>>>>>> Kenn, would you merge the PR?
>>>>>>>> https://github.com/apache/beam/pull/14295 (all checks green,
>>>>>>>> including the new Java postcommit checks)
>>>>>>>>
>>>>>>>> On Thu, Mar 25, 2021 at 5:24 PM Kenneth Knowles <[email protected]>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> Yes, I agree this might be a good idea. This is not the only major
>>>>>>>>> issue on the release-2.29.0 branch.
>>>>>>>>>
>>>>>>>>> The counter argument is that we will be pulling in all the bugs
>>>>>>>>> introduced to `master` since the branch cut.
>>>>>>>>>
>>>>>>>>> As far as effort goes, I have been mostly focused on burning down
>>>>>>>>> the bugs so I would not lose much work in the release process.
>>>>>>>>>
>>>>>>>>> Kenn
>>>>>>>>>
>>>>>>>>> On Thu, Mar 25, 2021 at 1:42 PM Ismaël Mejía <[email protected]>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> Precommit is quite unstable in the last days, so worth to check if
>>>>>>>>>> something is wrong in the CI.
>>>>>>>>>>
>>>>>>>>>> I have a question Kenn. Given that cherry picking this might be a
>>>>>>>>>> bit
>>>>>>>>>> big as a change can we just reconsider cutting the 2.29.0 branch
>>>>>>>>>> again
>>>>>>>>>> after the updated gRPC version use gets merged and mark the issues
>>>>>>>>>> already fixed for version 2.30.0 to version 2.29.0 ? Seems like an
>>>>>>>>>> easier upgrade path (and we will get some nice fixes/improvements
>>>>>>>>>> like
>>>>>>>>>> official Spark 3 support for free on the release).
>>>>>>>>>>
>>>>>>>>>> WDYT?
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Wed, Mar 24, 2021 at 8:06 PM Tomo Suzuki <[email protected]>
>>>>>>>>>> wrote:
>>>>>>>>>> >
>>>>>>>>>> > Update: I observe that Java precommit check is unstable in the
>>>>>>>>>> PR to upgrade vendored gRPC (compared with an PR with an empty 
>>>>>>>>>> change).
>>>>>>>>>> There's no constant failures; sometimes it succeeds and other times 
>>>>>>>>>> it
>>>>>>>>>> faces timeout and flaky test failures.
>>>>>>>>>> >
>>>>>>>>>> >
>>>>>>>>>> https://github.com/apache/beam/pull/14295#issuecomment-806071087
>>>>>>>>>> >
>>>>>>>>>> >
>>>>>>>>>> > On Mon, Mar 22, 2021 at 10:46 AM Tomo Suzuki <
>>>>>>>>>> [email protected]> wrote:
>>>>>>>>>> >>
>>>>>>>>>> >> Thank you for the voting and I see the artifact available in
>>>>>>>>>> Maven Central. I'll work on the PR to use the published artifact 
>>>>>>>>>> today.
>>>>>>>>>> >>
>>>>>>>>>> https://search.maven.org/artifact/org.apache.beam/beam-vendor-grpc-1_36_0/0.1/jar
>>>>>>>>>> >>
>>>>>>>>>> >> On Tue, Mar 16, 2021 at 3:07 PM Kenneth Knowles <
>>>>>>>>>> [email protected]> wrote:
>>>>>>>>>> >>>
>>>>>>>>>> >>> Update on this: there are some minor issues and then I'll
>>>>>>>>>> send out the RC.
>>>>>>>>>> >>>
>>>>>>>>>> >>> I think this is worth blocking 2.29.0 release on, so I will
>>>>>>>>>> do this first. We are still eliminating other blockers from 2.29.0 
>>>>>>>>>> anyhow.
>>>>>>>>>> >>>
>>>>>>>>>> >>> Kenn
>>>>>>>>>> >>>
>>>>>>>>>> >>> On Mon, Mar 15, 2021 at 7:17 AM Tomo Suzuki <
>>>>>>>>>> [email protected]> wrote:
>>>>>>>>>> >>>>
>>>>>>>>>> >>>> Hi Beam developers,
>>>>>>>>>> >>>>
>>>>>>>>>> >>>> I'm working on upgrading the vendored gRPC 1.36.0
>>>>>>>>>> >>>> https://issues.apache.org/jira/browse/BEAM-11227 (PR:
>>>>>>>>>> https://github.com/apache/beam/pull/14028)
>>>>>>>>>> >>>> Let me know if you have any questions or concerns.
>>>>>>>>>> >>>>
>>>>>>>>>> >>>> Background:
>>>>>>>>>> >>>> Exchanged messages with Ismaël in BEAM-11227, it seems that
>>>>>>>>>> it the ticket created by some automation is false positive, but it's 
>>>>>>>>>> nice
>>>>>>>>>> to use an artifact without being marked with CVE.
>>>>>>>>>> >>>>
>>>>>>>>>> >>>> Kenn offered to work as the release manager (as in
>>>>>>>>>> https://s.apache.org/beam-release-vendored-artifacts) of the
>>>>>>>>>> vendored artifact.
>>>>>>>>>> >>>>
>>>>>>>>>> >>>> --
>>>>>>>>>> >>>> Regards,
>>>>>>>>>> >>>> Tomo
>>>>>>>>>> >>
>>>>>>>>>> >>
>>>>>>>>>> >>
>>>>>>>>>> >> --
>>>>>>>>>> >> Regards,
>>>>>>>>>> >> Tomo
>>>>>>>>>> >
>>>>>>>>>> >
>>>>>>>>>> >
>>>>>>>>>> > --
>>>>>>>>>> > Regards,
>>>>>>>>>> > Tomo
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Regards,
>>>>>>>> Tomo
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>> --
>>>>>> Regards,
>>>>>> Tomo
>>>>>>
>>>>>
>>>>
>>>> --
>>>> Regards,
>>>> Tomo
>>>>
>>>
>>>
>>> --
>>> Regards,
>>> Tomo
>>>
>>
>
> --
> Regards,
> Tomo
>


-- 
Regards,
Tomo

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