This turned out to be a tricky bug. Robert and me had a joined debugging
session and managed to find the culprit.
PR pending: https://github.com/apache/beam/pull/7171
On 27.11.18 19:35, Kenneth Knowles wrote:
I actually didn't look at this one. I filed a bunch more adjacent flake
bugs. I didn't find your bug but I do see that test flaking at the same
time as the others. FWIW here is the list of flakes and sickbayed tests:
https://issues.apache.org/jira/issues/?filter=12343195
Kenn
On Tue, Nov 27, 2018 at 10:25 AM Alex Amato <[email protected]
<mailto:[email protected]>> wrote:
+Ken,
Did you happen to look into this test? I heard that you may have
been looking into this.
On Mon, Nov 26, 2018 at 3:36 PM Maximilian Michels <[email protected]
<mailto:[email protected]>> wrote:
Hi Alex,
Thanks for your help! I'm quite used to debugging
concurrent/distributed
problems. But this one is quite tricky, especially with regards
to GRPC
threads. I try to provide more information in the following.
There are two observations:
1) The problem is specifically related to how the cleanup is
performed
for the EmbeddedEnvironmentFactory. The environment is shutdown
when the
SDK Harness exists but the GRPC threads continue to linger for
some time
and may stall state processing on the next test.
If you do _not_ close DefaultJobBundleFactory, which happens during
close() or dispose() in the FlinkExecutableStageFunction or
ExecutableStageDoFnOperator respectively, the tests run just
fine. I ran
1000 test runs without a single failure.
The EmbeddedEnvironment uses direct channels which are marked
experimental in GRPC. We may have to convert them to regular socket
communication.
2) Try setting a conditional breakpoint in GrpcStateService
which will
never break, e.g. "false". Set it here:
https://github.com/apache/beam/blob/6da9aa5594f96c0201d497f6dce4797c4984a2fd/runners/java-fn-execution/src/main/java/org/apache/beam/runners/fnexecution/state/GrpcStateService.java#L134
The tests will never fail. The SDK harness is always shutdown
correctly
at the end of the test.
Thanks,
Max
On 26.11.18 19:15, Alex Amato wrote:
> Thanks Maximilian, let me know if you need any help. Usually
I debug
> this sort of thing by pausing the IntelliJ debugger to see
all the
> different threads which are waiting on various conditions. If
you find
> any insights from that, please post them here and we can try
to figure
> out the source of the stuckness. Perhaps it may be some
concurrency
> issue leading to deadlock?
>
> On Thu, Nov 22, 2018 at 12:57 PM Maximilian Michels
<[email protected] <mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
> I couldn't fix it thus far. The issue does not seem to be
in the Flink
> Runner but in the way the tests utilizes the EMBEDDED
environment to
> run
> multiple portable jobs in a row.
>
> When it gets stuck it is in RemoteBundle#close and it is
independent of
> the test type (batch and streaming have different
implementations).
>
> Will give it another look tomorrow.
>
> Thanks,
> Max
>
> On 22.11.18 13:07, Maximilian Michels wrote:
> > Hi Alex,
> >
> > The test seems to have gotten flaky after we merged
support for
> portable
> > timers in Flink's batch mode.
> >
> > Looking into this now.
> >
> > Thanks,
> > Max
> >
> > On 21.11.18 23:56, Alex Amato wrote:
> >> Hello, I have noticed
> >>
that org.apache.beam.runners.flink.PortableTimersExecutionTest
> is very
> >> flakey, and repro'd this test timeout on the master
branch in
> 40/50 runs.
> >>
> >> I filed a JIRA issue: BEAM-6111
> >> <https://issues.apache.org/jira/browse/BEAM-6111>. I
was just
> >> wondering if anyone knew why this may be occurring,
and to check if
> >> anyone else has been experiencing this.
> >>
> >> Thanks,
> >> Alex
>
