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https://issues.apache.org/jira/browse/BEAM-13782?focusedWorklogId=718837&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-718837
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ASF GitHub Bot logged work on BEAM-13782:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 01/Feb/22 17:20
Start Date: 01/Feb/22 17:20
Worklog Time Spent: 10m
Work Description: kennknowles commented on pull request #16680:
URL: https://github.com/apache/beam/pull/16680#issuecomment-1027093278
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Issue Time Tracking
-------------------
Worklog Id: (was: 718837)
Time Spent: 0.5h (was: 20m)
> NPE
> ----
>
> Key: BEAM-13782
> URL: https://issues.apache.org/jira/browse/BEAM-13782
> Project: Beam
> Issue Type: Bug
> Components: sdk-java-core
> Affects Versions: 2.35.0
> Reporter: Kellen Dye
> Priority: P2
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> Discussed here:
> [https://lists.apache.org/thread/rcto0yggqygfk0ljnd8mg69h83rhvvs5]
>
> ---
>
> We (Spotify) are experiencing flaky tests on beam 2.35.0 as a result of
> NullPointerExceptions during pipeline construction.
>
> Stacktrace [1]. Root cause appears to be multiple threads accessing
> DeserializationContext from ValueProvider.Deserializer.deserialize [2] which,
> according to the javadocs "is guaranteed to only be used from single-threaded
> context" [3]
>
> In the context internals, the mutable _currentType is set [4] then accessed a
> few lines later [5], but in a multithreaded situation the writes clobber each
> other and a call to next() can fail with a NPE.
>
> I think synchronizing on ctxt in [2] should be sufficient to avoid this
> issue, but I'm not sure if the NPEs are due to beam misuse or something on
> the jackson side that should be changed.
>
> Failing (scala) test here, scalatest runs tests in parallel:
> [https://gist.github.com/kellen/124185463c16a66167a7fa704147c510#file-fail-scala]
>
> Test stacktrace:
> [https://gist.github.com/kellen/124185463c16a66167a7fa704147c510#file-test_stacktrace-txt]
>
> [1]
> [https://gist.github.com/kellen/124185463c16a66167a7fa704147c510#file-stacktrace-txt]
> [2]
> [https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/options/ValueProvider.java#L359]
> [3]
> [https://github.com/joansmith/jackson-databind/blob/master/src/main/java/com/fasterxml/jackson/databind/DeserializationContext.java#L36]
> [4]
> [https://github.com/joansmith/jackson-databind/blob/master/src/main/java/com/fasterxml/jackson/databind/DeserializationContext.java#L652]
> [5]
> [https://github.com/joansmith/jackson-databind/blob/master/src/main/java/com/fasterxml/jackson/databind/DeserializationContext.java#L656]
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