Matthias created FLINK-21376:
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Summary: Failed state might not provide failureCause
Key: FLINK-21376
URL: https://issues.apache.org/jira/browse/FLINK-21376
Project: Flink
Issue Type: Bug
Components: Runtime / Task
Affects Versions: 1.12.1
Reporter: Matthias
Fix For: 1.13.0
{{Task.executionState}} and {{Task.failureCause}} are not set atomically. This
became an issue when implementing the exception history (FLINK-21187) where we
relied on the invariant that a {{failureCause}} is present when the {{Task}}
failed.
Adding this check to
[Task.notifyFinalStage()|https://github.com/apache/flink/blob/9b6f076a66970d3d3ef710f8d5ee66d75d87eba5/flink-runtime/src/main/java/org/apache/flink/runtime/taskmanager/Task.java#L1001]
will reveal the race condition.
{{TaskExecutorSlotLifetimeTest}} becomes unstable when adding this invariant.
The reason is that the test starts a task but does not wait for the task to be
finished. The [task
finalization|https://github.com/apache/flink/blob/9b6f076a66970d3d3ef710f8d5ee66d75d87eba5/flink-runtime/src/main/java/org/apache/flink/runtime/taskmanager/Task.java#L895]
and [the cancellation of the
task|https://github.com/apache/flink/blob/9b6f076a66970d3d3ef710f8d5ee66d75d87eba5/flink-runtime/src/main/java/org/apache/flink/runtime/taskmanager/Task.java#L1105]
triggered through stopping the {{TaskManager}} shutdown compete with each
other and could cause the {{executionState}} to be set to {{FAILED}} while the
{{failureCause}} still being {{null}}. This is then forwarded to {{Execution}}
through
[Task.notifyFinalState|https://github.com/apache/flink/blob/9b6f076a66970d3d3ef710f8d5ee66d75d87eba5/flink-runtime/src/main/java/org/apache/flink/runtime/taskmanager/Task.java#L895].
We should set {{failureCause}} while setting the {{executionState}} to failed
to not miss any caught error.
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