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Posted to issues@flink.apache.org by "yan zhou (JIRA)" <ji...@apache.org> on 2018/06/04 23:03:00 UTC
[jira] [Created] (FLINK-9524) NPE from
ProcTimeBoundedRangeOver.scala
yan zhou created FLINK-9524:
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Summary: NPE from ProcTimeBoundedRangeOver.scala
Key: FLINK-9524
URL: https://issues.apache.org/jira/browse/FLINK-9524
Project: Flink
Issue Type: Bug
Components: Table API & SQL
Affects Versions: 1.5.0
Reporter: yan zhou
Attachments: npe_from_ProcTimeBoundedRangeOver.txt
The class _ProcTimeBoundedRangeOver_ would throws NPE _minRetentionTime_ and _maxRetentionTime_ are set to greater then 1.
Please see [^npe_from_ProcTimeBoundedRangeOver.txt] for the detail of exception. Below is a short description the cause:
* When the first event for a key arrives, the cleanup time is registered with _timerservice_ and recorded in _cleanupTimeState_. If the second event with same key arrives before the cleanup time, the value in _cleanupTimeState_ is updated and a new timer is registered to _timerService_. So now we have two registered timers for cleanup. One is registered because of the first event, the other for the second event.
* However, when _onTimer_ method is fired for the first cleanup timer, the _cleanupTimeStates_ value has already been updated to second cleanup time. So it will bypass the _needToCleanupState_ check, and yet run through the remained code of _onTimer_ (which is intended to update the accumulator and emit output) and cause NPE.
_RowTimeBoundedRangeOver_ has very similar logic with _ProcTimeBoundedRangeOver. But_ It won't cause NPE by the same reason. To avoid the exception, it simply add a null check before running the logic for updating accumulator.
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