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https://issues.apache.org/jira/browse/FLINK-7388?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16196370#comment-16196370
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ASF GitHub Bot commented on FLINK-7388:
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GitHub user bowenli86 opened a pull request:
https://github.com/apache/flink/pull/4786
[FLINK-7388][DataStream API] ProcessFunction.onTimer() sets processing time
as timestamp
## What is the purpose of the change
Before Flink 1.4.0, when called from a processing-time timer, the
`ProcessFunction.onTimer()` method sets the current processing time as
event-time timestamp. This behavior is very subtle and might not be noticed by
users.
Well, it's harmful because processing-time timestamps are indeterministic
and not aligned with watermarks. Besides, user-implemented logic depends on
this wrong timestamp highly likely is unintendedly faulty.
So we've decided to fix it. Upon upgrading to 1.4.0, Flink jobs that are
using this incorrect event-time timestamp will fail, and users should adapt
their jobs to the correct logic.
## Brief change log
- not set a timestamp for processing-time timer
## Verifying this change
This change is already covered by existing tests
## Does this pull request potentially affect one of the following parts:
None
## Documentation
- Does this pull request introduce a new feature? (no)
- If yes, how is the feature documented? (docs)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/bowenli86/flink FLINK-7388
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/4786.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #4786
----
commit 1fec305efba8ad94b7d7e72a672186caaf40270e
Author: Bowen Li <bowenl...@gmail.com>
Date: 2017-10-08T22:57:51Z
[FLINK-7388] ProcessFunction.onTimer() sets processing time as timestamp
commit 7e9afde7519381adadf222febea9640afd41fa2a
Author: Bowen Li <bowenl...@gmail.com>
Date: 2017-10-08T23:26:54Z
add doc
----
> ProcessFunction.onTimer() sets processing time as timestamp
> -----------------------------------------------------------
>
> Key: FLINK-7388
> URL: https://issues.apache.org/jira/browse/FLINK-7388
> Project: Flink
> Issue Type: Improvement
> Components: DataStream API
> Affects Versions: 1.4.0, 1.3.2
> Reporter: Fabian Hueske
> Assignee: Bowen Li
> Fix For: 1.4.0
>
>
> The {{ProcessFunction.onTimer()}} method sets the current processing time as
> event-time timestamp when it is called from a processing time timer.
> I don't think this behavior is useful. Processing time timestamps won't be
> aligned with watermarks and are not deterministic. The only reason would be
> to have _some_ value in the timestamp field. However, the behavior is very
> subtle and might not be noticed by users.
> IMO, it would be better to erase the timestamp. This will cause downstream
> operator that rely on timestamps to fail and notify the users that the logic
> they implemented was probably not what they intended to do.
> What do you think [~aljoscha]?
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