GitHub user NicoK opened a pull request:
https://github.com/apache/flink/pull/5790
[FLINK-9107][docs] document timer coalescing for ProcessFunction
## What is the purpose of the change
In a ProcessFunction, registering timers for each event via
`ctx.timerService().registerEventTimeTimer()` using timestamps like
`ctx.timestamp() + timeout` will get a millisecond accuracy and may thus create
one timer per millisecond which may lead to some overhead in the `TimerService`.
This problem can be mitigated by using timer coalescing if the desired
accuracy of the timer can be larger than 1ms. A timer firing at full seconds
only, for example, can be realised like this:
```
long coalescedTime = ((ctx.timestamp() + timeout) / 1000) * 1000;
ctx.timerService().registerEventTimeTimer(coalescedTime);
```
As a result, only a single timer may exist for every second since we do not
add timers for timestamps that are already there.
Please note that this PR includes #5788 and should also be merged into 1.3
and 1.4 docs to which it applies as well.
## Brief change log
- document timer coalescing for `ProcessFunction`
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/NicoK/flink flink-9107
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/5790.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 #5790
----
commit b6258697aabb8688aac19b5b228ddf8926e518f3
Author: Nico Kruber <nico@...>
Date: 2018-03-29T13:55:47Z
[FLINK-9110][docs] fix local bundler installation
commit 540485a5620f6dcdd98e751a086076fb80997f65
Author: Nico Kruber <nico@...>
Date: 2018-03-29T13:56:23Z
[hotfix][docs] remove duplicate bundle installation
commit f8274cf3ba06af19a4ac31e784803723e449336a
Author: Nico Kruber <nico@...>
Date: 2018-03-29T14:20:00Z
[FLINK-9107][docs] document timer coalescing for ProcessFunction
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