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https://issues.apache.org/jira/browse/FLINK-5479?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16385863#comment-16385863
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ASF GitHub Bot commented on FLINK-5479:
---------------------------------------
GitHub user tzulitai opened a pull request:
https://github.com/apache/flink/pull/5634
[FLINK-5479] [kafka] Idleness detection for periodic per-partition
watermarks in FlinkKafkaConsumer
## What is the purpose of the change
This commit adds the capability to detect idle partitions in the
`FlinkKafkaConsumer` when using periodic per-partition watermark generation.
Users set the partition idle timeout using `setPartitionIdleTimeout(long)`. The
value of the timeout determines how long a an idle partition may block
watermark advancement downstream.
## Brief change log
- Adds a `setPartitionIdleTimeout(long)` configuration method
- Modifies `KafkaTopicPartitionStateWithPeriodicWatermarks` to keep track
of necessary information to determine partition idleness.
- Adds idleness detection logic to
`AsbtractFetcher.PeriodicWatermarkEmitter`.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (yes / **no**)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (yes / **no**)
- The serializers: (yes / **no** / don't know)
- The runtime per-record code paths (performance sensitive): (yes /
**no** / don't know)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / **no** / don't know)
- The S3 file system connector: (yes / **no** / don't know)
## Documentation
- Does this pull request introduce a new feature? (**yes** / no)
- If yes, how is the feature documented? (not applicable / docs /
**JavaDocs** / not documented)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/tzulitai/flink FLINK-5479
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/5634.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 #5634
----
commit d7b95ca1c8bb85f77dd6b83becf8fc1d5cccb810
Author: Tzu-Li (Gordon) Tai <tzulitai@...>
Date: 2018-03-05T09:35:02Z
[FLINK-5479] [kafka] Idleness detection for periodic per-partition
watermarks
This commit adds the capability to detect idle partitions in the
FlinkKafkaConsumer when using periodic per-partition watermark
generation. Users set the partition idle timeout using
`setPartitionIdleTimeout(long)`. The value of the timeout determines how
long a an idle partition may block watermark advancement downstream.
----
> Per-partition watermarks in FlinkKafkaConsumer should consider idle partitions
> ------------------------------------------------------------------------------
>
> Key: FLINK-5479
> URL: https://issues.apache.org/jira/browse/FLINK-5479
> Project: Flink
> Issue Type: Improvement
> Components: Kafka Connector
> Reporter: Tzu-Li (Gordon) Tai
> Priority: Blocker
> Fix For: 1.5.0
>
>
> Reported in ML:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Kafka-topic-partition-skewness-causes-watermark-not-being-emitted-td11008.html
> Similar to what's happening to idle sources blocking watermark progression in
> downstream operators (see FLINK-5017), the per-partition watermark mechanism
> in {{FlinkKafkaConsumer}} is also being blocked of progressing watermarks
> when a partition is idle. The watermark of idle partitions is always
> {{Long.MIN_VALUE}}, therefore the overall min watermark across all partitions
> of a consumer subtask will never proceed.
> It's normally not a common case to have Kafka partitions not producing any
> data, but it'll probably be good to handle this as well. I think we should
> have a localized solution similar to FLINK-5017 for the per-partition
> watermarks in {{AbstractFetcher}}.
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