wangyang0918 opened a new pull request #15480:
URL: https://github.com/apache/flink/pull/15480
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## What is the purpose of the change
Flink now could only run 20 jobs or less in a K8s session(native and
standalone) when K8s HA enabled.
The root cause is fabric8 Kubernetes client has configured the MaxRequests
of `OkHttpClient#Dispatcher`[1] to 64[2], which means we could not create more
than 64 watchers in the JobManager pod.
Normally, it could be configured in Flink via env or java opts.
Unfortunately, the fabric8 Kubernetes client version 4.9.2 has a bug[3], which
causes the max concurrent requests could not be set via system properties.
This PR is a temporary fix before we bumping the fabric8 Kubernetes version
to 4.13.0+ or change the behavior how we watch the leader ConfigMaps.
After this commit, users could use any one in the following Flink config
options to set the concurrent max requests, which allows to run more jobs in a
session cluster. Please note that, each Flink job will consume 3 concurrent
requests.
* `containerized.master.env.KUBERNETES_MAX_CONCURRENT_REQUESTS: 200`
* `env.java.opts.jobmanager: "-Dkubernetes.max.concurrent.requests=200"`
1.
https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-client/src/main/java/io/fabric8/kubernetes/client/utils/HttpClientUtils.java#L166
2.
https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-client/src/main/java/io/fabric8/kubernetes/client/Config.java#L135
3. https://github.com/fabric8io/kubernetes-client/issues/2531
## Brief change log
* Support to configure max concurrent requests for fabric8 Kubernetes client
via JAVA opts or envs
## Verifying this change
* Add two unit tests
## 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, Kubernetes/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)
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