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https://issues.apache.org/jira/browse/SPARK-33737?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stavros Kontopoulos updated SPARK-33737:
----------------------------------------
Description:
Kubernetes backend uses Fabric8 client and a
[watch|https://github.com/apache/spark/blob/master/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsWatchSnapshotSource.scala#L42]
to monitor the K8s Api server for pod changes. Every watcher keeps a websocket
connection open and has no caching mechanism at that part. Caching exists in
other areas where hitting the Api Server for Pod CRUD ops like
[here|https://github.com/apache/spark/blob/b8ccd755244d3cd8a81a9f4a1eafa2a4e48759d2/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsLifecycleManager.scala#L49].
In an env where a lot of connections are kept due to large scale jobs this
could be problematic.
A lot of long running jobs should not create pod changes eg. Streaming jobs to
justify a continuous watching mechanism.
Latest Frabric8 client versions have implemented a SharedInformer API+Lister,
an example can be found
[here|https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/InformerExample.java#L37].
This new API follows the implementation of the official java K8s client and the
go counterpart and it is backed up by a caching mechanism which is resynced
after a configurble period. There is also a lister that keeps track of current
status of resources.
The suggestion is to update to v4.13.0 the client (has all updates in wrt that
API) and use the informer+lister API where applicable. I think the lister could
replace part of the snapshotting/notification mechanism.
/cc [~dongjoon] WDYTH?
was:
Kubernetes backend uses Fabric8 client and a
[watch|https://github.com/apache/spark/blob/master/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsWatchSnapshotSource.scala#L42]
to monitor the K8s Api server for pod changes. Every watcher keeps a websocket
connection open and has no caching mechanism at that part. Caching exists in
other areas where hitting the Api Server for Pod CRUD ops like
[here|https://github.com/apache/spark/blob/b8ccd755244d3cd8a81a9f4a1eafa2a4e48759d2/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsLifecycleManager.scala#L49].
In an env where a lot of connections are kept due to large scale jobs this
could be problematic.
A lot of long running jobs should not create pod changes eg. Streaming jobs to
justify a continuous watching mechanism.
Latest Frabric8 client versions have implemented a SharedInformer API+Lister,
an example can be found
[here|https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/InformerExample.java#L37].
This new API follows the implementation of the official java K8s client and the
go counterpart and it is backed up by a caching mechanism which is resynced
after a configurble period. There is also a lister that keeps track of current
status of resources.
The suggestion is to update to v4.13.0 the client (has all updates in wrt that
API) and use the informer+lister API where applicable. I think the lister could
replace part of the snapshotting/notification mechanism.
/cc [~erikerlandson] [~dongjoon] WDYTH?
> Use an Informer+Lister API in the ExecutorPodWatcher
> ----------------------------------------------------
>
> Key: SPARK-33737
> URL: https://issues.apache.org/jira/browse/SPARK-33737
> Project: Spark
> Issue Type: Improvement
> Components: Kubernetes
> Affects Versions: 3.0.2
> Reporter: Stavros Kontopoulos
> Priority: Major
>
> Kubernetes backend uses Fabric8 client and a
> [watch|https://github.com/apache/spark/blob/master/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsWatchSnapshotSource.scala#L42]
> to monitor the K8s Api server for pod changes. Every watcher keeps a
> websocket connection open and has no caching mechanism at that part. Caching
> exists in other areas where hitting the Api Server for Pod CRUD ops like
> [here|https://github.com/apache/spark/blob/b8ccd755244d3cd8a81a9f4a1eafa2a4e48759d2/resource-managers/kubernetes/core/src/main/scala/org/apache/spark/scheduler/cluster/k8s/ExecutorPodsLifecycleManager.scala#L49].
> In an env where a lot of connections are kept due to large scale jobs this
> could be problematic.
> A lot of long running jobs should not create pod changes eg. Streaming jobs
> to justify a continuous watching mechanism.
> Latest Frabric8 client versions have implemented a SharedInformer API+Lister,
> an example can be found
> [here|https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/InformerExample.java#L37].
> This new API follows the implementation of the official java K8s client and
> the go counterpart and it is backed up by a caching mechanism which is
> resynced after a configurble period. There is also a lister that keeps track
> of current status of resources.
> The suggestion is to update to v4.13.0 the client (has all updates in wrt
> that API) and use the informer+lister API where applicable. I think the
> lister could replace part of the snapshotting/notification mechanism.
> /cc [~dongjoon] WDYTH?
>
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