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For scaling deployments in particular, use a direct object get rather than the /scale API #1458

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merged 7 commits into from
Jan 6, 2021

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@coderanger coderanger commented Dec 28, 2020

So that it can use the informer cache for better performance.

This is annoying as a special case but is so common and improves performance so much that I think it's worthwhile to include. Another option would be to majorly increase the QPS rate limit on the scaling API client however that would also increase kube-apiserver load while watches/informers are generally much less impactful.

Checklist

  • Commits are signed with Developer Certificate of Origin (DCO)
  • Tests have been added
  • A PR is opened to update the documentation on https://github.com/kedacore/keda-docs
  • Changelog has been updated

Refs #1449

… than the /scale API so that it can use the informer cache for better performance.

This is annoying as a special case but is so common and improves performance so much that I think it's worthwhile to include. Another option would be to majorly increase the QPS rate limit on the scaling API client however that would also increase kube-apiserver load while watches/informers are generally much less impactful.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>
Signed-off-by: Noah Kantrowitz <noah@coderanger.net>
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Looking good, just a minor nit.

pkg/scaling/executor/scale_scaledobjects.go Outdated Show resolved Hide resolved
Also adds support for StatefulSets for symmetry.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>
pkg/scaling/executor/scale_scaledobjects.go Outdated Show resolved Hide resolved
pkg/scaling/executor/scale_scaledobjects.go Outdated Show resolved Hide resolved
pkg/scaling/executor/scale_scaledobjects.go Outdated Show resolved Hide resolved
pkg/scaling/executor/scale_scaledobjects.go Outdated Show resolved Hide resolved
switch {
case targetGVKR.Group == "apps" && targetGVKR.Kind == "Deployment":
deployment := &appsv1.Deployment{}
err := e.client.Get(ctx, client.ObjectKey{Name: targetGVKR.Resource, Namespace: scaledObject.Namespace}, deployment)
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targetName := scaledObject.Spec.ScaleTargetRef.Name

...

Suggested change
err := e.client.Get(ctx, client.ObjectKey{Name: targetGVKR.Resource, Namespace: scaledObject.Namespace}, deployment)
err := e.client.Get(ctx, client.ObjectKey{Name: targetName, Namespace: scaledObject.Namespace}, deployment)

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Seems weird to use different data sources, increased chance of them being out of sync?

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@zroubalik zroubalik Jan 6, 2021

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ScaledObject and the target workload should be always in the sync (the same namespace, if you are asking for this). But in your original code, I don't understand the intention, how do you want to guess the name from targetGVKR.Resource?

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I completely misunderstood this code, you are correct :)

currentReplicas = *deployment.Spec.Replicas
case targetGVKR.Group == "apps" && targetGVKR.Kind == "StatefulSet":
statefulSet := &appsv1.StatefulSet{}
err := e.client.Get(ctx, client.ObjectKey{Name: targetGVKR.Resource, Namespace: scaledObject.Namespace}, statefulSet)
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targetName := scaledObject.Spec.ScaleTargetRef.Name

...

Suggested change
err := e.client.Get(ctx, client.ObjectKey{Name: targetGVKR.Resource, Namespace: scaledObject.Namespace}, statefulSet)
err := e.client.Get(ctx, client.ObjectKey{Name: targetName, Namespace: scaledObject.Namespace}, statefulSet)

Co-authored-by: Zbynek Roubalik <726523+zroubalik@users.noreply.github.com>

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>
Co-authored-by: Zbynek Roubalik <726523+zroubalik@users.noreply.github.com>

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>
@zroubalik zroubalik merged commit 68a479c into kedacore:main Jan 6, 2021
ycabrer pushed a commit to ycabrer/keda that referenced this pull request Mar 1, 2021
… than the /scale API (kedacore#1458)

* For scaling deployments in particular, use a direct object get rather than the /scale API so that it can use the informer cache for better performance.

This is annoying as a special case but is so common and improves performance so much that I think it's worthwhile to include. Another option would be to majorly increase the QPS rate limit on the scaling API client however that would also increase kube-apiserver load while watches/informers are generally much less impactful.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Update changelog.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Use the already-normalized GVKR data so less weird string parsing.

Also adds support for StatefulSets for symmetry.

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Apply suggestions from code review

Co-authored-by: Zbynek Roubalik <726523+zroubalik@users.noreply.github.com>

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>

* Apply suggestions from code review

Co-authored-by: Zbynek Roubalik <726523+zroubalik@users.noreply.github.com>

Signed-off-by: Noah Kantrowitz <noah@coderanger.net>
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2 participants