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HPA controller sends unecessary updates #47077

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DirectXMan12 opened this issue Jun 6, 2017 · 5 comments
Closed

HPA controller sends unecessary updates #47077

DirectXMan12 opened this issue Jun 6, 2017 · 5 comments
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kind/bug Categorizes issue or PR as related to a bug. sig/autoscaling Categorizes an issue or PR as relevant to SIG Autoscaling.

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@DirectXMan12
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BUG: the HPA controller submits updates every update interval, even if nothing has changed. In clusters with large numbers of HPAs, as well as clusters with smaller HPA sync periods, this can cause an unnecessarily high volume of writes.

The HPA controller should only send updates if it actually has a change to the HPA status object.
@DirectXMan12
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cc @kubernetes/sig-autoscaling-bugs @derekwaynecarr

@k8s-ci-robot k8s-ci-robot added sig/autoscaling Categorizes an issue or PR as relevant to SIG Autoscaling. kind/bug Categorizes issue or PR as related to a bug. labels Jun 6, 2017
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@DirectXMan12 There are no sig labels on this issue. Please add a sig label by:
(1) mentioning a sig: @kubernetes/sig-<team-name>-misc
(2) specifying the label manually: /sig <label>

Note: method (1) will trigger a notification to the team. You can find the team list here and label list here

@k8s-github-robot k8s-github-robot added needs-sig Indicates an issue or PR lacks a `sig/foo` label and requires one. and removed needs-sig Indicates an issue or PR lacks a `sig/foo` label and requires one. labels Jun 6, 2017
@DirectXMan12 DirectXMan12 mentioned this issue Jun 6, 2017
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@fgrzadkowski
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@DirectXMan12 Aren't we always updating 'observedGeneration' field?

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@fgrzadkowski we don't actually seem to do anything with that field. There's nothing in the HPA controller about it.

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/assign @DirectXMan12

k8s-github-robot pushed a commit that referenced this issue Jun 8, 2017
Merge pull request #47078 from DirectXMan12/bug/only-update-when-needed
6e8d6ac 
Automatic merge from submit-queue (batch tested with PRs 46979, 47078, 47138, 46916)

HPA: only send updates when the status has changed

This commit only sends updates if the status has actually changed.
Since the HPA runs at a regular interval, this should reduce the volume
of writes, especially on short HPA intervals with relatively constant
metrics.

Fixes #47077

**Release note**:
```release-note
The HorizontalPodAutoscaler controller will now only send updates when it has new status information, reducing the number of writes caused by the controller.
```
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