Autoscaling reaction time is slow

[arschles]

If you create a new app and run this command with hey:

hey -n 2000000 -c 1000 ${APP_IP_OR_DOMAIN}

You'll see that it takes a while for KEDA to make a request to the GetMetrics external scaler endpoint, and so it takes a bit of time to scale up.

Expected Behavior

Application pods should scale up much faster.

Actual Behavior

Application pods can take 10s of seconds to scale up.

Steps to Reproduce the Problem

1. Create a new HTTPScaledObject
2. Get the IP of your new app (kubectl get svc -n $NAMESPACE, and copy the public IP from the LoadBalancer service)
3. Use the hey command above
4. Watch the app pods as they very slowly scale up

Note: you can speed this process way up if you set the pollingInterval to 1 on the ScaledObject. In most cases, you can get sub-second scale-up times. The cost of that is that you have KEDA polling the external scaler every 1ms. Surely there's a better way - maybe to use StreamIsActive more intelligently from the external scaler.

Specifications

N/A

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[arschles]

Autoscaling reaction time (especially from 0) has been sped up with #206. Closing