Looks like the burst configuration for the Workflow Controller doesn't actually do anything

[Radolumbo]

Was hunting down what burst actually does for https://cloud-native.slack.com/archives/C01QW9QSSSK/p1651410938829379

Looking for burst in https://github.com/argoproj/argo-workflows takes us to https://github.com/argoproj/argo-workflows/blob/master/workflow/controller/config.go#L85

Looks like it's using a built in golang Library, time/rate .. so we can take a look at https://pkg.go.dev/golang.org/x/time/rate#Limiter.Burst

This tells us

Burst returns the maximum burst size. Burst is the maximum number of tokens that can be consumed in a single call to Allow, Reserve, or Wait, so higher Burst values allow more events to happen at once. A zero Burst allows no events, unless limit == Inf.

Interesting. Where are we using any of those calls in the Workflow controller on this rateLimiter object from the first link? Looks like .. here

https://github.com/argoproj/argo-workflows/blob/master/workflow/controller/workflowpod.go#L429

So, we're using Allow. Based on

https://pkg.go.dev/golang.org/x/time/rate#Limiter.Allow

Allow is shorthand for AllowN(time.Now(), 1).

So wait -- burst tells us how many tokens for rate limiting can be requested in a single call to Allow. However, the controller only ever requests a single token at time.

Thus -- I actually think that the configured burst for the Workflow Controller doesn't do anything at all.

Let me know if it seems like I missed anything here, but I'm pretty sure burst does nothing for the Workflow controller.

[alexec]

This bug is correct. Yet, I don't think we can change the code to use AllowN, createWorkflowPod does not know how many pods will be created.

[Radolumbo]

Sure, I totally agree -- not suggesting we try to add that functionality, but rather we should probably clear out code/guidance that is confusing to users. Maybe I can take a crack at some point soon.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. If this is a mentoring request, please provide an update here. Thank you for your contributions.

[stale]

This issue has been closed due to inactivity. Feel free to re-open if you still encounter this issue.

[thor]

Coming across this by chance, I suggest re-opening this issue and marking it as frozen.