fix: Propagate stop channel to prevent resource leaks in VPA components

[omerap12]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Fixes potential resource leaks and improves shutdown handling in VPA components by properly propagating stop channels. Previously, some components were creating their own stop channels which could lead to improper cleanup during shutdown. Adds proper cache synchronization checks.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

NONE

[voelzmo]

I'm curious, did you observe any actual issues with the current implementation? Can you help me understand which error scenario this change covers?

My understanding is that if the run method only ever terminates on a fatal/os.Exit, which would in theory also tear down all the other routines as well?

[omerap12]

I'm curious, did you observe any actual issues with the current implementation? Can you help me understand which error scenario this change covers?

My understanding is that if the run method only ever terminates on a fatal/os.Exit, which would in theory also tear down all the other routines as well?

I didn't observe any specific issues, and you're mostly correct. but, for graceful shutdowns (e.g., during rolling updates or controlled scaling down), it's better to ensure proper cleanup. By adding WaitForCacheSync in the newPodClients function, we ensure that the cache is fully synchronized before the lister starts being used. Without this check, there's a potential race condition where the lister might be used before its cache is fully populated.

[voelzmo]

Thanks for helping me understand! I guess we can make a mental note to switch this to context instead of using stop channels once client-go 0.33.0 has been tagged: kubernetes/client-go@5d289bc#diff-dbac68d65bbc9814c2336df6ee91f22e807d84a9127a4d34a8b39c5657d0e447R369

[voelzmo]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: omerap12, voelzmo

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[omerap12]

Thanks for helping me understand! I guess we can make a mental note to switch this to context instead of using stop channels once client-go 0.33.0 has been tagged: kubernetes/client-go@5d289bc#diff-dbac68d65bbc9814c2336df6ee91f22e807d84a9127a4d34a8b39c5657d0e447R369

I agree. Ill open an issue so we won't forget about this :)

[adrianmoisey]

/lgtm