Ticker leak in weighted round robin picker creation

[atollena]

What version of gRPC are you using?

1.57 (I believe the bug is still present on master)

What version of Go are you using (go version)?

1.21.0

What operating system (Linux, Windows, …) and version?

Linux

What did you do?

I am using the weighted_round_robin balancer via service config.

I have servers set with MaxConnectionAge to 5 minutes as to force DNS re-resolultion per #1663 (comment).

What did you expect to see?

CPU and memory usage stays constant.

What did you see instead?

The CPU usage and memory used by the application keeps growing.

[atollena]

Thanks to @HippoBaro for discovering this problem and the initial investigation.

I think the bug is just that this ticker:

grpc-go/balancer/weightedroundrobin/balancer.go

Lines 370 to 379 in 61a1f77

	go func() {
	ticker := time.NewTicker(time.Duration(p.cfg.WeightUpdatePeriod))
	for {
	select {
	case <-ctx.Done():
	return
	case <-ticker.C:
	p.regenerateScheduler()
	}
	}

is not properly closed. Suggested fix: #6643.

[easwars]

I hate the Ticker. This is the not the first time I'm seeing it cause a memory leak and probably wont be the last time either.

[atollena]

Yes, ideally there should be a vet rule for this.

[easwars]

Fixed by #6643.