nomad.nomad.plan.queue_depth metric missing

[clobrox]

Nomad version

Nomad v1.3.6-zd84215+ent (fe6f9f9ed302ea13fffa4417375d2b89824a6ea8)

Issue

We no longer get the nomad.nomad.plan.queue_depth metric since our upgrade from 1.2.6+ent.

I believe the bug was introduced here:

https://github.com/hashicorp/nomad/pull/11983/files#diff-e76df9f1d1a93123add63e2828b97cbf4d55bd7fa0c42bb97d788bfe2fb598d0

In nomad/plan_queue.go we are missing a call to timer.Reset(period).

It is also not clear to me if calls to https://pkg.go.dev/time#Timer.Reset are being done safely. From those docs: "For a Timer created with NewTimer, Reset should be invoked only on stopped or expired timers with drained channels."

I do not completely understand why this has led to us not seeing the metric, as I'd have expected to still get a single point when the process started, even if the timer was not reset.

[github-actions]

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