@minux, while true, runtime/trace seems like a pretty high overhead way to collect what amounts to a fairly small amount of information. It's certainly low overhead for what it does, but what it does is much more than what's needed here. The metrics @deft-code wants are primarily intended for continuous monitoring (based on offline conversations), so it needs to be cheap.

Here are the notes on the desired metrics I had from our meeting a while ago:

Ring buffer of sampled duration between entering and exiting runnable state

• With some probability, when a goroutine enters runnable, tag it, and when it exits runnable, add the runnable duration to a ring
• Consumers can do what they want with these samples, including just averaging them, or building distributions.

Four global stats

• Current number of goroutines
• Total number of goroutines ever created
• Current number of runnable goroutines
• Total number of runnable-to-running transitions

Maybe current number of running goroutines

Assigning to @aclements to decide what we're willing to support long-term.

Ping @aclements

Still up to @aclements.

Ping @aclements. Can you look at this during the release candidate quiet?

@deft-code, do the specific stats I suggested in #15490 (comment) address your needs?

Sorry, I'd lost track of the fact that there was a concrete proposal doc for this: https://github.com/deft-code/proposal/blob/master/design/15490-schedstats.md

@deft-code, could you mail a CL to add this to the go-proposal repository and, once submitted, edit your first post to link to it? Thanks.

I'll get on top of it.

Thanks!

CL https://golang.org/cl/38180 mentions this issue.

Do we need to keep this issue open, or should we accept it?

There's definitely still work to do on how and what exactly the API should expose, but I think it's pretty clear we need to provide some visibility into the scheduler.

Teams inside Google are patching in CL 38180 and getting some experience with it. If others would like to do the same, please do. We'll probably wait until Go 1.10 to decide to add the API officially. Putting the proposal on hold until then.

@golang/runtime @mknyszek Is there anything here that is not covered by the runtime metrics package?

I think a bunch of the metrics in https://go.dev/cl/38180 are not covered by the runtime/metrics package. I've had it on my TODO list for a while but it's never quite made it to the top. Clearly not for this release, but I continue to hope.

In terms of the proposal process, I don't think this needs to be on hold anymore. Adding new metrics is a fair bit more lightweight than it used to be, so even if we don't see an obvious use-case right now, the bar is low enough that I'm comfortable with just adding the remaining metrics.

In terms of the original proposal, I think all we're missing is counts of goroutines in various states, total count of goroutines created (to create a rate metric), and a thread count. (We already have a histogram metric for time spent in "runnable.")

If someone would like to take a stab at implementing this, please be my guest. Otherwise, I'll get to it next cycle.

If someone would like to take a stab at implementing this, please be my guest. Otherwise, I'll get to it next cycle.

@mknyszek Thanks. Should we keep this issue open and retarget to runtime/metrics? Or should we open a new proposal?

We can keep this issue open and retarget it. I'll update the header and such.

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

Retitled based on #15490 (comment).
This is about per-state goroutine counts, a count of total goroutines created, and total number of OS threads.

Have all concerns about this proposal been addressed?

Yeah, I believe all concerns are addressed.

Based on the discussion above, this proposal seems like a likely accept.
— rsc for the proposal review group

No change in consensus, so accepted. 🎉
This issue now tracks the work of implementing the proposal.
— rsc for the proposal review group

As for what these metrics should be named, perhaps:

/sched/threads:threads
/sched/goroutines-created:goroutines (cumulative)
/sched/goroutines/waiting:goroutines
/sched/goroutines/runnable:goroutines
/sched/goroutines/running:goroutines
/sched/goroutines/not-in-go:goroutines

The goroutine state metrics come from https://go-review.googlesource.com/c/go/+/38180/9/src/runtime/pstats.go#18. I figure we can reuse most of that implementation.

/sched/goroutines/not-in-go:goroutines is intended to cover syscalls and cgo, I assume? i.e., it is _Gsyscall?

This issue is currently labeled as early-in-cycle for Go 1.22.
That time is now, so a friendly reminder to look at it again.

This issue is currently labeled as early-in-cycle for Go 1.23.
That time is now, so a friendly reminder to look at it again.