process: add libuvHandlesCount()

[XadillaX]

This method is to count libuv handles of current tick.

Checklist

• make -j4 test (UNIX) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[nodejs-github-bot]

Lite-CI: https://ci.nodejs.org/job/node-test-pull-request-lite-pipeline/3205

[joyeecheung]

If we are going to add a method that returns the handles, I think a better place would be perf_hooks since that's where we have been adding similar statistics.

[joyeecheung]

We should not hard code this in JS land, this can be attached in the binding - e.g. see require('os').constants

[XadillaX]

@joyeecheung it's not returning the handles but handles count.

[mscdex]

What's the use case for this? If it's to find what's keeping a process alive, don't we have user-friendly ways of determining that nowadays, such as with the built-in reporting functionality or something similar?

[sam-github]

Wouldn't it be better to return info about the handles in an array, and if anyone wants a count, they can get the array length, or count handles of a particular type or status in the array?

[addaleax]

Fwiw, @sam-github’s suggestion sounds very close to process._getActiveHandles(). We’ve had some discussion around making that an “official” API for a while, e.g. in #21453. The major differences would be that:

• We do not track all our handles in that currently, only the ones that correspond to JS wrappers. I’d like to change that, but it would require some low-level refactoring.
• We do not track handles that are not created by Node.js, e.g. by addons or embedders. I think that’s okay.

[richardlau]

Use case(s) would be helpful. You can get the handles via report:

const handles = JSON.parse(process.report.getReport()).libuv
const count = Object.keys(handles).length - 1 // -1 accounts for synthetic `loop` type

[Fishrock123]

I think my proposed idea if "getActiveResources" covers this better. See #21453

(I would like to get back to that, but not quite sure when...)

[joyeecheung]

it's not returning the handles but handles count.

@XadillaX um, I am confused, does that have anything to do with either of my previous comments?

EDIT: oh, right, I didn't include the word count in my first comment, sorry. But the comments still apply whether it's returning counts or not.

[XadillaX]

What's the use case for this? If it's to find what's keeping a process alive, don't we have user-friendly ways of determining that nowadays, such as with the built-in reporting functionality or something similar?

We may use the count to draw some health chart.

[mscdex]

I don't understand how a handle count has any bearing on process "health"? If anything, process "health" would be more a measure of things like event loop pauses, memory/cpu usage, etc.

But anyway, it sounds like this would be better solved by the built-in process reporting feature instead.

[XadillaX]

So shall I continue working for this PR? or any suggestions?

[szmarczak]

@XadillaX I'm looking forward to this PR. @Fishrock123 probably had forgotten about his PR.

[Fishrock123]

I have not forgotten about mine, but some things have changed and I don't have any real reason to see it through.

I still think this not the correct approach.

[szmarczak]

I have not forgotten about mine, but some things have changed and I don't have any real reason to see it through.

If only I had known that before :P Okay, I'll work on yours then. It doesn't seem like there's much work to do.

[jasnell]

This unfortunately has stalled out and has not seen any further activity. Closing but it can be reopened if it is picked back up again and rebased