test: implement setproctitle for windows

[refack]

Fixes: #14039

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• commit message follows commit guidelines

Affected core subsystem(s)

test,process,windows

[addaleax]

Why this change? (to clarify: I’m sure there’s a reason, I just don’t see it?)

[refack]

I was checking what is actually the limit, and it turns out to be 4 chars, and it fails on my machine (when pid > 10000), so I picked a fairly random seed, and truncated to 4.

[addaleax]

Can you use a constant value then? I know this wasn’t the case before, but it’s not really a good idea to use random values in tests, where reproducibility matters (alternative: print the title to stderr, that should work as well)

[refack]

Ohhh. that's a good idea!
...
But it only give us node's "internal" view, while ps gives us how the external system sees the title
...
The issue with a constant value is that zombies will give us a false positive. We need a secret that only know to the testing process

[addaleax]

Oh, right. Yeah, in that case, print it out to stderr.

[refack]

I could add some more comments, this is fairly black magic stuff...

[vsemozhetbyt]

FWIW, the reason to be careful with constants (or something that can be equal by a chance in different runs) here: #12792

[refack]

I'm totally not in love with the new code, if anybody has any idea how to improve it, please 🙏
/cc @nodejs/platform-windows @nodejs/testing @richardlau

[richardlau]

Could do with a short comment here stating that changing the title on Windows changes the title of the Window, which may not be the node process. This add s bit of context as to why the test is different on Windows.

[richardlau]

I think this is subject to race condition, where the PowerShell script may run before the spawned child process changes the title? Maybe we can use fork() instead of spawn() and use the IPC channel for sequencing? Would also have the benefit of not having to kill the child.

[refack]

I'll research that, also I think there is a guarantee that something (not sure what) has to finish before spawn returns.
Also AFAIK it's possible to establish an IPC via spawn

[refack]

P.S. I have seen inconsistant results but I attributed them to the child exiting too soon 🤔

[richardlau]

Again, with IPC we could get the child to wait around instead of arbitrary timeout.

[refack]

Can't use IPC because the script is run not in the child but in a grandchild created with START...

[BridgeAR]

Hm, is there any solution to this? Because without this solved it seems like there can not be any progress.

[BridgeAR]

@refack this needs a rebase

[BridgeAR]

@nodejs/testing PTAL

[BridgeAR]

@nodejs/platform-windows PTAL

[BridgeAR]

Ping @nodejs/testing @nodejs/platform-windows again. PTAL

[richardlau]

I'm still concerned that there's a race condition in the test that would introduce a new flake.

[BridgeAR]

Closing due to no further progress. If someone thinks this should be reopened, please do so.