src: use node- prefix on thread names

[sxa]

This was spotted while doing some other work - the changes made in #56416 (and there were further updates in #59601) mean that when looking at the top output the node process just show as a rather vague MainThread. To the average user this is likely to be a little confusing as to which process it is and potentially lead people to have concerns about a seemingly rogue named process on their machines (Pressing c within top clarifies it, but I'm looking at the general simple use case).

As mentioned in the screenshots included in the original PR, htop does not show the main thread name by default so this may have not been spotted in the original testing.

This PR adjusts the threadnames to have a node- prefix so that the output from top shows something more meaningful by default - specifically node-MainThread.

Other options considered:

1. I initially looked at calling the main thread nodejs-MainThread but by default the text in the top output got truncated at nodejs-MainThre which isn't ideal. I also considered node (main) as an alternative option.
2. We could put the name of the main thread back to the default and not override it. This would likely provide adequate differentiation from all the others which we are naming for the purposes of debugging.
3. If we wanted to avoid lengthening all of the thread names (others can decide if that's a concern) we could change the main thread as per this PR and leave the others, since it will be more obvious from any analysis that they are connected to the main thread
4. We could leave it as is and just say the that the top output isn't sensible, but since it's probably the most widely used tool for this sort of thing I think it's best to improve how we look there.

I've included a screenshot showing what each option looks like in the top output shown below. Process 930775 is the current main code, 583671 is with this PR, 467427 and 587572 are the other ones from option 1 above.

[nodejs-github-bot]

Review requested:

• @nodejs/inspector
• @nodejs/startup

[github-actions]

The notable-change PRs with changes that should be highlighted in changelogs. label has been added by @sxa.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.51%. Comparing base (bcdf2e0) to head (c0fe99d).
⚠️ Report is 34 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61307      +/-   ##
==========================================
- Coverage   88.53%   88.51%   -0.02%     
==========================================
  Files         704      704              
  Lines      208759   208739      -20     
  Branches    40281    40268      -13     
==========================================
- Hits       184816   184762      -54     
- Misses      15947    15972      +25     
- Partials     7996     8005       +9     

Files with missing lines	Coverage Δ
src/node.cc	75.96% <100.00%> (ø)
src/node_platform.cc	76.24% <100.00%> (ø)

... and 40 files with indirect coverage changes

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[mcollina]

lgtm

[richardlau]

cc @nodejs/diagnostics

@sxa You'll need to fix the expected thread name in the failing test.

[sxa]

@sxa You'll need to fix the expected thread name in the failing test.

Argh! Not sure why that didn't show up in my testing. I've got two options for the WorkerThread one:

1. Don't rename it and just revert that part of the test
2. Rename it (although when I tried it the test got a truncated name) so I think for now my preference is to leave it as WorkerThread unless anyone feels strongly that it needs updating with all of the others.

=== release test ===                                                          
Path: addons/uv-thread-name/test
node:internal/event_target:1120
  process.nextTick(() => { throw err; });
                           ^

AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
+ actual - expected

+ 'node-WorkerThre'
- 'node-WorkerThread'
                  ^

[sxa]

This may be a general issue of truncation to 15 characters on Linux because that's what it's limited to (16 including the null terminator:

Thoughts? Re-requesting reviews from those w ho have already approved - should I just revert this to only change the MainThread for now to resolve the original problem I saw to avoid truncation on Linux?

[Qard]

Is there any specific reason to keep the same structure for the rest of the names? If we're going to rename might as well rename fully to fit within those constraints.

[sxa]

Is there any specific reason to keep the same structure for the rest of the names? If we're going to rename might as well rename fully to fit within those constraints.

Not critical, hence why I suspect that a revert of all but the MainThread would be ok. A couple of points:

• The names are visible in top -H which shows the thread names by default but that's probably not a normal use case for non-expert users.
• The DelayedTaskSchedulerWorker and TraceEventWorker will already be getting truncated on Linux even without this PR as they exceed 15 characters (you can see the former getting chopped in the screenshot below)

[sxa]

Latest commit reverts all but node-MainThread and node-V8Worker but I'm open to other options (I could have reverted node-V8Worker too but I personally think that's worth keeping)

[sxa]

CI: https://ci.nodejs.org/job/node-test-pull-request/70740/

Resume passed in 60555 with flakes only on AIX so this is good.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/70788/

[sxa]

Landed in daeafc0