Ability to introspect the event loop

[strugee]

(Leaving out the issue template as this is a feature request - hopefully this is okay; CONTRIBUTING.md doesn't really specify.)

I'm the maintainer for pump.io, a server written in Node.js. I'm working on a feature to implement zero-downtime restarts which involves gracefully shutting down and then respawning cluster processes. Basically the way this works is that the master process uses worker.send to signal the worker to call server.close() on the HTTP server(s), and then everything else in the process is shut down after that completes.

However, there's still stuff keeping the process open - AFAICT some listener must still be on the event loop. It would be really awesome if I had a way to say, "just dump stack traces of everything you're watching for on the event loop" so I could track down where these listeners are being registered in the first place. (Or maybe I'm going about this all wrong? If so feel free to say so.)

[strugee]

For anyone stumbling on this issue in the future, https://www.npmjs.com/package/wtfnode is apparently a thing. It is not a Good Thing:tm:, however, because private methods.

[Trott]

Hi @strugee!

Check out #1128 for a previous discussion.

I think this is now possible to accomplish with the experimental async-hooks.

[bnoordhuis]

Answered, closing.