Fibers PoC

[torsteingrindvik]

It's not pretty (the Rust code I mean)- I just wanted to see what it looked like.

EDIT: I whoopsed the location of the join prints, nvm them

One strange thing is that it reports finishing after negative time:

The example follows section "3.10 Fiber" of the Tracy manual. Kinda. Added some subspans just to see things nest well.

All in all I think this is interesting- doing this properly could allow having Rust work sent across threads properly tracked. Not sure how it looks in a real life complex app with lots and lots of spans though.

Opening up in case someone wants to try/discuss. I don't intend to do anything more at the moment.

[nagisa]

Thank you for experimenting with this. Fiber-based visualization is definitely desirable for Rust, especially async and tracing integration. Unfortunately the profiling perf impact simply by enabling fiber feature is so severe that I never really pursued it further. It definitely is not something that we could enable by default, and that alone requires a lot of design work, unfortunately.