Delete unstable scheduler/tracing entry point

[bvaughn]

[eps1lon]

For what it's worth:
I've used scheduler/tracing with React.Profiler to profile our components by re-using tests. Didn't have time to fully explore it (using timings, aggregating etc) but it already helped identify "over-committing" i.e. interactions that we'd like to handle in a single commit.

Removal of scheduler/tracing would mean we wouldn't be able to link back to the programmatic interaction in a test or rather just to the test but not the specific line). I think we could still disagreggate all render results into interactions for our specific usage.

Initial implementation: https://github.com/mui-org/material-ui/pull/24289/files#diff-11c29f77f44b9b70ef2fb4c1f11523bd53bf3bed1d82dca2efcaabf945667076
Example profiling session (note the links to the sourcecode which implemented via scheduler/tracing): https://mui-dashboard.netlify.app/test-profile/240420/details/%3CAutocomplete%20%2F%3E%20click%20input%20should%20maintain%20list%20box%20open%20clicking%20on%20input%20when%20it%20is%20not%20empty (overview of all tests: https://mui-dashboard.netlify.app/test-profile/240420)

[bvaughn]

I hear you. Unfortunately it doesn't work well with larger modern React apps with batched updates and lots of Suspense usage. When React batches updates together, their interactions get entangled and then the data because noisy. Cascading updates also carry along all of the entangled updates.

There's a need for a good API here, but scheduler/tracing isn't it. First step is to remove it. Later step will be to design a better replacement.

[eps1lon]

All good. Just wanted to share a concrete use case since you did ask a while back on twitter I think and I didn't have it ready at the time.

Making it a noop silently would have been better for me. Now I'm reminded of how cool this seemed and now I'm sad it's gone 😄

[bvaughn]

Sorry 😁

[samcooke98]

Sorry for the ping, @bvaughn, what do you think of removing the interactions tab from the react-devtools? I'd be willing to submit a PR if you're open for it.

I was just about to start using unstable_trace to help diagnose some issues, and nearly started using it before realising it was removed

[bvaughn]

@samcooke98 That tab was already removed (as part of #20037).

[samcooke98]

Oh my bad, it seems I was running an old development version 🤦 - sorry!

[bvaughn]

Haha no problem! :D