Blockers

[kartikcho]

Unknowns/Need info

• What is the "render-idle" ReactMeasureType defined in the scheduler POC code?
• Why does the scheduler prototype not work with custom captured profiles from a demo concurrent mode app?
  I used multiple captured json performance profiles from the above test app with the scheduler and got empty graphs.

Extra info: How was the data recorded for the demo?

• The recent lanes branch displays multiple cooperative chunks of work running at the same time, does it still needs to be worked on? (Can't check without test data).

Needs further investigation

• React timings and stack flame graphs don't align correctly
• Prototype on hover tooltip display is a hit and miss (sometimes works, sometimes doesn't, doesn't display context menu for some user timing marks or "dots").

[bvaughn]

What is the "render-idle" ReactMeasureType defined in the scheduler POC code?

When React finishes "render" work, it could be for a few reasons:

• Idle: Yielding to the browser to do whatever it needs to (e.g. process user input, other non-React JavaScript). We'll resume rendering this work later.
• Interrupted: Higher priority work needs to be worked on, so we are going to throw away the in-progress render.
• Completed: All render work is done and is safe to be committed at some future time (not necessarily immediately).

Why does the profiler not work with custom captured profiles from a demo concurrent mode app?

I don't understand this question. DevTools Profiler works fine at the link you sent.

May be worth pointing out that there is an ongoing Chromium bug that impacts React DevTools (as well as many other extensions) that might be what you're asking about? facebook/react#19002

The recent lanes branch displays user timing marks for multiple things running at the same time, does it still needs to be worked on? (Can't check without test data).

Going to need more info here. Which "user timing marks" are you referring to? and what do you mean by "at the same time"?

[kartikcho]

Sorry I wasn't clear in my post and realized I used incorrect terms to refer to different things. I've edited my original post, hopefully that helps explain my thoughts better @bvaughn.

[bvaughn]

Ah ok. I think you're asking about the fact that the lanes branch supports working on multiple "priorities" at the same time.

Yes, this will likely require a bit of rethinking.

Not sure if you saw my comment over on MLH-Fellowship/react#5 (comment), but I'm going to chat with the team during our sync today (in a couple of hours) and hopefully get back to you soon about this.

[kartikcho]

Not sure if you saw my comment over on MLH-Fellowship/react#5 (comment), but I'm going to chat with the team during our sync today (in a couple of hours) and hopefully get back to you soon about this.

Yes, I did. Thanks!
Could you also let me know how to produce test data for the prototype? I can work on adding an import button till anything is decided.

[bvaughn]

"produce test data" as in...new test data? That will require adding the new user timing marks to React behind a feature flag.

You could produce test data using an older build of React (from my old branch facebook/react#17772) too though if you'd rather not wait. Just be aware that the data may be different than what we're going to end up with given the lanes refactor.

[kartikcho]

Alright, I'll add a dummy import button until user timing marks are added. Thanks.

[bvaughn]

I could probably dig up a JSON file from a few months back if you'd just like some sample data, but really... probably just design the button and get the file import logic working to parse any JSON for now, then hold off until tomorrow when we know a little more about the lanes update my other comment refers to :)