kelset / react-native-new-arch-limits

A quick repo for experimenting with the new arch and its limits

Testing the new architecture's limits

Just a quick test app to validate a few doubts I have been having - basically, I'm starting with a fresh new RN app on latest stable (0.70.4) and throwing a bunch of libs at it to see what works and what doesn't when enabling the new architecture.

Tests matrix

A few things to notice:

• technically, to turn on the new arch you have just one switch, see here. This means both TM and Fabric ON at the same time.
  • there should be ways to only switch ON one or the other.I'll test all the options I can find. (also: from >=71, Android switches, iOS switches )
    • TM on Android: based on this guide, changing this line should do the trick nvm that, it looks like the easiest way of doing that is actually to switch on new arch as expected, via gradle.properties, and manually switch off Fabric and Concurrent. Looks weird, but seems to be working.
    • TM on iOS: based on this guide, adding RCTEnableTurboModule(YES); on this line AND removing this if statement...should do the trick I can't seem to figure out a way to make it happen.
• At the end, when everything else is tested, I'll also try to switch on ConcurrentReact and see what goes kaboom. by default, when turning ON the new arch, concurrent is ON too - read more.
• I picked the libs pretty much on instinct, using directory as a catalogue.
• I'm sticking with Hermes only for now just for time-related reasons

As base test, I'll:

• try to switch on new arch: ✅
• try to switch on TM only: (android)✅ (ios)❌
• try to switch on Fabric only: ❌
  • this is not viable, because Fabric is a TurboModule (basically) so it would go kaboom without TM enabled

Then I'll move to the meat of this experiment: the idea is that I'll add all these libs into the code, and see what happens.

What	which lib	old arch (baseline)	new arch	only TM on
a visual lib with "official support" for new arch	react-native-slider	✅	✅	✅
a visual lib without "official support" for new arch	react-native-webview	✅	❌ (as expected)	✅
a non-visual lib with "official support" for new arch	couldn't find any	🤷‍♂️	🤷‍♂️	🤷‍♂️
a non-visual lib without "official support" for the new arch	react-native-get-random-values	✅	✅	✅
a js-only lib	react-native-bouncy-checkbox	✅	✅	✅
a new-arch only lib	react-native-gradient	❌ (as expected)	✅ (ios) ❌ (android - unexpected)	❌ (as expected)
a new-arch only lib with backward compatibility	need to find one	🤷‍♂️	🤷‍♂️	🤷‍♂️

Specific libs comments or notes

• the fact that FyndX/react-native-gradient fails on pod install when on old arch is expected, it errors because the pod itself depends on React-RCTFabric which is new arch specific
• non-Fabric compatible libraries have this nice fallback of a red box (see screenshot v1 in /docs); it all build fine but simply it won't get loaded
• I think FyndX/react-native-gradient erroring in Android is probably because of the lib itself, not my doing. I already added patch-package to handle the Folly bump (see the patch in /patches)

TODO

• ✅ add "status code" to show which state the thing is in (old/new arch, concurrent on/off) (hats off to @tido64 for this)
• ✅ do basic tests
• ✅ add libraries and sample code one by one, in old arch
• ✅ do the tests (new arch on first)
• ✅ get the app in shape for turning on in new arch proper
• ✅ test the TM only mode in Android
• 🟡 summarize the whole thing into some learnings