Android: After the app reloads, we're stuck with a dead thread because of SingleThreadAsserter

Environment

Environment: OS: macOS Sierra 10.12.6 Node: 8.4.0 Yarn: 1.5.1 npm: 5.3.0 Watchman: 4.7.0 Xcode: Xcode 9.2 Build version 9C40b Android Studio: 3.0 AI-171.4443003

Packages: (wanted => installed) react: 16.2.0 => 16.2.0 react-native: 0.53.0 => 0.53.0

Expected Behavior

I would expect the SingleThreadAsserter to clear the mThread value after the app reloads, so that a new thread can be used on every assertion from that point in.

https://github.com/facebook/react-native/blob/26684cf3adf4094eb6c405d345a75bf8c7c0bf88/ReactAndroid/src/main/java/com/facebook/react/common/SingleThreadAsserter.java#L23

Actual Behavior

Instead, the SingleThreadAsserter locks to the thread it was created with, so when the app reloads, and that thread dies we’re stuck with a dead thread, which causes all subsequent assertions to fail. Almost every uiManager method requires that assertion, so that’s a big issue.

Steps to Reproduce

Here’s a repo that suffers from that issue. https://github.com/SudoPlz/react-native-synchronous-list

1. Download
2. cd RNExample
3. yarn install
4. Run the android project.

All works well until you reload. After the reload we get:

FATAL EXCEPTION: main
 Process: com.rnexample, PID: 8519
 java.lang.AssertionError
     at com.facebook.infer.annotation.Assertions.assertCondition(Assertions.java:66)
     at com.facebook.react.common.SingleThreadAsserter.assertNow(SingleThreadAsserter.java:27)
     at com.facebook.react.uimanager.ShadowNodeRegistry.getNode(ShadowNodeRegistry.java:67)
     at com.facebook.react.uimanager.UIImplementation.createView(UIImplementation.java:278)
     at com.facebook.react.uimanager.UIManagerModule.createView(UIManagerModule.java:364)
     at com.sudoplz.rnsynchronouslistmanager.Views.SyncRootView$3.run(SyncRootView.java:172)
     at android.os.Handler.handleCallback(Handler.java:751)
     at android.os.Handler.dispatchMessage(Handler.java:95)
     at android.os.Looper.loop(Looper.java:154)
     at android.app.ActivityThread.main(ActivityThread.java:6119)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

[SudoPlz]

Got it, always requesting the current react application context fixed the issue, thank you so much @janicduplessis !

[janicduplessis]

I had a quick look at the code and is it possible that you are holding on to an old instance of ReactApplicationContext? I think you should use ReactInstanceManager##getCurrentReactContext to make sure you have the proper one like the code in ReactRootView does.

You could override https://github.com/facebook/react-native/blob/2b6599e9c8b393bb20bf04e206d8982f587e75dd/ReactAndroid/src/main/java/com/facebook/react/ReactRootView.java#L356 to get the ReactInstanceManager since it is private in ReactRootView sadly.