IssueTracker

Hi there.

I was working on the app with coroutines as base for domain layer and started to get strange StackOverflowError exceptions in crash reports from Crashlytics after publishing the app as alpha version. Crashes appear only in release build (with R8 in full mode and "proguard-android-optimize.txt" rules set). But as stacktraces pointed to coroutine classes, I decided to open an issue in kotlinx.coroutines repository first. They advised me to create an issue here.

I created a simple repository as example to show the issue - https://github.com/epetrenko/FlowExample. It's simplified a lot, production app has much more complicated architecture.

In short, there is a view model class which collects flow in init block:

init {
    viewModelScope.launch {
        flow {
            val list = arrayListOf<Int>()
            for (i in 0..100) {
                list.add(Random(100).nextInt())
            }
            emit(list)
        }.flowOn(Dispatchers.Default)
            .distinctUntilChanged()
            .collect { list ->
                Log.e("Collect list", list.toString())
            }
    }
}

flowOn(Dispatchers.Default) and distinctUntilChanged() methods are placed here just to match the behavior of the production app, where crashes basically occurred. Also I emulated release mode by setting the following in build.gradle:

debug {
    debuggable false
    minifyEnabled true
    shrinkResources true
    proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}

And android.enableR8.fullMode=true in gradle.properties.

Actual issue is in that app crashes with these parameters, but everything works fine with another variations. I've got the following results. Crash doesn't appear if:

1. Set debuggable to true
2. Using proguard-android.txt instead of proguard-android-optimize.txt
3. Removing android.enableR8.fullMode=true. Works for both proguard-android.txt and proguard-android-optimize.txt
4. Removing .flowOn(Dispatchers.Default) from chain
5. Using the same dispatchers for .flowOn() and viewModelScope.launch()

Deobfuscated stacktrace (using ReTrace from ProGuard) for example app is also attached.