StackOverflowError is not reported

[odzhychko]

Description

I created the following example:

package dev.oleks

import com.badoo.reaktive.single.flatMap
import com.badoo.reaktive.single.subscribe
import com.badoo.reaktive.single.toSingle


fun main() {
    var mapSingle = emptyMap<Int, String>().toSingle()
    repeat(5000) { index ->
        mapSingle = mapSingle.flatMap { map ->
            (map + (index to index.toString())).toSingle()
        }
    }

    var result: Result<Map<Int, String>>? = null
    mapSingle.subscribe(onSuccess = {
        result = Result.success(it)
    }, onError = {
        result = Result.failure(it)
    })
    checkNotNull(result) { "Neither onSuccess nor onError was called" }
    println(result!!.getOrThrow().size)
}

Running it with version 2.3.0 results in the following output:

Exception in thread "main" java.lang.IllegalStateException: Neither onSuccess nor onError was called
        at dev.oleks.MainKt.main(Main.kt:22)
        at dev.oleks.MainKt.main(Main.kt)

Note, that neither the onError was called nor the "onError callback failed" message was printed.

When setting a breakpoint in error handling code, the following original stack trace can be recovered:

java.lang.StackOverflowError
	at com.badoo.reaktive.utils.HandleSourceErrorKt.handleReaktiveError(HandleSourceError.kt:9)
	at com.badoo.reaktive.single.FlatMapKt$flatMap$1$1.onSuccess(FlatMap.kt:52)
	at com.badoo.reaktive.single.SingleByEmitterKt$onSubscribeSingle$1.onSuccess(SingleByEmitter.kt:27)
	at com.badoo.reaktive.single.FlatMapKt$flatMap$1$1$onSuccess$1$1.onSuccess(FlatMap.kt)
	at com.badoo.reaktive.single.VariousKt$singleOf$$inlined$singleUnsafe$1.subscribe(Various.kt:21)
	at com.badoo.reaktive.single.VariousKt$singleOf$$inlined$singleUnsafe$1.subscribe(Various.kt:13)
	at com.badoo.reaktive.single.FlatMapKt$flatMap$1$1.onSuccess(FlatMap.kt:24)
	at com.badoo.reaktive.single.SingleByEmitterKt$onSubscribeSingle$1.onSuccess(SingleByEmitter.kt:27)
	at com.badoo.reaktive.single.FlatMapKt$flatMap$1$1$onSuccess$1$1.onSuccess(FlatMap.kt)
	at com.badoo.reaktive.single.VariousKt$singleOf$$inlined$singleUnsafe$1.subscribe(Various.kt:21)
	at com.badoo.reaktive.single.VariousKt$singleOf$$inlined$singleUnsafe$1.subscribe(Various.kt:13)
	at com.badoo.reaktive.single.FlatMapKt$flatMap$1$1.onSuccess(FlatMap.kt:24)
        ....

Additional information

The issue seems similar to ReactiveX/RxJava#748.

Other JVM implementations of Reactive Extensions rethrow VirtualMachineError (e.g, StackOverflowError), ThreadDeath and LinkageError¹² because they cannot always be recovered from.

Footnotes

1. https://github.com/reactor/reactor-core/blob/7259f57d52aafa7f23d6863962ef790ac18f7095/reactor-core/src/main/java/reactor/core/Exceptions.java#L453 ↩

2. https://github.com/ReactiveX/RxJava/blob/5c8ddcba3f40f37a24808c17d2cb26d08c370db7/src/main/java/io/reactivex/rxjava3/exceptions/Exceptions.java#L66 ↩

[arkivanov]

Thanks, I will try fixing it.