FreezingException not caught when switching context on native

[erikdewit87]

Given: Object with state marked with ensureNeverFrozen() to detect accidental freezes.
When: withContext(IO) accidentially freezes this
Then: Expect FreezingException to be thrown and caught when switching context
Bug: FreezingException is thrown but not properly caught

gradle: gradle-5.6.2
kotlin = 1.3.72
coroutines = 1.3.5-native-mt
iOS simulator: iPhone 11 pro max running iOS 13.1

Slack discussion:
https://kotlinlang.slack.com/archives/C3SGXARS6/p1590498022256500

Example:

interface TestView {
    fun setContent(content: List<String>)
}

class TestInteractor {
    suspend fun fetch(): List<Int> {
        // simulate network / db interaction
        delay(1000L)
        return (0..100).toList()
    }
}

class TestPresenter(
    val view: TestView,
    val interactor: TestInteractor
) : CoroutineScope {

    val cache = mutableListOf<String>()
    val job = SupervisorJob()
    val exceptionHandler = CoroutineExceptionHandler { _, throwable ->
        println("Caught with CoroutineExceptionHandler:")
        throwable.printStackTrace()
    }

    @InternalCoroutinesApi
    override val coroutineContext: CoroutineContext
        get() = Dispatchers.Main + job + exceptionHandler

    init {
        ensureNeverFrozen()
    }

    fun load() {
        launch {
            println("Start fetching")
            val contentFromNetwork = withContext(Dispatchers.Default) {
                interactor.fetch() // freeze this on purpose to trigger FreezeException
            }

            println(
                "this.isFrozen:${this@TestPresenter.isFrozen} " +
                "interactor.isFrozen:${interactor2.isFrozen} " +
                "cache.isFrozen:${cache.isFrozen}"
            )

            println("Processing")
            val content = contentFromNetwork.map { it.toString() }

            println("Updating local cache")
            cache.addAll(content)

            println("Updating view")
            view.setContent(cache.toList())
        }
    }
}

Output:

Start fetching

While fetching it fails silently. exceptionHandler does not report any exception making it hard to determine what goes wrong.

Wrapping withContext inside try/catch shows a FreezingException is thrown:

val contentFromNetwork = try {
    withContext(Dispatchers.Default) {
        interactor.fetch() // freeze this on purpose to trigger FreezeException
    }
} catch (throwable: Throwable) {
    println("Caught with try/catch:")
    throwable.printStackTrace()
    emptyList()
}

Output:

Start fetching
Start fetching
Caught with try/catch:
kotlin.native.concurrent.FreezingException: freezing of kotlinx.coroutines.$startCoroutine$lambda-0$FUNCTION_REFERENCE$30@2ebba58 has failed, first blocker is com.theothersonline.onecrowd.common.presentation.content.TestPresenter@35c3988
        at 0   onecrowd                            0x00000001074244e7 kfun:kotlin.Throwable.<init>(kotlin.String?)kotlin.Throwable + 87
        at 1   onecrowd                            0x00000001074172b5 kfun:kotlin.Exception.<init>(kotlin.String?)kotlin.Exception + 85
        at 2   onecrowd                            0x00000001074174d5 kfun:kotlin.RuntimeException.<init>(kotlin.String?)kotlin.RuntimeException + 85
        at 3   onecrowd                            0x000000010746bfa1 kfun:kotlin.native.concurrent.FreezingException.<init>(kotlin.Any;kotlin.Any)kotlin.native.concurrent.FreezingException + 641
        at 4   onecrowd                            0x000000010746eefe ThrowFreezingException + 222
        at 5   onecrowd                            0x000000010784c002 FreezeSubgraph + 2642
        at 6   onecrowd                            0x000000010788021b Kotlin_Worker_freezeInternal + 27
        at 7   onecrowd                            0x000000010746c0bb kfun:kotlin.native.concurrent.freeze@T.(){0<kotlin.Any?>}Generic + 59
        at 8   onecrowd                            0x0000000107c4c748 kfun:kotlinx.coroutines.execute$kotlinx-coroutines-core@kotlin.native.concurrent.Worker.(kotlin.Function0<kotlin.Unit>) + 152
        at 9   onecrowd                            0x0000000107c4cae2 kfun:kotlinx.coroutines.WorkerThread.execute(kotlin.Function0<kotlin.Unit>) + 98
        at 10  onecrowd                            0x0000000107c44903 kfun:kotlinx.coroutines.startCoroutine$kotlinx-coroutines-core(kotlinx.coroutines.CoroutineStart;kotlinx.coroutines.AbstractCoroutine<>T>;R;kotlin.coroutines.SuspendFunction1<R,T>){0<kotlin.Any?>;1<kotlin.Any?>}Generic + 1411
        at 11  onecrowd                            0x0000000107aa6be0 kfun:kotlinx.coroutines.withContext(kotlin.coroutines.CoroutineContext;kotlin.coroutines.SuspendFunction1<kotlinx.coroutines.CoroutineScope,T>){0<>kotlin.Any?>}Generic + 1328
        at 12  onecrowd                            0x00000001070f8a03 kfun:com.theothersonline.onecrowd.common.presentation.content.TestPresenter.$loadContent$lambda-1COROUTINE$23.invokeSuspend#internal + 2883
        at 13  onecrowd                            0x0000000107450818 kfun:kotlin.coroutines.native.internal.BaseContinuationImpl.resumeWith(kotlin.Result<kotlin.Any?>) + 712
        at 14  onecrowd                            0x0000000107c080c3 kfun:kotlinx.coroutines.DispatchedTask.run() + 2627
        at 15  onecrowd                            0x0000000107c5a385 kfun:kotlinx.coroutines.DarwinMainDispatcher.dispatch$lambda-0#internal + 85
        at 16  onecrowd                            0x0000000107c5a6fb kfun:kotlinx.coroutines.DarwinMainDispatcher.$dispatch$lambda-0$FUNCTION_REFERENCE$40.invoke#internal + 59
        at 17  onecrowd                            0x0000000107c5a75b kfun:kotlinx.coroutines.DarwinMainDispatcher.$dispatch$lambda-0$FUNCTION_REFERENCE$40.$<bridge-UNN>invoke()#internal + 59
        at 18  onecrowd                            0x0000000107c5b814 _6b6f746c696e782d636f726f7574696e65732d636f7265_knbridge8 + 180
        at 19  libdispatch.dylib                   0x00000001096eedf8 _dispatch_call_block_and_release + 12
        at 20  libdispatch.dylib                   0x00000001096efd6c _dispatch_client_callout + 8
        at 21  libdispatch.dylib                   0x00000001096fde24 _dispatch_main_queue_callback_4CF + 1500
        at 22  CoreFoundation                      0x00007fff23b0ce49 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
        at 23  CoreFoundation                      0x00007fff23b07aa9 __CFRunLoopRun + 2329
        at 24  CoreFoundation                      0x00007fff23b06e66 CFRunLoopRunSpecific + 438
        at 25  GraphicsServices                    0x00007fff38346bb0 GSEventRunModal + 65
        at 26  UIKitCore                           0x00007fff47578dd0 UIApplicationMain + 1621
        at 27  onecrowd                            0x0000000107096d1b main + 75 (/Users/<me>/Git/onecrowd/onecrowd-app/ios/onecrowd/onecrowd/AppDelegate/AppDelegate.swift:13:7)
        at 28  libdyld.dylib                       0x00007fff516ecd29 start + 1
        at 29  ???                                 0x0000000000000001 0x0 + 1
this.isFrozen:false interactor.isFrozen:false cache.isFrozen:false
Processing: 0
Updating local cache
Updating view

Nothing got frozen and an exception is thrown so ensureNeverFrozen() did its job. Notice the exception is caught locally and not by the exceptionHandler. Rethrowing inside the catch still fails silently and does not reach the scope's exceptionHandler

To complete the example here is the output when ensureNeverFrozen() is removed from the initial example. This crashes with an InvalidMutabilityException when updating the

Start fetching
this.isFrozen:true interactor.isFrozen:true cache.isFrozen:true
Processing: 100
Updating local cache
kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen kotlin.collections.ArrayList@9064f8
       at 0   onecrowd                            0x0000000101455517 kfun:kotlin.Throwable.<init>(kotlin.String?)kotlin.Throwable + 87
       at 1   onecrowd                            0x00000001014482e5 kfun:kotlin.Exception.<init>(kotlin.String?)kotlin.Exception + 85
       at 2   onecrowd                            0x0000000101448505 kfun:kotlin.RuntimeException.<init>(kotlin.String?)kotlin.RuntimeException + 85
       at 3   onecrowd                            0x000000010149d095 kfun:kotlin.native.concurrent.InvalidMutabilityException.<init>(kotlin.String)kotlin.native.concurrent.InvalidMutabilityException + 85
       at 4   onecrowd                            0x00000001014a0218 ThrowInvalidMutabilityException + 680
       at 5   onecrowd                            0x0000000101892588 MutationCheck + 104
       at 6   onecrowd                            0x0000000101462630 kfun:kotlin.collections.ArrayList.<set-array>#internal + 96
       at 7   onecrowd                            0x0000000101464b41 kfun:kotlin.collections.ArrayList.ensureCapacity(kotlin.Int) + 593
       at 8   onecrowd                            0x000000010146533f kfun:kotlin.collections.ArrayList.ensureExtraCapacity#internal + 95
       at 9   onecrowd                            0x0000000101465bdb kfun:kotlin.collections.ArrayList.insertAtInternal#internal + 267
       at 10  onecrowd                            0x0000000101466327 kfun:kotlin.collections.ArrayList.addAllInternal#internal + 727
       at 11  onecrowd                            0x0000000101463ee0 kfun:kotlin.collections.ArrayList.addAll(kotlin.collections.Collection<E>)kotlin.Boolean + 192
       at 12  onecrowd                            0x000000010112a405 kfun:com.theothersonline.onecrowd.common.presentation.content.TestPresenter.$loadContent$lambda-1COROUTINE$23.invokeSuspend#internal + 5093
       at 13  onecrowd                            0x0000000101481848 kfun:kotlin.coroutines.native.internal.BaseContinuationImpl.resumeWith(kotlin.Result<kotlin.Any?>) + 712
       at 14  onecrowd                            0x0000000101c390f3 kfun:kotlinx.coroutines.DispatchedTask.run() + 2627
       at 15  onecrowd                            0x0000000101c8b3b5 kfun:kotlinx.coroutines.DarwinMainDispatcher.dispatch$lambda-0#internal + 85
       at 16  onecrowd                            0x0000000101c8b72b kfun:kotlinx.coroutines.DarwinMainDispatcher.$dispatch$lambda-0$FUNCTION_REFERENCE$40.invoke#internal + 59
       at 17  onecrowd                            0x0000000101c8b78b kfun:kotlinx.coroutines.DarwinMainDispatcher.$dispatch$lambda-0$FUNCTION_REFERENCE$40.$<bridge-UNN>invoke()#internal + 59
       at 18  onecrowd                            0x0000000101c8c844 _6b6f746c696e782d636f726f7574696e65732d636f7265_knbridge8 + 180
       at 19  libdispatch.dylib                   0x000000010371fdf8 _dispatch_call_block_and_release + 12
       at 20  libdispatch.dylib                   0x0000000103720d6c _dispatch_client_callout + 8
       at 21  libdispatch.dylib                   0x000000010372ee24 _dispatch_main_queue_callback_4CF + 1500
       at 22  CoreFoundation                      0x00007fff23b0ce49 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
       at 23  CoreFoundation                      0x00007fff23b07aa9 __CFRunLoopRun + 2329
       at 24  CoreFoundation                      0x00007fff23b06e66 CFRunLoopRunSpecific + 438
       at 25  GraphicsServices                    0x00007fff38346bb0 GSEventRunModal + 65
       at 26  UIKitCore                           0x00007fff47578dd0 UIApplicationMain + 1621
       at 27  onecrowd                            0x00000001010c7e8b main + 75 (/Users/erikdewit/Programming/Git/onecrowd/onecrowd-app/ios/onecrowd/onecrowd/AppDelegate/AppDelegate.swift:13:7)
       at 28  libdyld.dylib                       0x00007fff516ecd29 start + 1
       at 29  ???                                 0x0000000000000001 0x0 + 1

[elizarov]

FreezingException should be thrown locally by the design of withContext. The fact that it hangs after that is a bug. I'm fixing it in the upcoming native-mt release. Watch #462 for details.

[qwwdfsad]

Fixed in 1.3.9-native-mt-2