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Ktor-client inside CoroutineWorker.execute - Uncaught Kotlin exception: kotlin.native.IncorrectDereferenceException: Trying to access top level value not marked as @ThreadLocal or @SharedImmutable from non-main thread

See original GitHub issue

I just watched the talk that @benasher44 gave at droidCon NYC about Concurrency in Kotlin/Native and decided to try this CoroutineWorker library.
So what I am trying to do is consuming some backend REST API using Ktor inside CoroutineWorker.execute. Basically, I am still not really sure if I am doing this correct but here is the code:

So I have a NetworkProvider class:

internal class NetworkProvider<T : Endpoint>(private val engine: HttpClientEngine) {

    private val client: HttpClient by lazy {
        HttpClient(engine) {
            install(JsonFeature) {
                serializer = KotlinxSerializer()

    internal suspend fun <R> request(endpoint: T, strategy: DeserializationStrategy<R>): R {

        val response: String = client.request {
            method = endpoint.method
            url.apply {
                protocol = URLProtocol.HTTPS
                host = endpoint.baseUrl

                val query = endpoint.parameters
                    .map { "${it.key}=${it.value}" }

                encodedPath = if (query.isNotEmpty()) {
                } else {

        return Json.nonstrict.parse(strategy, response)


And then I use this NetworkProvider inside my Repository class like this:

internal class MovieRepositoryImpl(
    private val provider: NetworkProvider<MovieEndpoint>
) : MovieRepository {

    override fun getMovieList(
        year: Int,
        page: Int,
        sort: String,
        completion: (Result<MovieListEntity>) -> Unit
    ) {

        CoroutineWorker.execute {

            val result = try {
                val response = provider.request(
                    endpoint = MovieListEndpoint(year, page, sort),
                    strategy = MovieListEntity.serializer()
            } catch (error: Throwable) {

            CoroutineWorker.withContext(MainDispatcher) {


But it’s end up gave me this error messages:

Uncaught Kotlin exception: kotlin.native.IncorrectDereferenceException: Trying to access top level value not marked as @ThreadLocal or @SharedImmutable from non-main thread
        at 0   MovieCore                           0x0000000109964fe7 kfun:kotlin.Throwable.<init>(kotlin.String?)kotlin.Throwable + 87
        at 1   MovieCore                           0x000000010995e355 kfun:kotlin.Exception.<init>(kotlin.String?)kotlin.Exception + 85
        at 2   MovieCore                           0x000000010995df15 kfun:kotlin.RuntimeException.<init>(kotlin.String?)kotlin.RuntimeException + 85
        at 3   MovieCore                           0x0000000109990c95 kfun:kotlin.native.IncorrectDereferenceException.<init>(kotlin.String)kotlin.native.IncorrectDereferenceException + 85
        at 4   MovieCore                           0x00000001099add29 ThrowIncorrectDereferenceException + 137
        at 5   MovieCore                           0x0000000109cd3799 CheckIsMainThread + 25
        at 6   MovieCore                           0x0000000109c5a893 kfun:utils.<get-MainDispatcher>$core()kotlinx.coroutines.CoroutineDispatcher + 35
        at 7   MovieCore                           0x0000000109c3f7e4 kfun:repository.MovieRepositoryImpl.$getMovieList$lambda-1COROUTINE$1.invokeSuspend#internal + 1892
        at 8   MovieCore                           0x0000000109c40020 kfun:repository.MovieRepositoryImpl.$getMovieList$lambda-1COROUTINE$1.invoke#internal + 256
        at 9   MovieCore                           0x0000000109b069f3 kfun:kotlinx.coroutines.intrinsics.startUndispatchedOrReturn$kotlinx-coroutines-core@kotlinx.coroutines.internal.ScopeCoroutine<#GENERIC>.(#GENERIC;kotlin.coroutines.SuspendFunction1<#GENERIC,#GENERIC>)Generic + 899
        at 10  MovieCore                           0x0000000109ab11bd kfun:kotlinx.coroutines.coroutineScope(kotlin.coroutines.SuspendFunction1<kotlinx.coroutines.CoroutineScope,#GENERIC>)Generic + 429
        at 11  MovieCore                           0x0000000109c37f70 kfun:com.autodesk.coroutineworker.CoroutineWorker.Companion.WorkItem.$<init>$lambda-1COROUTINE$11.invokeSuspend#internal + 1520
        at 12  MovieCore                           0x0000000109c386a0 kfun:com.autodesk.coroutineworker.CoroutineWorker.Companion.WorkItem.$<init>$lambda-1COROUTINE$11.invoke#internal + 256
        at 13  MovieCore                           0x0000000109c33226 kfun:com.autodesk.coroutineworker.BackgroundCoroutineWorkQueueExecutor.$processWorkItems$lambda-0COROUTINE$7.invokeSuspend#internal + 726
        at 14  MovieCore                           0x0000000109986618 kfun:kotlin.coroutines.native.internal.BaseContinuationImpl.resumeWith(kotlin.Result<kotlin.Any?>) + 712
        at 15  MovieCore                           0x0000000109afb06c + 2732
        at 16  MovieCore                           0x0000000109ab606d kfun:kotlinx.coroutines.EventLoopImplBase.processNextEvent()ValueType + 813
        at 17  MovieCore                           0x0000000109b097c6 kfun:kotlinx.coroutines.BlockingCoroutine.joinBlocking#internal + 1958
        at 18  MovieCore                           0x0000000109b0886e kfun:kotlinx.coroutines.runBlocking(kotlin.coroutines.CoroutineContext;kotlin.coroutines.SuspendFunction1<kotlinx.coroutines.CoroutineScope,#GENERIC>)Generic + 1246
        at 19  MovieCore                           0x0000000109b08de4 kfun:kotlinx.coroutines.runBlocking$default(kotlin.coroutines.CoroutineContext?;kotlin.coroutines.SuspendFunction1<kotlinx.coroutines.CoroutineScope,#GENERIC>;kotlin.Int)Generic + 372
        at 20  MovieCore                           0x0000000109c32da9 kfun:com.autodesk.coroutineworker.BackgroundCoroutineWorkQueueExecutor.enqueueWork$<anonymous>_3#internal + 217
        at 21  MovieCore                           0x0000000109c340fb kfun:com.autodesk.coroutineworker.BackgroundCoroutineWorkQueueExecutor.$enqueueWork$<anonymous>_3$FUNCTION_REFERENCE$7.invoke#internal + 59
        at 22  MovieCore                           0x0000000109c3415b kfun:com.autodesk.coroutineworker.BackgroundCoroutineWorkQueueExecutor.$enqueueWork$<anonymous>_3$FUNCTION_REFERENCE$7.$<bridge-UNN>invoke()#internal + 59
        at 23  MovieCore                           0x0000000109c3cca4 kfun:com.autodesk.coroutineworker.WorkerPool.performWork$lambda-1#internal + 308
        at 24  MovieCore                           0x0000000109c3d0df kfun:com.autodesk.coroutineworker.WorkerPool.$performWork$lambda-1$FUNCTION_REFERENCE$17.invoke#internal + 63
        at 25  MovieCore                           0x0000000109c3d13b kfun:com.autodesk.coroutineworker.WorkerPool.$performWork$lambda-1$FUNCTION_REFERENCE$17.$<bridge-UNN>invoke()#internal + 59
        at 26  MovieCore                           0x00000001099927c1 WorkerLaunchpad + 177
        at 27  MovieCore                           0x0000000109cd8069 _ZN6Worker19processQueueElementEb + 2569
        at 28  MovieCore                           0x0000000109cd8616 _ZN12_GLOBAL__N_113workerRoutineEPv + 54
        at 29  libsystem_pthread.dylib             0x00007fff51c04d36 _pthread_start + 125

Anyone know how to work around this error message?

Issue Analytics

  • State:closed
  • Created 4 years ago
  • Comments:14

github_iconTop GitHub Comments

benasher44commented, Dec 17, 2019

Since there’s no follow up to do with CoroutineWorker, I’m going to close this. Hopefully this helped understand a bit more what’s going on, and further discussion / resolution should probably be redirect to the ktor and Kotlin-native channels in Kotlin slack.

Thanks for using CoroutineWorker! If you disagree with my assessment, feel free to reopen

benasher44commented, Dec 17, 2019

No problem sounds good! Best of luck 😃

Read more comments on GitHub >

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