Hi there. I couldn’t get why this code was being run on the main thread (why wouldn’t suspend functi...

# coroutines

[ubu]

Hi there. I couldn’t get why this code was being run on the main thread (why wouldn’t suspend function create its own thread):

override suspend fun createAccount(
        name: String,
        avatarPath: String?
    ) : AccountEntity {

        Timber.d("Thread: ${Thread.currentThread().name}")

        return service.createAccount(name, avatarPath).let { response ->
            AccountEntity(
                id = response.id,
                name = response.name,
                avatar = response.avatar.toEntity()
            )
        }
    }

I launch inside ViewModelScope. Any help will be appreciated!

[diesieben07]

The suspend modifier only means "this function can suspend". It does not say anything about on which thread it will run.

[ubu]

@diesieben07, thanks. I actually run it in the following manner:

abstract class BaseUseCase<out Type, in Params> where Type : Any {

    abstract suspend fun run(params: Params): Either<Throwable, Type>

    open operator fun invoke(
        scope: CoroutineScope,
        params: Params,
        onResult: (Either<Throwable, Type>) -> Unit = {}
    ) {
        val backgroundJob = scope.async { run(params) }
        scope.launch { onResult(backgroundJob.await()) }
    }

    object None
}

invoke() gets ViewModelScope

[diesieben07]

I am unfamiliar with Android, but I don't think ViewModelScope specifies a background thread either.

[louiscad]

Read the docs on d.android.com/kotlin/coroutines and kotl.in/coroutines

[gildor]

viewModelScope always run on Main dispatcher by default

[gildor]

Use withContext(SomeDispatcher) {} to switch thread (you can use Dispatchers.IO)

[gildor]

I recommend you to read official coroutine guide how dispatchers work

[ubu]

thanks a lot