Using Ktor results in CallNotFoundException due to work on wrong thread

報告在 withContext(Dispatchers.IO) 中重現了 PlacesApi.placeAutocomplete(...).await()，並在堆疊追蹤中指向 GaePendingResult.await。首先重現 Ktor/App Engine 請求，並追蹤協程調度器如何與函式庫的請求處理互動。確認與執行緒相關的失敗，且 repository 中有受支援的修正或明確記錄的相容性指南後，即可視為完成。

I'm using Ktor, which is based on coroutines. This seems to be conflicting with the thread manager that the Google Maps Platform Java library uses. It keeps giving me an Unexpected exception from com.google.apphosting.api.ApiProxy$CallNotFoundException: Can't make API call urlfetch.Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager error.

Environment details

1. Specify the API at the beginning of the title (for example, "Places: ...")
2. OS type and version
3. Library version and other environment information

Places Autocomplete
Kotlin 1.4
0.11.0

Steps to reproduce

1. Make a request to PlacesApi.placeAutocomplete(context, query, null).await()

Code example

fun Application.placesAutocomplete() {
    routing {
        get("/v1/places/autocomplete") {
            val parameters = call.request.queryParameters
            val query: String? = parameters["query"]
            val type: String? = parameters["type"]

            if (query == null) {
                call.respondParameterRequired("query")
                return@get
            }

            if (query.isBlank()) {
                call.respond(AutocompleteResponse(emptyList()))
                return@get
            }

            val PLACES_KEY = System.getenv("PLACES_KEY")

            val placeAutocompleteTypes = try {
                type?.let { PlaceAutocompleteType.valueOf(type) }
            } catch (e: IllegalArgumentException) {
                call.respond(HttpStatusCode.BadRequest, "Invalid place type")
                return@get
            }

            val context = GeoApiContext.Builder(GaeRequestHandler.Builder()).apiKey(PLACES_KEY).build()

            val placeAutocompleteRequest = PlacesApi.placeAutocomplete(context, query, null)
            placeAutocompleteTypes?.let { types ->
                placeAutocompleteRequest.types(types)
            }

            try {
                val placeAutocompleteResponse = withContext(Dispatchers.IO) { placeAutocompleteRequest.await() }
                val places = placeAutocompleteResponse.map {
                    val formatting = it.structuredFormatting
                    Place(
                        placeId = it.placeId, mainText = formatting.mainText
                            ?: "", secondaryText = formatting.secondaryText
                            ?: ""
                    )
                }

                val autocompleteResponse = AutocompleteResponse(places)
                call.respond(autocompleteResponse)
            } catch (e: Exception) {
                call.respond(HttpStatusCode.InternalServerError, e)
            }
        }
    }
}

Stack trace

com.google.maps.errors.UnknownErrorException: Unexpected exception from com.google.apphosting.api.ApiProxy$CallNotFoundException: Can't make API call urlfetch.Fetch in a thread that is neither the original request thread nor a thread created by ThreadManager
	at com.google.maps.internal.GaePendingResult.await(GaePendingResult.java:121)
	at com.google.maps.PendingResultBase.await(PendingResultBase.java:58)
	at appengine.PlacesAutocompleteKt$placesAutocomplete$1$1$placeAutocompleteResponse$1.invokeSuspend(PlacesAutocomplete.kt:74)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
	at kotlinx.coroutines.EventLoopImplBase.processNextEvent(EventLoop.common.kt:272)
	at kotlinx.coroutines.BlockingCoroutine.joinBlocking(Builders.kt:79)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking(Builders.kt:54)
	at kotlinx.coroutines.BuildersKt.runBlocking(Unknown Source)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking$default(Builders.kt:36)
	at kotlinx.coroutines.BuildersKt.runBlocking$default(Unknown Source)
	at appengine.PlacesAutocompleteKt$placesAutocomplete$1$1.invokeSuspend(PlacesAutocomplete.kt:74)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTaskKt.resume(DispatchedTask.kt:175)
	at kotlinx.coroutines.DispatchedTaskKt.resumeUnconfined(DispatchedTask.kt:137)
	at kotlinx.coroutines.DispatchedTaskKt.dispatch(DispatchedTask.kt:108)
	at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:307)
	at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl(CancellableContinuationImpl.kt:317)
	at kotlinx.coroutines.CancellableContinuationImpl.resumeWith(CancellableContinuationImpl.kt:249)
	at retrofit2.KotlinExtensions$awaitResponse$2$2.onResponse(KotlinExtensions.kt:93)
	at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:129)
	at okhttp3.RealCall$AsyncCall.execute(RealCall.java:174)
	at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)