RxJava onErrorResumeNext 调用 java.io.InterrupedIOException答案

【问题标题】：RxJava onErrorResumeNext calls java.io.InterrupedIOExceptionRxJava onErrorResumeNext 调用 java.io.InterrupedIOException
【发布时间】：2016-12-02 02:15:00
【问题描述】：

我对 RxJava onErrorResumeNext 运算符有疑问。我想获取位置，然后从服务器获取数据（使用改造）取决于位置，但如果没有位置（错误：序列不包含元素），我想从服务器获取另一个 Observable 的数据（不依赖于位置)。我尝试使用 onErrorResumeNext 运算符，但得到“java.io.InterruptedIOException：线程中断”。

添加 onErrorResumeNext 之前的代码 - 效果很好

LocationService.getUpdatedOrLastKnownLocation(getContext()))
            .flatMap(location -> RestService.getPostsAround(location,0,10)) //offset = 0, limit = 10;
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(subscriber);

带有 onErrorResumeNext 的代码 - 抛出异常

LocationService.getUpdatedOrLastKnownLocation(getContext()))
            .flatMap(location -> RestService.getPostsAround(location,0,10)) //offset = 0, limit = 10;
            .onErrorResumeNext(RestService.getPostsByMapProjection(googleMap.getProjection().getVisibleRegion()))
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(subscriber);

堆栈跟踪：

07-27 22:33:58.384 18632-18632/com.blacksea.plamobi W/System.err: java.io.InterruptedIOException: thread interrupted
07-27 22:33:58.384 18632-18632/com.blacksea.plamobi W/System.err:     at okio.Timeout.throwIfReached(Timeout.java:145)
07-27 22:33:58.385 18632-18632/com.blacksea.plamobi W/System.err:     at okio.Okio$1.write(Okio.java:77)
07-27 22:33:58.385 18632-18632/com.blacksea.plamobi W/System.err:     at okio.AsyncTimeout$1.write(AsyncTimeout.java:155)
07-27 22:33:58.385 18632-18632/com.blacksea.plamobi W/System.err:     at okio.RealBufferedSink.flush(RealBufferedSink.java:221)
07-27 22:33:58.386 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.internal.http.Http1xStream.finishRequest(Http1xStream.java:159)
07-27 22:33:58.386 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.internal.http.HttpEngine.readNetworkResponse(HttpEngine.java:721)
07-27 22:33:58.387 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.internal.http.HttpEngine.access$200(HttpEngine.java:81)
07-27 22:33:58.387 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.internal.http.HttpEngine$NetworkInterceptorChain.proceed(HttpEngine.java:708)
07-27 22:33:58.389 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.internal.http.HttpEngine.readResponse(HttpEngine.java:563)
07-27 22:33:58.389 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.RealCall.getResponse(RealCall.java:241)
07-27 22:33:58.389 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.RealCall$ApplicationInterceptorChain.proceed(RealCall.java:198)
07-27 22:33:58.391 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:160)
07-27 22:33:58.392 18632-18632/com.blacksea.plamobi W/System.err:     at okhttp3.RealCall.execute(RealCall.java:57)
07-27 22:33:58.392 18632-18632/com.blacksea.plamobi W/System.err:     at retrofit2.OkHttpCall.execute(OkHttpCall.java:174)
07-27 22:33:58.392 18632-18632/com.blacksea.plamobi W/System.err:     at retrofit2.adapter.rxjava.RxJavaCallAdapterFactory$RequestArbiter.request(RxJavaCallAdapterFactory.java:171)
07-27 22:33:58.392 18632-18632/com.blacksea.plamobi W/System.err:     at rx.Subscriber.setProducer(Subscriber.java:211)
07-27 22:33:58.393 18632-18632/com.blacksea.plamobi W/System.err:     at rx.Subscriber.setProducer(Subscriber.java:205)
07-27 22:33:58.394 18632-18632/com.blacksea.plamobi W/System.err:     at retrofit2.adapter.rxjava.RxJavaCallAdapterFactory$CallOnSubscribe.call(RxJavaCallAdapterFactory.java:152)
07-27 22:33:58.394 18632-18632/com.blacksea.plamobi W/System.err:     at retrofit2.adapter.rxjava.RxJavaCallAdapterFactory$CallOnSubscribe.call(RxJavaCallAdapterFactory.java:138)
07-27 22:33:58.394 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:50)
07-27 22:33:58.395 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
07-27 22:33:58.395 18632-18632/com.blacksea.plamobi W/System.err:     at rx.Observable.unsafeSubscribe(Observable.java:8460)
07-27 22:33:58.396 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OnSubscribeFlattenIterable.call(OnSubscribeFlattenIterable.java:65)
07-27 22:33:58.396 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OnSubscribeFlattenIterable.call(OnSubscribeFlattenIterable.java:37)
07-27 22:33:58.396 18632-18632/com.blacksea.plamobi W/System.err:     at rx.Observable.unsafeSubscribe(Observable.java:8460)
07-27 22:33:58.398 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:141)
07-27 22:33:58.398 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.reportError(OperatorMerge.java:266)
07-27 22:33:58.398 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.checkTerminate(OperatorMerge.java:810)
07-27 22:33:58.400 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.emitLoop(OperatorMerge.java:571)
07-27 22:33:58.400 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.emit(OperatorMerge.java:560)
07-27 22:33:58.400 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.onError(OperatorMerge.java:276)
07-27 22:33:58.401 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMap$MapSubscriber.onError(OperatorMap.java:85)
07-27 22:33:58.403 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.reportError(OperatorMerge.java:266)
07-27 22:33:58.403 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.checkTerminate(OperatorMerge.java:810)
07-27 22:33:58.403 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.emitLoop(OperatorMerge.java:571)
07-27 22:33:58.404 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$MergeSubscriber.emit(OperatorMerge.java:560)
07-27 22:33:58.404 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorMerge$InnerSubscriber.onError(OperatorMerge.java:844)
07-27 22:33:58.404 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorSubscribeOn$1$1.onError(OperatorSubscribeOn.java:59)
07-27 22:33:58.405 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.checkTerminated(OperatorObserveOn.java:264)
07-27 22:33:58.406 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.call(OperatorObserveOn.java:207)
07-27 22:33:58.406 18632-18632/com.blacksea.plamobi W/System.err:     at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55)
07-27 22:33:58.406 18632-18632/com.blacksea.plamobi W/System.err:     at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:423)
07-27 22:33:58.406 18632-18632/com.blacksea.plamobi W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
07-27 22:33:58.407 18632-18632/com.blacksea.plamobi W/System.err:     at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:269)
07-27 22:33:58.407 18632-18632/com.blacksea.plamobi W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
07-27 22:33:58.407 18632-18632/com.blacksea.plamobi W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
07-27 22:33:58.407 18632-18632/com.blacksea.plamobi W/System.err:     at java.lang.Thread.run(Thread.java:818)

【问题讨论】：

你能发布这是如何创建 Observable 的吗？ RestService.getPostsByMapProjection(googleMap.getProjection().getVisibleRegion() 会观察On() 新线程吗？
不，它没有。但如果我添加它，什么都不会改变。改造创建的 Observable

标签： android retrofit rx-java retrofit2 rx-android

【解决方案1】：

根据我的经验，java.io.InterruptedIOException 是一个红鲱鱼，因为它通常意味着一些 other 线程取消订阅，并且任何正在运行的线程（fe 网络请求）都会被中断。

在您的情况下，无论是否有错误，每次都会调用RestService.getPostsByMapProjection，这可能不是您想要的行为；考虑将其包装在 Observable.defer() 中

【讨论】：

我将代码更改为：.onErrorResumeNext(Observable.defer(() -> RestService.getPostsByMapProjection(googleMap.getProjection().getVisibleRegion())))，但没有任何变化

【解决方案2】：

您可以在 flatMap 上使用最大并发，以确保您没有任何并发问题

@Beta
public final <R> Observable<R> flatMap(Func1<? super T, ? extends Observable<? extends R>> func, int maxConcurrent) {
    if (getClass() == ScalarSynchronousObservable.class) {
        return ((ScalarSynchronousObservable<T>)this).scalarFlatMap(func);
    }
    return merge(map(func), maxConcurrent);
}

在您的代码中

    LocationService.getUpdatedOrLastKnownLocation(getContext()))
        .flatMap(location -> RestService.getPostsAround(location,0,10),1) //offset = 0, limit = 10;
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(subscriber);

【讨论】：

【解决方案3】：

如果使用了 retrofit2，它的 observables 不会改变它们操作的线程，所以直到 subscribeOn() 之前的所有链都在来自 io 调度程序的单个线程上运行。显然来自 RestService.getPostsAround 的错误为该线程设置了中断标志，并且 okio 在 RestService.getPostsByMapProjection 中阻塞了该标志。您可以尝试在onErrorResumeNext()中的RestService.getPostsByMapProjection之后添加subscribeOn(Schedulers.io())。

【讨论】：

完美，.subscribeOn(Schedulers.io()) 解决了问题。非常感谢。