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Stack trace is opaque for IllegalStateException: Exception thrown on Scheduler.Worker thread. Add `onError` handling.

See original GitHub issue

This occurs when using RxAndroid 0.23.0/RxJava 1.0.0, please redirect me if this is not the most appropriate place for this.

There seem to be a several ways to cause the following exception, notably using observeOn() on a when there exists overproducing or underconsuming, and there is no clear association with client code:

java.lang.IllegalStateException: Exception thrown on Scheduler.Worker thread. Add `onError` handling.
       at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:50)
       at android.os.Handler.handleCallback(Handler.java:733)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at android.os.Looper.loop(Looper.java:146)
       at android.app.ActivityThread.main(ActivityThread.java:5598)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
       at dalvik.system.NativeStart.main(NativeStart.java)
Caused by: rx.exceptions.OnErrorNotImplementedException
       at rx.Observable$31.onError(Observable.java:7204)
       at rx.observers.SafeSubscriber._onError(SafeSubscriber.java:127)
       at rx.observers.SafeSubscriber.onError(SafeSubscriber.java:96)
       at rx.internal.operators.NotificationLite.accept(NotificationLite.java:147)
       at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.pollQueue(OperatorObserveOn.java:177)
       at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber.access$000(OperatorObserveOn.java:65)
       at rx.internal.operators.OperatorObserveOn$ObserveOnSubscriber$2.call(OperatorObserveOn.java:153)
       at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:45)
       at android.os.Handler.handleCallback(Handler.java:733)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at android.os.Looper.loop(Looper.java:146)
       at android.app.ActivityThread.main(ActivityThread.java:5598)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
       at dalvik.system.NativeStart.main(NativeStart.java)
Caused by: rx.exceptions.MissingBackpressureException
       at rx.internal.util.RxRingBuffer.onNext(RxRingBuffer.java:222)
       at rx.internal.operators.OnSubscribeCombineLatest$MultiSourceProducer.onNext(OnSubscribeCombineLatest.java:201)
       at rx.internal.operators.OnSubscribeCombineLatest$MultiSourceRequestableSubscriber.onNext(OnSubscribeCombineLatest.java:252)
       at rx.internal.operators.OnSubscribeTimerPeriodically$1.call(OnSubscribeTimerPeriodically.java:51)
       at rx.Scheduler$Worker$1.call(Scheduler.java:118)
       at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:45)
       at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:422)
       at java.util.concurrent.FutureTask.run(FutureTask.java:237)
       at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:152)
       at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:265)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
       at java.lang.Thread.run(Thread.java:841)

I’d like to strike up a discussion highlighting common causes on these backpressure exceptions, how to determine the source of them in client code, and finally how to improve the stacktrace.

Issue Analytics

State:
Created 9 years ago
Comments:21 (10 by maintainers)

Top GitHub Comments

8reactions

akarnokdcommented, Nov 28, 2016

The problem is this:

.subscribe( action );

You have to handle exception by consuming it via subscribe:

.subscribe( action, error -> errorHandler(error) );

3reactions

corlaezcommented, Oct 1, 2016

I am toying with RxJava and I had this issue as well. I think ReactiveX should be very careful to explain the difference between Observable.doOnError (side effect, will still blow up) and Subscriber.onError (last consumer, if handled here your error won’t pop anymore. At least that was my problem. https://twitter.com/Corlaez/status/782023068793339904

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