InterruptedException not caught on RxJava onError callback?

Question

I have a simple code below

    compositeDisposable.add(Observable.create<Int> { Thread.sleep(1000) }
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe({}, {Log.d("Track", it.localizedMessage)}, {}))
    Handler().postDelayed({compositeDisposable.clear()}, 100)

It purposely use Thread.sleep(1000) , just to trigger the InterruptedException . I purposely delay 100 milliseconds, so that ensure the sleep in the chain has started, and dispose it.

(Note, I know using of Thread.sleep is not preferred. I'm just writing this code to test and understand why onError is not called on this scenario, and how to prevent the crash elegantly without need to use try-catch in the RxJava chain)

At that time, when it is triggered, the error is not cause onError (ie doesn't reach the Log . But instead it throws the below error and crash the App.

io.reactivex.exceptions.UndeliverableException: java.lang.InterruptedException
    at io.reactivex.plugins.RxJavaPlugins.onError(RxJavaPlugins.java:366)
    at io.reactivex.internal.operators.observable.ObservableCreate$CreateEmitter.onError(ObservableCreate.java:74)
    at io.reactivex.internal.operators.observable.ObservableCreate.subscribeActual(ObservableCreate.java:43)
    at io.reactivex.Observable.subscribe(Observable.java:11194)
    at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeTask.run(ObservableSubscribeOn.java:96)
    at io.reactivex.Scheduler$DisposeTask.run(Scheduler.java:463)
    at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:66)
    at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:57)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:301)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at java.lang.Thread.run(Thread.java:764)
 Caused by: java.lang.InterruptedException
    at java.lang.Thread.sleep(Native Method)
    at java.lang.Thread.sleep(Thread.java:373)
    at java.lang.Thread.sleep(Thread.java:314)
    at com.elyeproj.porterduff.AnimateDrawPorterDuffView$startAnimate$1.subscribe(AnimateDrawPorterDuffView.kt:45)
    at io.reactivex.internal.operators.observable.ObservableCreate.subscribeActual(ObservableCreate.java:40)
    at io.reactivex.Observable.subscribe(Observable.java:11194) 
    at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeTask.run(ObservableSubscribeOn.java:96) 
    at io.reactivex.Scheduler$DisposeTask.run(Scheduler.java:463) 
    at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:66) 
    at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:57) 
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) 
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:301) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
    at java.lang.Thread.run(Thread.java:764) 

Why was't the InterruptedException caught by the onError in RxJava?

Answer 1

As per pointed by @akarnokd, in https://github.com/ReactiveX/RxJava/wiki/What 's-different-in-2.0#error-handling, looks like the RxJava has been disposed before the throw, hence the error thrown later got through. To address the issue just need to register

 RxJavaPlugins.setErrorHandler { e -> /*Do whatever we need with the error*/ }