Strange lifecycle callbacks ordering when entering multi-window mode

Question

I'm having a problem with RxJava, Retrofit and Multi-Window mode... I'm calling our own api with Retrofit inside an Activity (the actual code is a little bit more complex than this):

api.getEvent(...)
  .subscribeOn(Schedulers.io())
  .observeOn(AndroidScheduler.mainThread())
  .subscribe(event -> setupUI(event),
             throwable -> showSnackbar(throwable));

When the app is in "normal" mode (full-screen) everything runs fine...I can put the app in bg, put it back to foreground and the api call method is called again (it lies in the onResume method - kind of) and the UI is drawn without problems. When I activate the Multi-Window mode, instead, onResume is called, the api method is called with success but the subscribe() method is never reached. The stacktrace for this situation is:

Retrofit: java.io.InterruptedIOException: thread interrupted
       at okio.Timeout.throwIfReached(Timeout.java:145)
       at okio.Okio$1.write(Okio.java:77)
       at okio.RealBufferedSink.flush(RealBufferedSink.java:221)
       at com.squareup.okhttp.internal.framed.Http2$Writer.flush(Http2.java:381)
       at com.squareup.okhttp.internal.framed.FramedConnection.newStream(FramedConnection.java:283)
       at com.squareup.okhttp.internal.framed.FramedConnection.newStream(FramedConnection.java:249)
       at com.squareup.okhttp.internal.http.Http2xStream.writeRequestHeaders(Http2xStream.java:135)
       at com.squareup.okhttp.internal.http.HttpEngine$NetworkInterceptorChain.proceed(HttpEngine.java:710)
       at com.facebook.stetho.okhttp.StethoInterceptor.intercept(StethoInterceptor.java:67)
       at com.squareup.okhttp.internal.http.HttpEngine$NetworkInterceptorChain.proceed(HttpEngine.java:695)
       at com.squareup.okhttp.internal.http.HttpEngine.readResponse(HttpEngine.java:576)
       at com.squareup.okhttp.Call.getResponse(Call.java:287)
       at com.squareup.okhttp.Call$ApplicationInterceptorChain.proceed(Call.java:243)
       at com.squareup.okhttp.Call.getResponseWithInterceptorChain(Call.java:205)                                                                     at com.squareup.okhttp.Call.execute(Call.java:80)
       at com.newrelic.agent.android.instrumentation.okhttp2.CallExtension.execute(CallExtension.java:43)
       at retrofit.client.OkClient.execute(OkClient.java:53)
       at com.newrelic.agent.android.instrumentation.retrofit.ClientExtension.execute(ClientExtension.java:42)
       at retrofit.RestAdapter$RestHandler.invokeRequest(RestAdapter.java:326)
       at retrofit.RestAdapter$RestHandler.access$100(RestAdapter.java:220)
       at retrofit.RestAdapter$RestHandler$1.invoke(RestAdapter.java:265)
       at retrofit.RxSupport$2.run(RxSupport.java:55)
       at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:428)
       at java.util.concurrent.FutureTask.run(FutureTask.java:237)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
       at retrofit.Platform$Android$2$1.run(Platform.java:142)
       at java.lang.Thread.run(Thread.java:761)

The app doesn't crash but the UI stays in a "placeholder" state and the loading ProgressBar goes forever.

EDIT: I have the same code structure in other activities. The issue doesn't appear nowhere else though.

Answer 1

There's a bit strange sequence of lifecycle callbacks happening when an app enters into multi-window mode. I've logged onStart, onResume, onPause and onStop. See results:

pause
stop
start
resume
pause

So, first initially opened app loses focus, then it gains focus and later it loses focus again (focus goes to the next window).

I believe you are unsubscribing in onPause, because you initiated subscription in onResume. And that's why subscribe() never happens to be called, because it is being unsubscribed immediately.