ExoPlayerSimpleView updating not on the ui thread and crushing the app

[OfekRegev]

when the exoplayer is attached to the PlaybackControlView and the player is prepared and ready to play then when I'm calling player.setPlayWhenReady(true) not from the ui thread I get this crush -

android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:6817)
at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:940)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:360)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:360)
at android.view.View.requestLayout(View.java:18794)
at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:360)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.requestLayout(View.java:18794)
at android.view.View.setFlags(View.java:10638)
at android.view.View.setVisibility(View.java:7437)
at android.widget.ImageView.setVisibility(ImageView.java:1497)
at com.google.android.exoplayer2.ui.PlaybackControlView.updatePlayPauseButton(PlaybackControlView.java:639)
at com.google.android.exoplayer2.ui.PlaybackControlView.access$1100(PlaybackControlView.java:172)
at com.google.android.exoplayer2.ui.PlaybackControlView$ComponentListener.onPlayerStateChanged(PlaybackControlView.java:1078)
at com.google.android.exoplayer2.ExoPlayerImpl.setPlayWhenReady(ExoPlayerImpl.java:171)
at com.google.android.exoplayer2.SimpleExoPlayer.setPlayWhenReady(SimpleExoPlayer.java:627)
at com.music.ofek.iplay.Services.PlayerService.handleMessage(PlayerService.java:173)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:148)
at android.os.HandlerThread.run(HandlerThread.java:61)

[andrewlewis]

Discussed with @tonihei. We'll look at posting to the main thread for these callbacks. Thanks for reporting this!

[OfekRegev]

I have updated my issue comment. this is happening when using PlaybackControlView, I'm using PlaybackControlView and not SimpleExoPlayerView. I don't know if it's happening on SimpleExoPlayerView either so it's for you to check it out too.
@andrewlewis

[andrewlewis]

This may actually need to be fixed in a different way (TBD).

Out of interest, would it be feasible for you to move all calls to the player onto your app's main thread? If this is difficult it would be useful to know why. Thanks.

[OfekRegev]

It's exactly what I did. but it's an error prone to do so because of 2 reasons -

1. It's much harder for me to know which method of the player will directly update the view and which not.
2. If I'm forgetting to do so anywhere in my code and it won't be found in the QA(which it's happening from time to time) even 1 call could crash my app.

as I see it it's much easier for you to manage the threads for the UI operations than it for me...

[tonihei]

Thanks for the feedback. In the current version, we always require to access the player from one thread only (see here (under "threading model") for a summary of our requirements).

From what you describe it seems your app should be using the main thread to make the call to setPlayWhenReady.

And, unfortunately, our UI components do not support using the player from any background thread at the moment. We need to establish how common this usage pattern is first, before deciding whether or not we are going to handle such situations.