Asynchronous onGetLibraryRoot deadlocks legacy MediaBrowser #3393

Version

Media3 1.11.0

More version details

1.11.0

The same callback works with 1.9.0/1.10.1.

Devices that reproduce the issue

• Pixel 9 with android auto simulator

Devices that do not reproduce the issue

No response

Reproducible in the demo app?

Yes

Reproduction steps

On the demo app, return an incomplete ListenableFuture from MediaLibrarySession.Callback.onGetLibraryRoot().

Complete it successfully from a background thread after 100 ms. Example code:

override fun onGetLibraryRoot(
    session: MediaLibraryService.MediaLibrarySession,
    browser: MediaSession.ControllerInfo,
    params: MediaLibraryService.LibraryParams?,
  ): ListenableFuture<LibraryResult<MediaItem>> {

    val future = SettableFuture.create<LibraryResult<MediaItem>>()
    Log.i("AsyncRootRepro", "Returning incomplete root future")
    executor.schedule(
      {
        Log.i("AsyncRootRepro", "Completing root future")
        future.set(
          LibraryResult.ofItem(
            MediaItemTree.getRootItem(),
            params,
          )
        )
      },
      100,
      TimeUnit.MILLISECONDS,
    )

    return future
  }

Connect a controller like Android Auto. The background log confirms the future completes, but the browser never connects and the service main thread ANRs.

Returning Futures.immediateFuture with the identical LibraryResult (as in the default demo-session sample) works.

Expected result

MediaLibrarySession.Callback explicitly returns a ListenableFuture, so a non-immediate result should complete without deadlocking legacy browser compatibility.

Actual result

Only an already-completed future works. Asynchronous future deadlocks the service main thread.

Media

see ready example on de demo-sesion at https://github.com/kelmer44/media-interstitials/tree/anr-deadlock

Bug Report

• You will email the zip file produced by adb bugreport to android-media-github@google.com after filing this issue.