Setting a thousand of artworks takes a lot of time

[arturdryomov]

The title sounds ridiculous but it is true.

Since the source I’m working on contains a limited set of images I ship a defined set of declarations in JSON. It contains something like 1500 elements. I read this JSON, transform it to Artwork objects and call MuzeiArtProvider#setArtwork. It works fine but there is a noticeable delay before images actually appear on the UI. It might take almost a minute to do so (on a real device). Timings from an emulator:

Step	Time
Reading JSON	69 ms
Transforming to Artwork	23 ms
MuzeiArtProvider#setArtwork	3.514 s
Timeout before images appear	16 s

One thing I’ve noticed right away is a ton of such log entries:

D/MuzeiArtProvider: Notified for batch change on content://ru.ming13.muzei.earthview/1342
D/MuzeiArtProvider: Notified for batch change on content://ru.ming13.muzei.earthview/1341
D/MuzeiArtProvider: Notified for batch change on content://ru.ming13.muzei.earthview/1340

Not sure it is necessary to occupy the thread with logging 1.5 K entries, especially taking into account Uri#toString calls. But the real issue is somewhere else and it occupies the majority of time.

[ianhanniballake]

We've removed the unconditional logging (it is now tied behind Log.isLoggable() with the MuzeiArtProvider tag) and Muzei 3.4.0 (currently in alpha) drastically improved the loading logic when it comes to that initial huge set of artworks.

[arturdryomov]

Just tried 3.4.0 — the improvement is here, thanks!

However, I’ve increased the artworks count to 2600+ and there is still a visual pause. It’s not as bad as it was though:

Step	Time, ms
Reading JSON	126
Transforming to Artwork	25
MuzeiArtProvider#setArtwork	10061

These numbers are from Google Pixel 3a with Android 10 onboard. Timings were taken from the onLoadRequested method. The call was done when I’ve chosen the source in Muzei. Seems like artworks appear when the setArtwork is done.

Not sure if it’s possible to optimize this further.