Lots of thumbnail requests with invalid size

It looks like this seriously affects the user experience too.

Take about 40-50 photos. Run gallery-app. Go to the photo roll.

Scroll up and down until all the thumbnails have been generated. (This loads up the cache.)

Run tail -f ~/.cache/upstart/dbus.log on the phone.

Now scroll up and down in the photo roll.

The trace shows that all the thumbnail requests are made with QSize(-1,-1). The thumbnailer delivers each thumbnail in around 1.5 msec. But the screen shows lots of spinners for quite some time. Presumably, that's happening because all the thumbnails are 1920 in size, but need to be scaled down to the size required on-screen. Asking for the thumbnails in the correct size would make things go considerably faster, I suspect.

Hey Arthur, I saw that you landed some changes recently [1] around thumbnailer use, could you check if that has to do with the issue described there?

[1] https://code.launchpad.net/~artmello/gallery-app/gallery-app-disable_gallery_photo_component/+merge/263818

I'm not seeing any requests for -1 in dbus.log using thumbnailer from silo 10, but we have not changed the code in Photo Roll at all so not sure why the problem is not occuring.

@michi
Would you mind retesting with the latest rc-proposed image with silo 10 installed?

We made a last-minute change to treat invalid QSize requests as 128x128, so the -1, -1 requests no longer show up in dubs.log.

However, if you look in ~.cache/upstart/application-click-com.ubuntu.gallery_gallery_2.9.1.1209.log, you'll see tons and tons of invalid QSize requests.

We are planning on returning an error for these soonish, so it would be good to pass the correct QSize for each thumbnail.

confirmed, seeing the invalid QSize in the gallery log

When we tap in a photo, we are in fact opening a list of media that user can navigate when swiping right and left. The fact that we are seeing requests for videos when opening a photo is related with the way this list cache is implemented in gallery. With the new MR linked here, gallery should not request any thumbnail with (0, 0) but we still could request two videos thumbnails for each video. One for fullscreen and one for not fullscreen mode when in device (on desktop, we should request more sizes), since the sourceSize is linked with window height/width. Let me know if that is good enough or if we should go for a one size fits all approach, requesting a thumbnail big enough (maybe a single (0,0)) and using it as our thumbnail for all the window sizes.

OK, so that explains the video thumbnails, thanks!

I think it's OK to ask for whatever images you actually want to display. I mean, after all, that's what the thumbnailer is for. If you were to always ask for some fixed size, then each and every time the thumbnail needs to be displayed, the GPU has to re-scale it. I suspect that's going to be harder on the battery and on performance than to simply ask for whatever size you want to show. That way, we scale each image only once.

I just downloaded the PPA from silo 4 and tried it on Mako.

I'm still seeing lots of requests with invalid size (-1, -1).

To reproduce, take a few photos and videos, run "thumbnailer-admin clear", and start the gallery-app.

Looking at ~/.cache/upstart/application-click-com.ubuntu.gallery_gallery_2.9.1.1209.log, I see a whole bunch of requests with invalid size when I start the app.

Also, there appears to be another problem. (I'm watching ~/.cache/upstart/dbus.log for this.)

After I have my thumbnails on the events page, I can scroll all they way to the right by swiping left. With the list positioned at the far right, I briefly swipe left again. When I do that, I see that the app fires around twenty requests within about 400 ms, all for the same single image, all at size 256. I don't see why this should be necessary, seeing that the thumbnails being asked for are sitting there on the screen already.

Something similar happens when swipe right to to move the list back to the beginning, and swipe right again. However, there, I see only two requests, for two different thumbnails every time I swipe right. But, again, why are these requests happening, when the widget is already populated with thumbnails?

Pat, are you sure that's really fixed? Three days ago, when I tested from the silo, there were still problems (see comment #8).

Not sure I saw a vivid landing with the bug referenced, reopen if not fixed

OK, I set it back to "Confirmed". I believe the issues in comment #8 are still there. If not, someone please set me straight! :-)

we have released the fix in latest gallery click package 2.9.1.1232
@artmello please verify if the issue in comment #8 is still present

I tested on krillin (r94) with gallery (2.9.1.1232) and I am not able to see any invalid size request. We have multiple requests while loading events with different sizes (none invalid) for the same delegate but that is related with the current implementation of the event list andwe are working to improve that in another MR.
About the issue related with moving to the end/start of an event and when moving seeing multiples requests I can reproduce that and it seems to be fixed with setting the listView cache (currently gallery force it to cache nothing). We are changing that in the same MR I mentioned above.

I don't have a krillilng, only a mako. I can test again with that. I'll grab the latest rc-proposed image and your gallery version. (It's still in the silo, I take it?)

No, it was published. The fix should be on the rc-proposed image already

This bug was fixed in the package gallery-app - 0.0.67+15.10.20150806-0ubuntu1

---------------
gallery-app (0.0.67+15.10.20150806-0ubuntu1) wily; urgency=medium

  [ Arthur Mello ]
  * Fix the use of actionManager.localContexts to match last changes on
    it (LP: #1481920)
  * Fix thumbnail requests with invalid size on Events and Photos tab
    (LP: #1460993, #1467743)

  [ CI Train Bot ]
  * New rebuild forced.
  * Resync trunk.

 -- CI Train Bot <email address hidden> Thu, 06 Aug 2015 21:11:58 +0000

I just tried with image 217 from rc-proposed, and things look much better now. I don't see the invalid sizes anymore.

However, when pulling left when I'm at the end of my event list, I still get multiple requests for the same thumbnail. Right now, I'm seeing 18 requests for the same thumbnail being fired all at once each time I swipe left with the gallery positioned at the far right end.

BTW, the number of duplicate requests seems to depend on the current layout of the event list. Sometimes I see two requests, sometimes five, sometimes a dozen. If you don't see what I'm describing, add a single photo at a time and try again. It seems to be worst when a single photo "sticks out" at the right-hand end of the list.

The repeated reloading of thumbnails is due to gallery-app appending Date.now() to the image://thumbnailer URI. I've put together an MP that should fix this while still requesting new thumbnails when the file contents change here:

https://code.launchpad.net/~jamesh/gallery-app/thumbnail-mtime/+merge/268185

I built a test package that Michi says clears things up for him:

http://people.canonical.com/~jamesh/com.ubuntu.gallery_2.9.1.1234_armhf.click

What do we need to do to get this merged?

Since "requesting the same image multiple times" isn't quite the same problem, I filed bug 1485490 and linked my branch to it there.