[KPhotoAlbum] Performance problem with viewing images

Robert Krawitz rlk at alum.mit.edu
Wed Nov 7 02:23:52 CET 2007


   Date: Wed, 07 Nov 2007 01:45:54 +0100
   From: =?ISO-8859-1?Q?Jan_Kundr=E1t?= <jkt at flaska.net>

   Robert Krawitz wrote:
   > If I have, say, 1000 images in the thumbnail viewer and click on one
   > of them to view it, it takes about a minute for even the first one to
   > pop up.  If I pre-select only a few images, it's reasonably quick.
   > Has the preloading mechanism changed recently?

   Hi Robert,
   as you've already found out, it did. However, the change should have had
   the opposite effect to what you're describing. Previously, the
   full-sized image would have to wait before all the thumbnails are
   generated, but now it should be decoded at first.

I think the problem is the caching that the viewer does.  It tries to
preload a bunch of images, and each of those is put on the queue at
high priority -- i. e. ahead of the one you're actually trying to view.

   I can't really reproduce your issue. I've set thumbanil size to a
   few pixels, sought to the middle of my collection (so that
   thumbnails were loading in the background), selected several rows
   of them and pressed enter to show them. They appeard in a few
   seconds, which isn't perfect, but is far from one minute, and they
   appeard earlier than all thumbnails were decoed in the thumbnail
   widget.

It doesn't matter how big the thumbnails are.  If you select just a
few rows of them, you won't see this effect, since the number of
queued up images will be small.  You need to select a thousand or so.

   The ideal solution would be a priority queue, indeed. This is
   something I have on my TODO list :), but I haven't managed to
   implement before 3.1.0.

   So, how can I reproduce your issues?

Given all this thread stuff, it may well be system dependent.  I have
a single, single core processor.  I could well believe it would behave
differently on a dual core processor, or with a different thread
library.

Load a few thousand images into the thumbnail viewer and then just
double click one of them should do the trick.

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lpf at uunet.uu.net
Project lead for Gutenprint   --    http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton


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