Gallery too slow or hanging for large image collections

Agreed. The mobile gallery apps are very fast. I would love to be able to ditch Apple for storing my photos.

i installed the preview-generator-program from the “store” and (re-)generate all previews with a nightly cronjob. i have ~100GB of pictures and the cronjob takes ~150mins. the previews take up ~83GB (!!!) in /data/appdata_ocjecx05wt96/preview but the gallery really is amazingly fast with it (before that, it wasn’t useable at all.)
so if you have the diskspace and can spare some computing cycles, i’d say it’s really worth a try.

Enhance your config.php:

'preview_max_x' => 512,
'preview_max_y' => 512, 
'preview_max_scale_factor' => 1,

Then follow this guide and your previews will jump up as popcorn.

~ 50GB of photos leads to 3,9GB of thumbs.


Would you be so kind to tell where exactly mentioned lines of codes go in Generate.php and PreGenerate.php? I see a class (Generate and PreGenerate respectively) and can’t really decide in which function do they fit and what they will do (they possibly go into parseFile and processFile but I’m not a php wizard myself so not really sure).

Beside that, is it possible that you say a word about the difference between preview:generate-all and preview:pre-generate?

Thank you in advance!

Ok, for the second question I found this:
It says:

preview:generate-all: Loop over all files and try to generate previews for them…

preview:pre-generate: Do the actual pregeneration. This means only for new or modified files (since the app was enabled or the last pregeneration was done).

the previews are very nice and fast once generated, but generation itself is pushing my system to its limits.

  1. the dir containing the previews has about the same size as the all the pictures together (110GB)
  2. generation takes 7+hrs/nite and increasing (cronjob) - even if there are no new pictures
  3. pre-generate does not work on my system (was finished after 2 secs but did not create any previews)
    is there any way this could be fixed? if i delete the huge preview-dir i am afraid re-genration will take DAYS)

sudo /snap/bin/nextcloud.occ preview:pre-generate
is returning immediately for me too (it doesn’t appear to do anything)
I tried adding -vvv and still nothing is shown and it exits right away.

sudo /snap/bin/nextcloud.occ preview:generate-all
is doing something :slight_smile:

You should make sure to use the update command in your crontab since it can’t take more then a second if there are no new images to generate.

This and opcache + local cache APCu are a must for big library’s.

Of course first time generation can take a while depending on library size and processing power.

After that it should be mega fast.

One issue I still walk in too is that sometimes the gallery will just stop loading images in half way. It gets stuck on the loader at the bottom and when clicked I get jumped back one directory. This might be a Ajax problem, I will soon try other update methods.

Both the apps for Android and iPad keep giving major issues loading content off any types, but especially the image heavy directories make the app freeze. This is horrible unusable, which is a shame. I decided to just use the web app in most cases.

I feel like this might be a WebDAV issue, and nextcloud might have to think of a different engine for syncing files over.

I’m not sure if I had a similar issue or the same. When I scrolled through the pictures maybe the tenth picture took about 1 minute to load. Some pictures were fast again and suddenly another one was extremely slow.
I figured I had error messages about file locks in the system logs/ journal and that this was caused by Redis not working. Once I got Redis fully working, this issue stopped. No more files were locked by mistake or too long.