Sorry, I have now put the correct debug file in my post above. cheers
initial status of opencl enabled flag is OFF.
Have fun!
Claes in Lund, Sweden
the box to select open cl is not greyed out - can’t you check it? also i’m not a mac person but Mac computers that use OpenCL and OpenGL graphics – Apple Support (UK)
Hi,
I’m really not sure if it could be helpful, but if you haven’t try yet, maybe you could try to pre-generate the thumbnails for your collection in one run instead of letting darktable doing it slowly in the background.
To do so, you just have to run the darktable-generate-cache command in a terminal (on a mac, locate darktable in the application folder, then show the content of the package and then look in the MacOS folder) : darktable 3.8 user manual - darktable-generate-cache
Good luck!
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Possibly you should set a memory limit for tiling. Actually you allow modules to request memory of unlimited size. Default is 1500 MB.
Did you try launching dt with an empty config folder and an empty cache? With all it’s default settings? Do the problems still exist in this case?
Can’t look into the logfile at the moment, back on my computer tomorrow.
Yes do this, the log doesn’t show us much.
I can, but I guess you noticed that that list is archived and not updated for years, and certainly doesn’t include any Silicon Mac models?
Is it still useful to check it when OpenCL is fully deprecated by Apple? On a model of Mac that was released years later?
I will give it a go in the morning, but I am confused about why.
I will try to learn how to do this tomorrow (launch with empty config and cache).
I take it from the responses so far that you guys have nice clean lighttable thumbnails? That would be nice to have.
I have had this problem for years.
I also have more crashing/hanging with DT 3.8 than prior versions. Hopefully it is also related to the settings you have been identifying.
Cheers
oh i’m sorry i should have looked more closely at the list.
Use the --configdir command modifier and point it to a new directory…can be wherever you what it to be…
https://darktable-org.github.io/dtdocs/en/special-topics/program-invocation/darktable/
OK I have turned on OpenCL and set tiling limit to 1500 MB of memory, restarted the Mac and…it is still there, but on first glance there is less of it? That’s promising. Unless it starts to build up the more I use it.
I will now see if I can do the empty launch.
Thanks so far guys.
If you select a raw file that has a black thumbnail, go into darkroom mode, make a small change, then go back to light table, is the thumbnail still black?
That worked.
In fact I am flicking through my recent collections now and not seeing the issue at all. Pretty pleased with this.
You can try running /Applications/darktable.app/Contents/MacOS/darktable-generate-cache in a terminal, with darktable closed. That should regenerate your cache with the updated darktable settings.
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Thanks, all done, 100% of cache images completed. Collections load more quickly too.
Still not 100% gone, though. An example seen just now:-
I wonder if deleting the cache first would help?
Yes, of course.
Frequent hangups or crashes of the application may also damage your database and/or config files.
You told us that your issue exists for years. This means that you may have messed up a lot due to errors and crashes. To check if your basic installation of dt is ok and if it is working trouble-free with default settings, I would strongly recommend to launch dt with empty config (without your databases and settings) and a complete empty cache (see darktable 4.6 user manual - darktable , switches --configdir and --cachedir).
Then import and edit some images and look what happens.
Yes, I think so. That is why I recommend starting with an empty cache.
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I just noticed this issue for the first time today. And only on one photo - same exact computer. Considering you’ve seen this escalate, I’d prefer to nip it in the bud 
The funny thing is I tried the trick of making a small change. Worked perfectly. Went back in and put the slider back to its original setting. And now the black is in a different spot on the photo - and instead of blocks - it’s a nebulous blob. Moves around each time I makes changes.
Figure I’ll try clearing cache/config and generating the thumbs all at once.
For clarification: If I want to empty the cache and config folders - do I just delete the files within the folders? All the files in those folders? Or remove the actual Darktable folders from within config and cache? Does darktable regenerate them upon relaunch? Regardless, I’d back them up before deleting to be safe.
Thanks.
Scott
Not so surprising. You have to find the cause of the issue first. Possibly you have to customize your settings in Preferences → Processing. Clearing the cache is the second step to get rid of precalculated thumbnails containing the black blobs.
Yes. Backup the content of ~/.config/darktable (linux path) first. It contains your databases with all your edits, presets, … Alternatively you can start dt from the commandline and use the switches --configdir /path/to/any/empty/config/folder and --cachedir /path/to/any/empty/cache/folder.
dt creates new config files with default settings (for example dakrtablerc …) and new (empty) databases. Your personal edits and setting are lost of course, as long as darktable does not see your old databases (data.db and library.db) in the config directory you actually use.
The complete cache can be regenerated (based on your data.db and library.db) using the tool darktable-generate-cache. This can take a long time (hours), dependent on the number of edits you have in your database. Make sure darktable-generate-cache terminates with the message Done, otherwise you may have a problem with your database library.db.
Thanks so much for the detailed reply. I’m new to darktable, and appreciate your patience.
Sorry, I should have added more details about my Preferences > Processing settings. Before reading this thread - my Processing tab had some changes from default that I did not personally make. The ‘memory for thumbnail cache’ was set at an odd 71236, which unless I’m reading this wrong, is far more than my computer has. Also, the ‘host memory for tiling’ was set to 8192. I have reset these to the default values listed in the manual (512 and 1500 respectively). Everything else is also set to default settings except: chromatic adaptation set to “modern,” and no ‘auto-apply sharpen.’
I have made backups of the config and cache folders (probably should have skipped the cache folder - I’ll regenerate using the darktable-generate-cache tool). I have been thinking about installing a newer developed build for Mac (3.9.0+35), so this black block/blob issue popping up might be the perfect excuse to give it a try.
Scott