Running up-to-date PS 22.2 and ACR 13.1 on macOS 10.14.6
When opening camera raw files via PS it will open majority of the images but not all. If you hit cancel it will then opening the remaining images.
A particular example folder I have been testing with is all just the same camera with 144 images. 138 will open initially and then when you hit cancel the remaining 6 will open.
If I open the folder in Bridge and then select all to open in ACR all 144 will open at once.
ACR runs outside Photoshop memory/address space, and doesn't use the scratch disk. Sounds like it runs out of memory.
If you need to work on that many images, use Lightroom. It's specifically designed for high volume work. ACR is more intended for single (or a few) images.
So this was tested on two different machines one with 16GB or Memory and the other with 32GB.
Each time it was the same 138 that opened then followed by the remaining 6.
Based off that I don't see how that could be a memory issue. Especially since I can open all 144 in one ACR window when accessing them via Bridge.
As for the your statement regarding Lightroom and ACR. Lightroom is just the browser interface and calls on the same ACR engine iirc.
I have also never heard of or seen any recommendation before about how many files you can load up in ACR. Do you have any documentation I can reference for that?
Lightroom is not "just a browser interface". It is not a browser at all, in fact. The catalog organization makes it much more streamlined and effective for volume processing, because it doesn't have to write to each individual file, like ACR does.
Obviously there is no limit to how many files you are "supposed" to open in ACR. But it does have limited memory resources given the way it works.
Nobody is stopping you from trying to open 144 files at the same time in ACR. But it will be an upstream swim, fighting the application instead of working with it.
However that is not an option for large scale photo offices. Lightroom's catalog can only be accessed by one machine at a time, which is exactly why we need to have those color correction adjustments saved to the sidecar file.
Do you have any documentation regarding the "limited memory resources" of ACR? I would be very interested to see if there is a way that we should be adjusting our workflows.
Just for your reference, our ingests that we process range from 500-2000 images which we have been using ACR for years to do color adjustments with.
No, I don't have any documentation, but I do know that ACR - as indeed all plugins - run outside Photoshop's address space. In other words, it uses its own memory separate from Photoshop.
If Photoshop has a high memory allocation setting in preferences, that limits the memory available for other applications, including ACR.
which is exactly why we need to have those color correction adjustments saved to the sidecar file.
Not sure if it will help, but you can set Lightroom to "automatically write changes into XMP" in the catalog settings. This will create XMP files for proprietary raw files.
One other thing to try: In ACR preferences > performance > GPU, choose "custom" and then uncheck "use GPU for image processing".
There is an acknowledged bug in Lightroom where it uses excessive amounts of video RAM (VRAM) with this setting. I assume ACR works he same way here.
This high VRAM usage doesn't normally have any noticeable ill effects, but who knows with so many files open.