Lightroom: loops rendering standard previews

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  • Updated 7 years ago
After removing the previews folder, I asked LR to render standard previews for all my photos (17,416). It went into a loop when it came to a file named _MG_6323_Edit.tif . I had to close LR to stop it. I then restarted LR and repeated the rendering request, and it worked away for some time before eventually looping on another of my edited tif files. This has happened 4 times so far, and I have 4448 images remaining to render. LR doesn't loop twice on the same image.

I examined all the looping tifs and the same context applies. They are all cases where I developed a raw image, then edited it in photoshop, then created a virtual copy of the edited version back in LR, then cropped that. This results in two tif files with the same name listed by LR in Library mode (if unstacked).

I think this looping is a bug.

E6600 2.4 GHz dual-core cpu
6GB memory
windows 7/64-bit
Lightroom 3.4.1
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peter facey

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Posted 7 years ago

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Dan Tull, Employee

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If you export a catalog with just that edited TIF and its virtual copy and invoke the render previews command, will it happen again the first time you do it?

If there's a repeatable case which is small enough to zip up and send me the files to set it up, I'd love to corner this bug. We've had occasional reports of preview rendering getting jammed up intermittently, but never one that's so specific.
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peter facey

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Thanks.

Sadly, it isn't repeatable after an export. I just tried exporting the folder and images where it first looped, and also exporting several folders and 800 images leading up to the point of looping, but neither reproduced the problem.

I tried running an integrity check on my existing catalog: it did not report any problems (although I'm not sure if LR reports problems during an integrity check).

My existing catalog was exported when I moved from LR2 to 3 as recommended at that time. And it has been optimised recently, so presumably LR3 thinks it's in good shape.

I'll experiment a bit more over coming days, but think I may not be able to get a small export that reproduces this.
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Dan Tull, Employee

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Rats. I'd hoped it was just a matter of a certain sort of settings, but it sounds like something much more subtle, which matches with how elusive this bug has been in the past, unfortunately.

If it does still happen with some reliability in the original catalog, there might be some logging that we could enable which would provide some clues, though quite a bit less so than a repeatable case obviously.

I just had a thought actually. Do you have very many other virtual copies with different develop settings? Maybe this is the result of an exception getting thrown, possibly due to the underlying file being still in use. This gives me an idea for a possible way to recreate this condition.

When you say "loop" do you mean LR is busy (high CPU usage) but making no progress like it's rendering the same photo again and again, or does the progress bar just stop making progress so it just stops advancing?
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peter facey

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In the cases where it looped, I think there was only one virtual copy of that image.
I have a very small number of images where there may be 2 or 3 virtual copies, but those didn't feature in the looping. It doesn't loop on all vcs.

When looping, utilisation of my dual-core cpu is 90 to 100% and LR makes no further progress (the image count in the bar at top left doesn't change). But it will exit in a civilised manner if I click the X. It will also CANCEL the render task if I tell it to. Restarting the render, with or without restarting LR, causes it to resume on the image following the one looped.

One thing I was thinking of doing is exporting the whole 17,000 images to a USB disk and see if it happens there, but I haven't made the effort yet. If it did, I could post it to you.
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Dan Tull, Employee

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Hmm. I've got a few ideas I want to try in order to repro this bug. Until then, I don't want to ask any more of you. Thanks again for the detailed report, here's hoping it gives me the clue I need to corner this issue.