Lighroom Classic 9.1: massive memory/resource leak generating 1:1 previews

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  • Updated 6 months ago
Lightroom and the kernel_task process consume all available memory when generating 1:1 previews, until LR hangs all macOS has compressed every process's memory.  Force quitting LR releases the memory, but things aren't the same without a reboot due to every process having been squeezed out of memory and compressed.

This is LR 9.1 on macOS 10.14.6, with graphics processor usage disabled.  System info:
  Model Identifier: MacBookPro11,3
  Processor Name: Intel Core i7
  Processor Speed: 2.5 GHz
  Number of Processors: 1
  Total Number of Cores: 4
  L2 Cache (per Core): 256 KB
  L3 Cache: 6 MB
  Hyper-Threading Technology: Enabled
  Memory: 16 GB
  Chipset Model: Intel Iris Pro
  Chipset Model: NVIDIA GeForce GT 750M

I always build 1:1 previews on import, but after edits I regenerate them because this seems to help overall performance.  This evening I left it regenerating previews for a few thousands photos and went out for a couple of hours.  Upon return, it was still working, but LR wasn't responding and the system was out of memory.  Pay particular attention to kernel_task:

I had to force-quit LR, and the effect on memory was immediate:

I restarted LR, and then restarted 1:1 preview generation for something like 1,400 photos.  It completed, but memory ended up tight:

I got the memory back after cleanly quitting LR:

Photo of Kath


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Posted 6 months ago

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Photo of Rikk Flohr

Rikk Flohr, Official Rep

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I would recommend a clean install and preference file reset before we collect any data from you.  Here are the instructions: 

. Often times, simply performing a clean reinstall of the latest version of Lightroom will clear the issue similarly eliminating the need to revert.Before reverting to the previous version, try the Lightroom Clean Install Procedure with the current version:
  1. Close Lightroom
  2. Restart the computer
  3. Use the Adobe Creative Cloud App to uninstall Lightroom Classic
  4. Restart the computer
  5. Install Lightroom Classic via the Creative Cloud App without launching any other programs.
  6. Restart the computer
  7. Launch Lightroom
  8. Wait 5 minutes
If performance issues persist after this procedure and reset of your preference file, then it is likely an issue that needs troubleshooting further.A Preference File will survive a Lightroom uninstall/reinstall. Sometimes weird behavior is corrected/cured by resetting the preferences.Reset Procedure:

1. Close Lightroom.
2. Hold down [Alt/Opt]+[Shift] while restarting Lightroom.
3. Overwrite the Preferences when prompted by the dialog.
4. Close Lightroom.
5. Restart Lightroom.Does the performance issue continue after resetting the preferences?

If after performing these two steps you still see rampant memory usage, we will want to collect some log files.