Bug 471543

SUMMARY
When a tool samples a hidden, color-labeled filter layer Krita starts leaking significant amounts of memory.

STEPS TO REPRODUCE
1. Open a large image (width/height of a few thousand pixels)
2. Create the following layer structure:
  - Filter layer (Color Adjustment Curves, hidden, labeled red)
  - Background (labeled red)
  - Empty layer
3. Set the fill tool to sample the red layers
4. Select the empty layer and start spamming the fill tool

OBSERVED RESULT
After spamming the fill tool a couple dozen times, the memory usage will spike by multiple gigabytes, and that memory won't be freed even if you close the image and open a different one. The memory doesn't seem to be categorized anywhere in the memory indicator, showing up in the total memory used, but not in any of the categories.

EXPECTED RESULT
The memory usage should stay relatively constant

SOFTWARE/OS VERSIONS
macOS Ventura (13.2)

ADDITIONAL INFORMATION
- The same issue occurs with the Fill Tool, Contiguous Selection Tool, or Similar Color Selection Tool
- The issue occurs with any filter I tested (Color Adjustment Curves, Levels, Blur)
- The issue doesn't occur when the filter layer is visible
- Setting the filter layer to visible and using the fill tool again doesn't clear the leaked memory
- The issue doesn't occur when the filter layer is hidden and the fill tool is set to sample the merged image