If you’re a Rails developer working on Mac OS X 10.6, you may have seen this message:
Ruby threads cannot be used in RubyCocoa without patches to the Ruby interpreter
It is caused by a plug-in or gem requiring osx/cocoa, frequently attachment_fu. AttachmentFu can use CoreImage as an image processor instead of calling out to an image manipulation library such as ImageMagick or GD2.
The warning is harmless, but it can be very noisy. To disable it, you can simply remove CoreImage from AttachmentFu’s list of image processors by creating a new file in config/initializers. Its contents should be this one line:
Image resize operations will now use one of the other image processors, which you can install from MacPorts. I never deploy to a Mac OS X server for production, and I prefer to run as much of the same code as possible in development, so this isn’t a problem for me.