CreateDerivatives and mini_magic

CreateDerivatives is really slow. I'm also seeing LOADS of mini_magick* and magick* temp files in /tmp. Uploading 17 PDFs took ages.

Tried this mini_magick config in `config\initializers\mini_magick.rb

config.cli = :imagemagick
config.timeout = 5 # oops five seconds!

was posix_spawn

See https://github.com/minimagick/minimagick

but not sure that made any difference

an alternative is VIPS (as per posts by jrochkind).

Fixed locally, consider moving to here.

Fix was to bypass minimagick for PDFs and just use imagemagick. VIPS would be even quicker but is not a standard Centos package.