find + xargs has become my go-to "process files in parallel". Tho now I'm wondering if I should be using `-n` instead of `-L`

    #!/usr/bin/env bash
    set -e

    main() {
      if [ "$1" = "handle-file" ]; then
        shift
        handle-file "$@"
      else
        find . \
          -type f \
          -not -path '*/optimized/*' \
          -print0 \
          | xargs \
            -0 \
            -L 1 \
            -P 8 \
            -I {} \
            bash -c "cd \"$PWD\" && \"$0\" handle-file \"{}\""
      fi
    }

    handle-file() {
      echo "handle-file $1 ..."
    }

    main "$@"