# ...
if ( ($line =~ /notice/) && ($line =~ /rdy/) )

    # Spaces to commas
    $line =~ s/ /,/g;
    
    # Get rid of "notice", "[", "mpmstats:", and tabs inside the line.
    $line =~ s/notice|\[|mpmstats:|\t//g;

    # Change the dreaded Triple Comma into the nice and smooth Single Comma.
    $line =~ s/,,,/,/g;
      # Or even the following if you want to replace all multiple subsequent commas by
      # just one:
      # $line =~ s/,,+/,/g;

    # Show me what I've got
    print $line;
}