Use full processing power with perl

Question

I have a perl script which is running correct but it is only using 1 core of my 2 core CPU, how can i make it utilise all cores.

I know that i can create threads using threads->new(); but how do i fit that into something like:

my $twig= new XML::Twig::XPath(TwigRoots => {TrdCaptRpt => \&top_level});
$twig->parsefile($file);

where the subroutine is being called by something else.

Answer 1

The standard approach with Perl is to not try to use multiple cores with one invocation of the script, but instead to run jobs in parallel on separate cores.

Yes, you can use threading with Perl, but Perl's threading is (very) heavyweight. To avoid potential race conditions, when you spawn a thread Perl simply copies everything that it does not want to explicitly share. Therefore using threading is likely to be much slower than not.

Answer 2

You would need to modify the code of XML::Twig. There is no canned answer of what would need to be done. if you find yourself having to run this script for multiple files, a better and very simple option, is to write your script so it can run for more than 1 file at the same time. You could do that with threads or you could do that with a wrapper script that executes 2 copies of your script at the same time (perhaps with xargs?).