use strict; use warnings; use MCE; open my $sample_fh, '>', 'sample.txt' or die "open error: $!"; open my $good_fh, '>', 'good.txt' or die "open error: $!"; # tybalt89's technique running parallel # see https://www.perlmonks.org/?node_id=1221387 MCE->new( chunk_size => '1m', max_workers => 4, use_slurpio => 1, input_data => 'test.txt', user_func => sub { my ( $mce, $slurp_ref, $chunk_id ) = @_; local $_ = ${ $slurp_ref }; MCE->print($sample_fh, join("\n", /^sample\s+(\S+)/gm), "\n"); MCE->print($good_fh, join("\n", /^good\s+(\S+)/gm ), "\n"); } )->run; close $sample_fh; close $good_fh;