sub multiplex {
    my @my_array;
    foreach my $entry (@array) {
        open my $fh => ">", $entry->[0].".mu" or die "open: $!";
        push @my_array, [$fh, $entry->[1]];
    }
    open my $fh => $file or die "open: $!";

    while (<$fh>) {
        foreach my $entry (@my_array) {
            print {$entry->[0]} $_ if /$entry->[1]/;
        }
    }

    foreach my $entry (@my_array) {
        close($entry->[0]) or die "close: $!";
    }
}

##</code><code>##

          s/iter multiplex       one
multiplex   1.65        --      -87%
one        0.209      690%        --