foo.p6

#!/usr/bin/env perl6
my str $str = 'abcdefgh' ~ 'efghefgh';
my $imax = 1024 / $str.codes * 1024 * 4;               # 4mb

my $starttime = now;
say "exec.tm.sec\tstr.length";

my str $gstr='';
my $i=0;

while ($i++ < $imax + 1000) {   #adding 1000 iterations to delay exit. This will allow to capture memory usage on last step

        $gstr ~= $str;
        $gstr ~~ s:g/efgh/____/;
        my $lngth = $str.codes * $i;
        say round(now - $starttime), "sec\t\t", $lngth/1024, 'kb' if $lngth %% (1024 * 256); #print out every 256kb
}