my $HOW_MANY = shift || 100_000; my ($s, $e1, $e2); $s = time; for ($i=0; $i<$HOW_MANY; $i++) { $q{$i}=1; } $e1 = time - $s; print qq{ Normally, it takes me about $e1 second(s) to put $HOW_MANY items into a hash. Now I'm going to construct $HOW_MANY special keys and see how long it takes to put those into a hash instead. }; undef %q; print "Generating $HOW_MANY keys\n"; my @keys; my $i = 0; while (@keys < $HOW_MANY) { $i++; my %hash = (0 => 0, $i => 0); if (%hash =~ /1/) { # Goes in the same bucket as 0 push @keys, $i; } } print "Putting the $HOW_MANY special keys into the hash.\n"; $i = 0; $lasttime = $s = time; foreach $key (@keys) { $h{$key} = 1; $i++; if (time() - $lasttime > 5) { my $h = %h + 0; print "I have put $i keys into the hash, using $h bucket(s)\n" ; $lasttime = time; } } $e2 = time - $s; print qq{ The $HOW_MANY special keys took $e2 seconds to put into the hash, instead of $e1 seconds. };