use strict;

my $foo = 0;
sub leaky
{
   my $closure = sub { $foo++ };
   return $closure;
}

my $x = leaky();
my $y = leaky();
print $y->(), $/ while $x->() < 10;
----
1
3
5
7
9
[download]

------
We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

The output is correct, but it eats up memory. If you keep looping on that sub, your machine will go into swap.

I tried

my $foo;

sub leaky {
    my $closure = sub { $foo++ };
}
for (;;) {leaky}
[download]

Courage, the Cowardly Dog

Sorry, my mistake. They have to be nested anonymous subs, like this:

my $foo = 'asdf' x 1000;

for (1..900000) {
    my $outer_sub = sub {
        my $inner_sub = sub { $foo };
    }
}
[download]

You're right.

I think this code should be fed to 'perlbug' utility.

Although I seem to remember it was discussed in p5p list somehow, such closure leaks were almost went away just before 5.6.0, but they were too evil to fix.

Courage, the Cowardly Dog