A really simple test: 

foreach ( 1 .. 10000000 ) { 
    my $i = 1;
}
print $i, "\n";

[download]

Run this test. It will take a few seconds, so don't panic. You'll notice that despite creating $i ten million times, you're not actually using ten million times more memory than had you declared $i outside the loop. This is because $i falls out of scope and gets garbage collected each time the loop iterates. If Perl failed to reclaim that memory, you would start seeing a lot of swapfile activity resulting in hard-drive churning, as your internal memory gets saturated and your operating system begins looking to the swapfile for virtual memory. This isn't happening though, because you're reusing memory.

You'll also notice that you're unable to print $i, after exiting the loop. This also is because $i is no longer in scope, and has been garbage collected.... nothing left to see.


Dave

In reply to Re: Two Questions on "my" by davido
in thread Two Questions on "my" by C_T

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