Hi all.

I'm requesting a little clarification with the concept of a memory leak and reference counting. As I understand it, Perl does not use either 'mark and sweep' or anything resembling the JVM 'garbage collector'. Rather, it increments / decrements reference counts in order to ascertain when memory should be re-claimed. See below: 

my $hash_ref;

   { 
     my %monks = ( 
                   Zaxo        => 'W. Virginia',
                   tye         => 'California',
                   davido      => 'California',
                   theorbtwo   => 'Germany',
                   castaway    => 'Germany',
                   atcroft     => 'Georgia',
                   nothingmuch => 'Israel',
                   rozallin    => 'England',
                 );

     my $hash_ref = \%monks;
   }

[download]


When this block ends, the %monks hash is no longer in scope so the memory it occupied is re-claimed. However, since $hash_ref was not declared inside the block and it has been initialized with the address of the %monks hash, it remains in scope (thereby creating a memory leak)?

One may still perform a variety of operations on the hash reference (and consequently the hash itself). Is this correct? To reduce the reference count to 'zero' (eliminating any potential memory leak that is present), I could simply set the $hash_ref variable to 'undef'(?)

Thanks,

~Katie

In reply to Memory leaks and reference counting within Perl. by DigitalKitty

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