| Subject: | Circular references causing memory leaks |
Hi.
You've got a few circular references in your code, and a few memory leaks as a result.
For example:
my $media = Net::SDP::Media->_new( $self, $value );
...
push( @{$self->{'media'}}, $media );
You store a reference to a Net::SDP::Media object in the Net::SDP object, but you also store a reference to the Net::SDP object in the Net::SDP::Media object. Circular reference. Neither object gets destroyed because both contain references to one another. Here:
for (1..300000) {
my %hash_one = (
foo => 7,
bar => 8,
hash_two => undef
);
my %hash_two = (
baz => 15,
hash_one => \%hash_one
);
$hash_one{hash_two} = \%hash_two;
}
print "Done.\n";
Run that code and watch it hang at the end. The hashes don't get cleaned up after each iteration of the loop because their reference counts never dropped below zero. It's only at the very end when Perl does global destruction that they get cleaned up, all 500,000 of them at once.
Comment out this line:
$hash_one{hash_two} = \%hash_two;
and see the difference.
Here's an article on all of this:
http://www.perl.com/pub/a/2002/08/07/proxyobject.html
Basically, %parent can contain references to %child, but not %child cannot contain any references to %parent. I know, this sucks, but it's either that or leak memory.