Given the following code: 
#!/usr/bin/perl
use strict;

sub handler {
    my %foo=(a=>1,b=>2,c=>3);
    a(\%foo);
    print "A -> $foo{a} B -> $foo{b} C -> $foo{c}\n" ;
}

sub a 
{
    my $ref=shift;
    $ref->{a} = 100;
    my %copy=%$ref;
    $copy{a} = 10;
    my $ptr =\$ref->{b};
    $$ptr = 20;
}

[download]
What is the correct jargon for the 3 separate constructs? I think of them as references, copies and another syntax to do a reference that I think of as pointers.
Another question I have is in regards to performance and memory use:
Given that %foo starts to be 10 or 20 items, and this would be running in mod_perl, I sometimes use the my %foo = %$foo construct to make the syntax easier to type, but it does make a copy. Perl is famous for not giving memory back, so i assume that making a copy in a sub will start to gobble ram if the hash is of appreciable size. At what point does perl free ram used for my() constructs in subroutines? Does it ever? Does it keep it on the perl stack and reuse it?

Similarly, I have a mod_perl based system thats just crazy for ram use. With PerlFreshRestart On, the parents and children grow by 30 megs a day. But, strangely enough, they grow only in the shared section. private section ( difference between ram and shared size) is only about 2 megs per process. It seems that somehow PerlFreshRestart does not re-use the ram allocated for earlier copies of the libraries. I've turned off FreshRestart but it still seems to leak. I SIGUSR1 the process every night for log rotation, and this seems to be when the process memory growth occurs. Anything I can do?
--
Jay "Yohimbe" Thorne, alpha geek for UserFriendly

In reply to A question of memory, mod_perl, and references and subroutines by Yohimbe

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