Re: few newbie quesitons..

["Jay Buffington" <suppressed>]

I'm a little behind here, but this thread caught my eye:

On 5/6/07, Perrin Harkins <suppressed> wrote:
> On 5/6/07, James. L <suppressed> wrote:
> > my question is
> > once the app produce the html, does the memory
> > allocated by the parsed data get released to perl?
> > that memory will be reused by other mod_perl app?
>
> No, Perl doesn't work that way.  It will keep that memory allocated
> for that variable unless you undef the variable explicitly.

It's my understanding that even if you explicitly undef a variable,
perl doesn't release the memory.

Here's a demonstration:

suppressed:~$ cat memusage.pl
#!/usr/bin/perl

use GTop ();

print "Base line:\n";
print_mem();

my %squared;
foreach my $num ( 1..500_000 ) {
       $squared{ $num } = $num**2;
}

print "\nAfter using some memory:\n";
print_mem();

%squared = undef;

print "\nAfter undef'ing variable:\n";
print_mem();

sub print_mem {
       my $proc_mem = GTop->new()->proc_mem($$);
       print "size:     " . $proc_mem->size() . "\n";
       print "vsize:    " . $proc_mem->vsize() . "\n";
       print "resident: " . $proc_mem->resident() . "\n";
       print "share:    " . $proc_mem->share() . "\n";
       print "rss:      " . $proc_mem->rss() . "\n";
}


suppressed:~$ perl memusage.pl
Base line:
size:     7180288
vsize:    7180288
resident: 2936832
share:    1916928
rss:      2932736

After using some memory:
size:     58142720
vsize:    58142720
resident: 49774592
share:    1941504
rss:      49774592

After undef'ing variable:
size:     58142720
vsize:    58142720
resident: 49774592
share:    1941504
rss:      49774592