Re: avoiding child death by size limit

Perrin Harkins wrote:
> On Fri, Dec 11, 2009 at 11:37 AM, William T <[email protected]> wrote:
>> You can make sure the variables that the memory was malloc'd for have
>> gone out of scope, and there are not trailing references to them.
>> Perl will then reuse that memory.
> 
> It will keep the memory allocated to the out-of-scope variables unless
> you undef them.
> 
> There's a summary of many PerlMonks discussions on this topic here:
> http://www.perlmonks.org/?node_id=803515
> 
Perrin,
that is in the end, in my personal opinion, a rather confusing discussion.

So, to an extent, is your phrase above.
When you say "It (perl) will keep the memory", do you mean that
- the perl interpreter embedded in this Apache child will keep the 
memory (and not return it to the OS), but will re-use it if possible for 
other variable allocations happening within its lifetime ?
or
- the perl interpreter embedded in this Apache child will keep the 
memory (and not return it to the OS), and never re-use it again for any 
other variable allocation happening within its lifetime
(in other words, this is a leak) ?

Does any guru care to provide some simple real-world examples of when 
memory once allocated to a variable is/is not being re-used, in a 
mod_perl handler context ?
Or pointers to ditto ?
(Maybe at first independently of whether the memory also may, or not, be 
returned by Perl to the OS)

Maybe on this last subject, what I gather from this and other 
discussions I've seen, is that once the Perl interpreter obtained some 
memory from the OS, it rarely returns it (before it exits); and if it 
does, it is in any case not practically predictable in a cross-platform 
way, so one cannot rely on it.  Is that a fair interpretation ?


Would it be preferable/easier if I construct some simple examples myself 
and present them here asking if memory allocated to "my $a" is being 
leaked or not ?