Is there anything missing that compiling with -DDEBUGGING would add?
Yes, if your perl had been built with -DDEBUGGING, Devel::Leak would
call its (then available) routine sv_dump() on the things in
question, which would produce output similar to what you'd get with the
module Devel::Peek. How much that helps, though, will depend
on the particular situation...
Anyhow, most problems with memory leaks in Perl code are related to
circular references. Consider the following
for (1..1000000) {
my $h = {};
$h->{myself} = $h;
}
This harmlessly looking piece of code consumes about 130MB (on my
machine). Reason is that the anonymous hashes (referenced by $h)
are not being freed, because they're holding a reference to themselves,
so their reference count doesn't drop to zero when the $h goes
out of scope...