#! /usr/bin/perl -w
use strict;
use warnings;
use Devel::Leak;

while(1) {
  my $count = Devel::Leak::NoteSV(my $foo);
  print "$count";
  <>;
  my $bar;
  $bar = \$bar;
}
[download]

What I can't get working is the extended debugging promised by the Devel::Leak documentation. All I get is a count, and from CheckSV, the cryptic "new 0x5a18b0".

#! /usr/bin/debugperl -w
use strict;
use warnings;
use Devel::Leak;

my $foo;
my $countdown = 10;
while($countdown--) {
  my $count = Devel::Leak::NoteSV($foo);
  print "$count";
  <>;
  my $bar;
  $bar = \$bar;
}
my $count = Devel::Leak::CheckSV($foo);
print "End $count\n";
[download]

Prints

2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
new 0x5a18b0 : 
End 2610
[download]

Even though I've got a debugging perl from Debian:

debugperl -V
Summary of my perl5 (revision 5 version 8 subversion 8) Characteristic
+s of this binary (from libperl): 
  Compile-time options: DEBUGGING MULTIPLICITY PERL_IMPLICIT_CONTEXT
                        PERL_MALLOC_WRAP THREADS_HAVE_PIDS USE_64_BIT_
+ALL
                        USE_64_BIT_INT USE_ITHREADS USE_LARGE_FILES
                        USE_PERLIO USE_REENTRANT_API
[download]

What I can't get working is the sv_dump() mentioned in the Devel::Leak documentation. And when I'm debugging a 100000+ line plus application, that will be crucial.

That I am unlikely to be able to help you with. I don't have Perl built with debugging.

At a random guess, you need to both have a debugging perl and you need to have compiled Devel::Leak against it. If you install a debugging Perl and Devel::Leak using apt-get, I would expect that copy of Devel::Leak to not understand that it has access to debugging information.

The following leaks:

#!./localperl/bin/perl
#
use strict;
use warnings;

use Devel::Leak;

my $handle;
my $count = Devel::Leak::NoteSV($handle);
my $countdown = 10;
while($countdown--) {
  my $bar;
  $bar = \$bar;
}
Devel::Leak::CheckSV($handle);
print "End $count\n";
[download]

It produces: