I am using Perl 5.8.5,

Try upgrading your perl.

I see no memory leaks at all on my system under both:

• Perl v5.8.9(32-bit) threads v1.71 threads::shared v1.27 Thread::Queue v2.11

  Memory usage goes directly to 262.6MB and stays exactly there.

• Perl v5.10(64-bit) threads v1.71 threads::shared v1.26 Thread::Queue v2.11

  Memory usage goes directly to 262.4MB and stays exactly there.

Update: Probably irrelevant as this is only demo code, but you are doing some mighty peculiar things.

1. There is no need to share my $q : shared       = Thread::Queue->new();

   They are created shared.

2. Why are you creating your big strings inside 1-element anonymous arrays:

   while ( my $v = ["this is a test" x 250] ) {
   [download]

   to then pluck it out and push it onto your shared array:

   push @$ary, $v->[0];
   [download]

There is weirdness with your whole architecture, but it's pointless debugging a demo app. If you can post the real code, or a sanitised but still representative example, then I would take a look at that.