#! perl -sw
use threads;

my $n = 0;
while( 1 ) {
    ++$n;
    my $obj1 = Class->new();
    my $obj2 = Class->new();
    warn "\nMAIN[0]: Creating thread $n passing objs: $obj1 & $obj2\n";
    threads->create( \&thread_sub, $obj1, $obj2, 0 );
    sleep 10;
}

sub thread_sub {
    my( $obj1, $obj2, $level ) = @_;
    warn "THREAD[@{[ threads->tid ]}] L:$level running\n";
    sleep 2;
    threads->create( \&thread_sub, $obj1, $obj2, $level + 1 ) unless $level;
    sleep 2;
    warn "THREAD[@{[ threads->tid ]}] L:$level finished\n";
    threads->self->detach;
}

1;

package Class;
use threads::shared;

my %refcounts;

sub new {
    my $pkg = shift;
    my $this = {};
    bless $this, $pkg;
}

sub CLONE {
    warn ">CLONE[@{[ threads->tid ]}]:\n";
    my $this = shift; # not applicable
    warn "<CLONE[@{[ threads->tid ]}]: this; $this\n";
}

sub DESTROY {
    warn ">DESTROY[@{[ threads->tid ]}]:\n";
    my $this = shift;
    warn "<DESTROY[@{[ threads->tid ]}]: this: $this\n";
}

1;

##</code><code>##

C:\test>junk10

MAIN[0]: Creating thread 1 passing objs: Class=HASH(0x2683c0) & Class=HASH(0x2c4e50)
>CLONE[1]:
<CLONE[1]: this; Class
THREAD[1] L:0 running
>CLONE[2]:
<CLONE[2]: this; Class
THREAD[2] L:1 running
THREAD[1] L:0 finished
>DESTROY[1]:
<DESTROY[1]: this: Class=HASH(0x3c6dc78)
>DESTROY[1]:
<DESTROY[1]: this: Class=HASH(0x3c6dcc0)
THREAD[2] L:1 finished
>DESTROY[2]:
<DESTROY[2]: this: Class=HASH(0x3d34148)
>DESTROY[2]:
<DESTROY[2]: this: Class=HASH(0x3d34178)
>DESTROY[0]:
<DESTROY[0]: this: Class=HASH(0x2c4e50)
>DESTROY[0]:
<DESTROY[0]: this: Class=HASH(0x2683c0)

MAIN[0]: Creating thread 2 passing objs: Class=HASH(0x2683c0) & Class=HASH(0x268120)
...