Simple example to get you started:

#! perl -slw
use strict;
use threads;
use Thread::Queue;

sub threadA {
    my $Qab = shift;
    for( 1 .. 1e6 ) {
        $Qab->enqueue( 1+int rand 1000 );
    }
    $Qab->enqueue( undef );
}

sub threadB {
    my( $Qab, $Qbc ) = @_;
    while( my $in = $Qab->dequeue() ) {
        $Qbc->enqueue( $in * 10 );
    }
    $Qbc->enqueue( undef );
}

my $Qab = new Thread::Queue;
my $Qbc = new Thread::Queue;

threads->new( \&threadA, $Qab )->detach;
threads->new( \&threadB, $Qab, $Qbc )->detach;

print while defined( $_ = $Qbc->dequeue );

print 'Done';
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