Co-routines are almost trivial with threads.

#! perl -slw
use strict;
use threads qw[ yield ];
use threads::shared;
use Thread::Queue;


my $Q = Thread::Queue->new;

sub complexGenerator{
    my( $max ) = @_;

    for( 1 .. $max ){
        # Do our complex generation here

        # wait till they are ready for the next result
        select undef, undef, undef, 0.01 and yield
                while $Q->pending;

        # and let them have it
        $Q->enqueue( $_ );
    }
    # Indicate we're done
    $Q->enqueue( undef );
}

my $coro = threads->new( \&complexGenerator, 100 );

while( my $next = $Q->dequeue ) {
    # Process latest result set
    printf $next; <stdin>;
}

$coro->join;

__END__
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