my $buffer:shared="";
sub PRINT {
 lock $buffer;
 $buffer.=shift;
}

sub dump_on_screen {
 lock $buffer;
 print $buffer;
 $|++;
 $buffer="";
}

##</code><code>##

my $pt=threads->new(\&PRINT_THREAD);
sub PRINT_THREAD {
 dump_on_screen();
}