$master_thread = threads->create( \&sub1, $para );
....
....

sub sub1{
	my $tmp = shift;
        
        ## not work as expected, I don't know why?
	my $sub_thread = threads->create( \&sub2, $tmp );
        ....
        ....
}

sub sub2{
	my $value = shift;
	
	print $value;
}