......
my $env=new BerkeleyDB::Env
	-Home=>'/home/XXX/DB',
	-Flags=>DB_CREATE|DB_INIT_MPOOL
|| die;
my $db=tie(%hash,"BerkeleyDB::Btree",
	-Filename=>"URL.db",
	-Flags=>DB_CREATE,
	-Env=>$env)
|| die;
while(1){
	while(my ($k,$v)=each %hash){
		if($num == $coro_max){
			&coro_url;
		}
		else{
			++$num;
			push(@pages,$k) if($k ne '');
		}
	}
}
......