my $dbh = DBIx::Threaded->connect("DBI:mysql:database=$database;host=$host", $user, $password);
DBIx::Threaded->dbix_threaded_create_pool(10);

my $sth = $dbh->prepare("SELECT id,domain,DATE(created) FROM domain_list");
$sth->execute();

my $counter = 0;
 
while (my @row = $sth->fetchrow_array())
{
	my $id = $row[0];
	my $domain = $row[1];
	my $created = $row[2];
	next unless $row[0..3];
	my $thr = threads->create(mx_lookup,$id,$domain,$created,$dbh) unless $counter >= $thread_no;
	$thr->detach && $counter++ if $thr;
}
$sth->finish();

sub mx_lookup {
	my $id = shift;
	my $domain = shift;
	my $date_c = shift;
	
	my @date_c = split /-/, $date_c;
	my $delta = Delta_Days(@date_c,@date);
	my %emails_in;
	my %emails_out;
	
	if ($delta <= 30)
	{
		my @mx = mx($domain);
		#add multiple mxs support here
		my $mx_count = @mx;
 		my $mx = $mx[0]->exchange;
		
		#find the last change for the given domain
		my $sth = $dbh->prepare("select max(id),domain_id,changed_from,changed_to,date from mx_history where domain_id=?"); #this is where the script fails
		$sth->execute($id);
		
		my @row = $sth->fetchrow_array();
		$sth->finish();
	}
}
	
##</code><code>##

Thread 43 terminated abnormally: Error:Unexpected db_prepare request: must be connected to do that.