Hi,
I have seen situations where my mDNSResponder (765.50.9) seems to be busy (blocking one core) and not responding to a
DNSServiceGetProperty(kDNSServiceProperty_DaemonVersion, &uiDaemonVersion, &size);
call.
The high CPU and the blocking of the daemon stopped when I attached the debugger - so this is still a mystery.

But for the first step I wondered why the call is blocked on the client side.
While examining the blocking a stumbled across the following function

static int set_waitlimit(dnssd_sock_t sock, int timeout)
{
    int gDaemonErr = kDNSServiceErr_NoError;

    // To prevent stack corruption since select does not work with timeout if fds > FD_SETSIZE(1024)
    if (!gDaemonErr && sock < FD_SETSIZE)
    {
        struct timeval tv;
        fd_set set;

        FD_ZERO(&set);
        FD_SET(sock, &set);
        tv.tv_sec = timeout;
        tv.tv_usec = 0;

IMHO the conditon
sock < FD_SETSIZE
is wrong, as my sockets are larger that FD_SETSIZE (==64) and this limit only describes the number of socket in the fd_set, not the socket handle itself.

Any opinion to this?
Thanks
Tobias