The socket module make a great effort to be thread-safe, but misses one 
big point - it uses single per-instance buffer to hold resolved 
sockaddr_xxx structures. Therefore, on SMP system it is possible that 
several threads calling functions that perform address resolution in 
parallel will stomp on each other resulting in incorrect or invalid address 
to be used in each case.

For example, two threads calling sendto() in parallel can result in packets 
to be sent to incorrect addresses - packets from thread one from time to 
time will be sent to address requested by thread two and vice versa.

Another, smaller issue is that the call to getnameinfo() is not protected 
with netdb mutex on systems that don't have thread-safe resolver.