Permanent 'Temporary failure in name resolution' after running for a number of hours

Question

After running for a number of hours on Linux, my Python 2.6 program that uses urllib2, httplib and threads, starts raising this error for every request:

Answer 1

This was caused by a library's failure to close connections, leading to a large number of connections stuck in a CLOSE_WAIT state. Eventually this causes the 'Temporary failure in name resolution' error due to resource exhaustion.