Use of select in client.py line 908 forces a limitation of 1024 connections, at least on Linux machines. Furthermore, when the limit is reached it is not reported because it is intercepted by line 912 (ValueError).

See http://stackoverflow.com/questions/14250751/how-to-increase-filedescriptors-range-in-python-select/14250961#14250961 for more information on the connection limit of select