I'm using threads and xmlrpclib in python at the same time. Periodically, I create a bunch of thread to complete a service on a remote server via xmlrpclib. The problem is that, there are times that the remote server doesn't answer. This causes the thread to wait forever for a response which it never gets. Over time, number of threads in this state increases and will reach the maximum number of allowed threads on the system (I'm using fedora). 
I tried to use socket.setdefaulttimeout(10); but the exception that is created by that will cause the server to defunct. I used it at server side but it seems that it doesn't work :/
Any idea how can I handle this issue?
It seems like your real problem is that the server hangs on certain requests, and dies if the client closes the socket - the threads are just a side effect of the implementation. If I'm understanding what you're saying correctly, then the only way to fix this would be to fix the server to respond to all requests, or to be more robust with network failure, or (preferably) both.
too many threads due to synch communication