Austine Jane wrote:

We are going to build a web application and want to know if twisted+nevow fit our situation. Our server has four cpus running. Our web application would require high cpu load sometimes, and a multiple of users might use the system at the same time.

I guess twisted is single threaded server model. How could we make it scale well and make advantage of four cpus? Does it support process farm like scgi server?

Have a frontend service that load balances connections to four or maybe five instances of Twisted. For example LVS, iptables NAT rules, apache or Twisted itself can be used as the load balancer, depending on your needs. In essence, treat your 4 CPUs like you would treat 4 separate machines.