This chapter focuses on improving the socket server performance using a few useful techniques. Unlike the previous chapter, here we consider multiple clients that will be connected to the server and the communication can be asynchronous. The server does not need to process the request from clients in a blocking manner; this can be done independently of each other. If one client takes more time to receive or process data, the server does not need to wait for that. It can talk to other clients using separate threads or processes.

In this chapter, we will also explore the select module that provides the platform-specific I/O monitoring functions. This module is built on top of the select system call of the underlying operating system's kernel. For Linux, the manual page is located at http://man7.org/linux/man-pages/man2/select.2.html and can be checked to see the available features of this system call. Since our socket server would like to interact with many clients, select can be very helpful to monitor non-blocking sockets. There are some third-party Python libraries that can also help us to deal with multiple clients at the same time. We have included one sample recipe using Diesel concurrent library.

Although, for the sake of brevity, we will be using two or few clients, readers are free to extend the recipes of this chapter and use them with tens and hundreds of clients.