Listen Sockets

Connections between the server and clients happen on a listen socket. Each listen socket you create has an IP address, a port number, a server name, and a default virtual server. If you want a listen socket to listen on all configured IP addresses on a given port for a machine, use 0.0.0.0, any, ANY, or INADDR_ANY for the IP address.

When you install Sun Java System Web Server, one listen socket, ls1, is created automatically. This listen socket uses the IP address 0.0.0.0 and the port number you specified as your HTTP server port number during installation (the default is 80). You cannot delete the default listen socket. If you are not using virtual servers, this one listen socket is sufficient. However, if you are using virtual servers, you may want to create multiple listen sockets for your virtual servers.

Since a listen socket is a combination of IP address and port number, you can have multiple listen sockets with the same IP address and different port numbers, or with different IP addresses and the same port number. For example, you could have 1.1.1.1:81 and 1.1.1.1:82. Additionally, you could have 1.1.1.1:81 and 1.2.3.4:81, as long as your machine is configured to respond to both these addresses.

In addition, you specify the number of acceptor threads (sometimes called accept threads) in the listen socket. Acceptor threads are threads that wait for connections. The threads accept connections and put them in a queue where they are then picked up by worker threads. Ideally, you want to have enough accept threads so that there is always one available when a new request comes in, but few enough so that they do not provide too much of a burden on the system. The default value is 1. A good rule is to have one accept thread per CPU on your system. You can adjust this value if you find performance suffering.