The select module provides access to platform-specific I/O monitoring functions. The most portable interface is the POSIX function select(), which is available on Unix and Windows. The module also includes poll(), a Unix-only API, and several options that only work with specific variants of Unix.

Using select()

The select module provides access to platform-specific I/O monitoring functions. The most portable interface is the POSIX function select(), which is available on Unix and Windows. The module also includes poll(), a Unix-only API, and several options that only work with specific variants of Unix.

NOte:

Using Python's file objects with select() works for Unix, but is not supported under Windows.

The echo server example from the socket section can be extended to watch for more than one connection at a time by using select(). The new version starts out by creating a non-blocking TCP/IP socket and configuring it to listen on an address.

• select_echo_server.py
• select_echo_multiclient.py

Using poll()

The poll() function provides similar features to select(), but the underlying implementation is more efficient. The trade-off is that poll() is not supported under Windows, so programs using poll() are less portable.

An echo server built on poll() starts with the same socket configuration code used in the other examples.