Description:

This module implements asynchronous I/O using whatever means your
operating system supports.

Asynchronous means that operations that can normally block your program
(e.g. reading from disk) will be done asynchronously: the operation
will still block, but you can do something else in the meantime. This
is extremely useful for programs that need to stay interactive even
when doing heavy I/O (GUI programs, high performance network servers
etc.), but can also be used to easily do operations in parallel that are
normally done sequentially, e.g. stat'ing many files, which is much faster
on a RAID volume or over NFS when you do a number of stat operations
concurrently.