IO::AIO module implements asynchronous I/O using whatever means your
operating system supports. It is implemented as an interface to the libeio
library: http://software.schmorp.de/pkg/libeio.html.
.
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.
.
While most of this works on all types of file descriptors (for
example sockets), using these functions on file descriptors that
support nonblocking operation (again, sockets, pipes etc.) is
very inefficient. Use an event loop for that (such as the L<EV>
module): IO::AIO will naturally fit into such an event loop itself.
.
In this version, a number of threads are started that execute your
requests and signal their completion. You don't need thread support
in perl, and the threads created by this module will not be visible
to perl. In the future, this module might make use of the native aio
functions available on many operating systems. However, they are often
not well-supported or restricted (GNU/Linux doesn't allow them on normal
files currently, for example), and they would only support aio_read and
aio_write, so the remaining functionality would have to be implemented
using threads anyway.
.
Although the module will work in the presence of other (Perl-) threads,
it is currently not reentrant in any way, so use appropriate locking
yourself, always call poll_cb from within the same thread, or never
call poll_cb (or other aio_ functions) recursively.
