Asynchronous File I/O on Linux

[richard.pieri-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org (Richard Pieri)]

On May 16, 2010, at 2:30 PM, Mark Woodward wrote:
> 
> While I can see your point, it would be impossible to do multiple simultaneous requests without some sort of asynchronous I/O capability.  The "random access" aspect of it comes out of using multiple file handles to a single file.

Not true.  read() and friends usually block until the read completes or an error occurs.  If you open() a file with O_NONBLOCK then the read() call returns an error if there is nothing ready to be read.  This gets you nowhere near parallel reads, but it does get you a polling loop that chews up CPU while effectively blocking your program anyway.


> Besides, you probably mean O_RDWR or O_RDONLY, O_WRONLY won't work in your example.

Probably. :)

--Rich P.