Real async file IO on Linux?

[Dane Foster]

I don't have a pressing need for async IO at the moment but it's one of the
many new features of Java that I have plans to exploit in the future. If the
nio-dev community doesn't get around to it before I need it I'll be happy to
contribute code. So thank you very much for pointing out exactly where I
need to begin, in the event that I actually end up needing to hack on this.

Dane Foster
CTO & Chief Architect
Reservation Systems Online, LLC.


On Thu, Jul 28, 2011 at 2:38 PM, Alan Bateman <Alan.Bateman at oracle.com>wrote:

> **
> Dane Foster wrote:
>
> Alan,
>
>  I completely & totally agree w/ Tim. I would love to see true non
> buffered async IO support instead of the emulation of async IO. The current
> implementation reminds me of green threads from way back when, in that they
> never actually addressed the issue of fully utilizing a SMP (or in today's
> terminology, multi-core) system, it just gave the programmer the illusion
> that it did (w/ the added cost of being slow and inefficient), in the same
> way that the current async IO implementation is an illusion of true async
> IO. I never said anything before because I had assumed that the emulation
> mechanism was a fallback mechanism for when async IO support was not
> available on a platform. I did not realize, until this thread started, that
> platform async IO support meant the buffered case to you.
>
> As I said, there's nothing here to preclude supporting non-buffered I/O and
> patches are always welcome on nio-dev. The place to plug this in is in
> UnixChannelFactory.newAsynchronousFileChannel which can select the
> implementation to use based on the open options. In the Windows case then it
> already selects an implementation based on the Windows asynchronous I/O API.
> As per prior discussions on the nio-* lists then there isn't any guarantee
> on the alignment of direct buffers and in addition information to allow
> applications size and get appropriately aligned file offsets would need to
> be considered. Nothing particularly hard to implement but clearly something
> for advanced developers.
>
> -Alan.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.openjdk.java.net/pipermail/nio-discuss/attachments/20110728/f7e2cbae/attachment.html