o_append with Perlbal::AIO?

Brad Fitzpatrick brad at danga.com
Tue Mar 20 01:00:22 UTC 2007

It's not going to happen:  the kernel doesn't support it, and there's no
locking between all the IO::AIO or Linux::AIO worker threads.

You need to serialize the writes yourself (which is easy, since Perlbal's
a single-threaded event loop!), and just make sure you only have one
aio_write() outstanding at a time.  We do this already, for instance, in
the buffered upload writing to /tmp/.  When the one outstanding aio_write
completes, we see if we have another to do, and kick the next one off.
(which might already be merged from several writes that came in while the
real write was outstanding)

On Mon, 19 Mar 2007, EKC wrote:

> Howdy,
> For the life of me, I can't seem to figure out how to do AIO o_append
> in Perlbal. I'm using Perlbal::AIO, which is using Linux::AIO from
> What I would like to do, is to use o_append to log the activity of a
> custom Perlbal hook that I am developing. However, the only file
> writing operations supported by Linux::AIO and IO::AIO seem to be
> sendfile and aio_write, neither of which appends bytes atomically to
> the end of a file.
> I have multiple concurrent processes appending to the same file, and I
> would like to use AIO and o_append to be able to atomically AND
> asynchronously append to the file from within Perlbal.
> Is there any way to use o_append with Perlbal::AIO (or IO::AIO, or
> Linux::AIO) that I'm overlooking? Is there a better way of getting
> asynchrounous atomic o_append support into Perlbal?
> Thanks in advance!
> BTW, Perlbal rocks!

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