On Wed, 1 Jul 2009 11:15:35 +0100, Paul Thomas <spongelavapaul@googlemail.com> wrote:
Hi,
I've hit a problem as my app has got bigger (about 30-40 widgets now, all chattering roughly once every 2 seconds) where the reliable message delivery mechanism is spiralling out of control. It seems that the constant back and forth means that large 'baskets' of messages are resent. The more this happens, the busier everything gets until the browser becomes unresponsive.
If you can produce a minimal example which demonstrates this behavior, it would probably be very helpful in improving the situation.
There's a fix for it: [Divmod-dev] athena duplicate messages issue but I'm slightly concerned about the potential for lost messages - and also confused about how this could happen. Given that HTTP is a reliable connection-oriented transport, where is the gap that messages can fall through?
Actually, HTTP is not a reliable transport. The most obvious shortcoming it has is that there is no way for a server to know if a client received a response or not, but there are others. So ReliableMessageDelivery is necessary.
I think I can cope with lost messages in most cases, so would it be useful to add a kind of 'sendRemote' that was like 'callRemote' but didn't care about a response? Or maybe this already exists and I've missed it?
This is an interesting idea. I haven't considered having such a feature in Athena before. It may be worth exploring. The first problem that comes to mind is that if any part of a page uses callRemote, sendRemote's advantages are largely lost. This would be because the messages generated by callRemote will still need to be sent, so whatever retransmission logic is present in ReliableMessageDelivery will still be invoked.
Paul.
P.S. this app is likely to get more noisy - is it likely that I'll have to abandon Athena for Orbited or similar? I mean, are there architectural differences that will prevent Athena scaling?
I certainly hope that Athena can handle whatever load you intended to put on it, or that we can work together to fix whatever problems it has which would prevent that. :) Jean-Paul