messages from one client are processed simultaneously about netty-socketio

[mrniko]

I would recommend you to use ack (acknowledgment of received data) https://github.com/mrniko/netty-socketio-demo/blob/master/server/src/main/java/com/corundumstudio/socketio/demo/AckChatLauncher.java
So you will send next message only then ack of recieved message sended by server to client. Because if you send it to server right after first message this leads to many waiting threads on server as a result, which will cause a performance degradation on server.

[ctpahhik]

Unfortunately it's not suitable for us as is. If processing takes 'long' time and acknowledge is sent before processing command we can meet this issue again, if ack is sent after processing we will have significant performance degradation as client will wait for each command to be processed which is not the requirement.
As for me, many threads should process messages simultaneously from different sessions, but messages from one session should be processed consequentially (with one or different threads).
In any case I have to add/use some mediator queue for commands either in my code or in your library. I'd prefer library.
If you are going to left such behavior as "feature" :) please give some advice where I could start to implement it within your lib.

[mrniko]

I'll add new option in Configuration class for this mode.

[ctpahhik]

Thank you very much!
Will look forward for it.

[mrniko]

But keep in mind, in case of using XHRPollingTransport like in your case or websockettransport if client don't get ping from server in certrain time interval it will drop connection. What do you think to fix this?

[ctpahhik]

It's a good question, but our 'long' is expected to be not so long to cause timeout...

Also, as socket.io has reconnection mechanism it may help us in critical cases (actually we never tested if it works for us :) and not sure that will be due to load balancing)
As for me, technical messages may be processed separately but there is few open questions. For example what to do if close session message is received? - close it immediately or wait while previous messages to be processed, etc.
Again, if processing became too long which means that server is overloaded, dropping some connections is not so bed solution, they will be rebalanced to less loaded one.

[mrniko]

Have you tried this simple trick in handler?:
synchronize(client) {
....
}

client instance will be always the same during session.

[ctpahhik]

Yes, I've added synchronization in code and it helps a lot.
We don't have simultaneous execution but as I understand commands reordering is still possible (can't check it for now), so it would be great if you implement feature in question.
In addition if there, for example, 10 clients with 10 commands from each and 5 worker threads there is possibility that all threads take commands from the same client and will be executed one by one, for this time there will be lack of threads for other clients.

[mrniko]

Take a look at this sample:

https://gist.github.com/4692912

I think it's right what you want!

[ctpahhik]

Thanks, it's something I've talked about at the beginning.
It solves thread starvation, but unfortunately doesn't prevent messages reordering :(

[mrniko]

It uses queue, so it should prevent messages reordering. Have you test it?

[ctpahhik]

Yes, messages will be processed in strict order, but they can be put in queue in wrong order the same way as before.
No I haven't tested it yet, will do when have time.
But as usual it's hard to test multi-threading code and it doesn't guarantee that it will work correctly on production. Especially on weird hardware like in our case.

[mrniko]

All messages processed in same order they came. And this https://gist.github.com/4692912 solution allows to queue handlers invocation in right order.