Hello
I've written a server for a proprietary UDP protocol that needs to answer with
exactly one packet for every incoming packet. All packets are independent from
each other so that I like to have each one handled asynchronously by a
different thread from a pool with a certain maximum size.
So far I used this:
FooCodec codec = new FooCodec(); // encoder and decoder in one class
InetSocketAddress local = new InetSocketAddress(port);
acceptor = new NioDatagramAcceptor();
acceptor.getFilterChain().addLast("executor", new
ExecutorFilter(maxThreads));
acceptor.getFilterChain().addLast("codec", new
ProtocolCodecFilter(codec, codec));
acceptor.setHandler(handler);
acceptor.bind(local);
At first it seemed that each incoming UDP package, due to its stateless nature,
creates a different Mina "session" and each Mina "session" runs in its own
thread so that the default ExecutorFilter implementation
OrderedThreadPoolExecutor is fine as I certainly don't want the session closed
if there is still a response before it in the queue.
Now under a bit of load, one session was a bit slower and hanging for 1,5s and
it suddenly happened that multiple UDP packets were put into the same
Mina "session" which lead to the following log messages:
2013-09-24 10:56:02,910 DEBUG
org.apache.mina.filter.executor.OrderedThreadPoolExecutor :
Adding event MESSAGE_RECEIVED to session 17529
Queue : [MESSAGE_RECEIVED, , MESSAGE_RECEIVED, , MESSAGE_RECEIVED ... ]
(OrderedThreadPoolExecutor.java:431)
This now completely destroys the asynchronous behaviour as all packeges had to
wait
for the first one in the queue even if there were several executor threads
idling
around!
How should I fix this problem? Using an "UnorderedThreadPoolExecutor?
Or setting acceptor.getSessionConfig().setIdleTime(IdleStatus.BOTH_IDLE, 0);
Or by somehow else force the creation of a Mina "session" for each UDP packet?
Best Regards
-christian-
P.S.: http://mina.apache.org/mina-project/documentation.html contains a
links to a "UDP Tutorial" which sadly refers to a page that does
only have APR and Serial tutorials.
