Performance tips for Spring based WS on Glassfish

Hello,

I assumed this is the right place to ask because of many libraries/solutions used. I've WebService created with Spring (annotation based). WebService runs on glassfish v2.2 server and is preceeded by Apache server load-balancer. WebService itself validates SOAP request and pushes data from it to JMS queue. It's rather simple thing.

Problem was with performance - clients were able to shot more requests to the server than it could process at a time. So during the load-tests with SoapUI I assumed that using @Oneway annotation to perform async requests would be great idea (and it is - 400% performance boost). The problem with @Oneway though, is that it can't return any value and throw any Exception. So that could be potentially dangerous to not see if something is going wrong. So besides releasing new WSDL with additional async method, I want to tune Spring/Apache/Glassfish performance. Any ideas what look for or change? I have full access to configuration - Glassfish serves only as WebService server and JMS consumer. Spring is 3.0.6 and Apache is 2.2.13. Tips/resources/posts wolud be highly appreciated.

Thanks in advance,
Michal Piotrowski