问题
I'm creating a web-service written in Java and hosted on JBoss AS. I'm not a professional in web-service design yet but do I get it correctly and each call to the service initiates a new thread and not a new process? Does it make sense to have synchronized methods in my service? I need to have a method which is invoked only for one user at a time not simultaneously for multiple.
回答1:
Yes, requests are handled by individual handler threads. There is a single process for all of JBoss.
Synchronization can be problematic if your application ends up getting hosted across multiple nodes in a cluster. The locks won't propagate across multiple JVMs without the help of some magic like Terracotta. For a simple solution you can use a pessimistic row lock in your database to control access. One would of course be inclined to challenge the entire design that requires a blocking method and look for an alternative that can run in parallel.
Also, Locks from the java.util.concurrent package are preferred to the synchronized keyword if you are going that route.
来源：https://stackoverflow.com/questions/5904907/does-it-make-sense-to-synchronize-web-service-method