Java，EJB，所有方法的并发锁

Question

I have EJB with two methods

@Singleton(name = "RatingCalculatorEJB")
public class RatingCalculatorBean {

    public void countRating() {}

    public void countRating(int someID) {}
}

By default all methods has concurrency lock: @Lock(LockType.WRITE) If method invoked by any thread - another thread will wait to invoke this method.

But I need more - if any method invoked by a thread, all other threads that call any method of EJB should wait. Does I have any way to do it?

The same question for @Stateless beans

Answer 1

@Lock(LockType.WRITE) locks ALL EJB methods of the bean, so it already does what you want.

Stateless beans only handle one client at a time, so concurrency should rarely be a problem there.

Answer 2

You can try to make that method synchronized. In that way only one thread can access the method at one time.

Answer 3

@Lock(LockType.WRITE) on bean won't lock all methods of the bean. It is same as put @Lock(LockType.WRITE) on each method of the bean.

Annotating a singleton class with @Lock specifies that all the business methods and any timeout methods of the singleton will use the specified lock type unless they explicitly set the lock type with a method-level @Lock annotation. If no @Lock annotation is present on the singleton class, the default lock type, @Lock(WRITE) , is applied to all business and timeout methods.