具有更多注入的EJB实例的无状态EJB [英] Stateless EJB with more injected EJBs instances

问题描述

我知道无状态EJB存储在一个池中并根据需要实例化，我的问题是，当存在更多的EJB依赖关系(例如，像这样的东西)时会发生什么?

@Remote
@Stateless
public class Master_EJB{
     @EJB
     private EJB_A ejb_A;

     @EJB
     private EJB_B ejb_B;
}

EJB_A和EJB_B也是无状态EJB.

在最坏的情况下，如果完全同时存在两个请求，则服务器将从池中检索Master_EJB的两个实例(或在需要时创建).

但是，如果从这两个调用中，一个只需要EJB_A，而另一个只需要EJB_B，则需要多少个实例:4(2个Master_EJB + 1 EJB_A + 1 EJB_B)或6(2个Master_EJB + 2 EJB_A + 2 EJB_B )?

解决方案

EJB_A和EJB_B是无状态还是有状态?

如果为无状态，则答案取决于所使用的容器/池类型和最近的情况(请求数，服务器负载等). 如果有状态和容器将实例化2个Master_EJB实例，则将实例化EJB_A的两个实例，并且还将实例化EJB_B的两个实例.

请记住，容器可以创建两个Master_EJB实例-它再次取决于容器本身和当前情况(同样，容器可能决定仅使用一个Master_EJB实例来处理请求)./p>

I know Stateless EJBs are stored in a pool and instantiated as needed, my question is, what happens when there are more EJB dependencies, for example with something like this:

@Remote
@Stateless
public class Master_EJB{
     @EJB
     private EJB_A ejb_A;

     @EJB
     private EJB_B ejb_B;
}

With EJB_A and EJB_B also being stateless EJBs.

In the worst case, if there are two petitions at exactly the same time, the server will retrieve two instances of Master_EJB from the pool (or create if needed).

But if from those two calls, one only needs the EJB_A and the other only the EJB_B, how many instances are needed: 4 (2 Master_EJB + 1 EJB_A + 1 EJB_B) or 6 (2 Master_EJB + 2 EJB_A + 2 EJB_B)?

解决方案

EJB_A and EJB_B are stateless or stateful?

If stateless, answer depends on container/pool type used and recent situation (number of requests, server load and so on). If stateful and container will instantiate 2 Master_EJB instances, then two instances of EJB_A will be instantiated and also two instances of EJB_B will be instantiated.

Please bear in mind that container may create two Master_EJB instances - it depends on container itself and the current situation again (as well, container may decide to process request using only one Master_EJB instance).

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