The Lifecycle of a Stateless Session Bean
The lifecycle of a stateless session bean is very simple. It has only two states: Does Not Exist and Method-Ready Pool. The Method-Ready Pool is an instance pool of stateless session bean objects that are not in use. Because of all the injection and such that can happen, it can be more efficient to save stateless bean instances when they are not in use. This is an important difference between stateless and stateful session beans; stateless beans define instance pooling in their lifecycles and stateful beans do not.[8] Figure 5-2 illustrates the states and transitions an SLSB instance goes through.
Figure 5-2. Stateless session bean lifecycle
The Does Not Exist State
When a bean is in the Does Not Exist state, it is not an instance in the memory of the system. In other words, it has not been instantiated yet.
The Method-Ready Pool
Stateless bean instances enter the Method-Ready Pool as the container needs them. When the EJB server is first started, it may create a number of stateless bean instances and enter them into the Method-Ready Pool. (The actual behavior of the server depends on the implementation.) When the number of stateless instances servicing client requests is insufficient, more can be created and added to the pool.
Transitioning to the Method-Ready Pool
When an instance transitions from the Does Not Exist state to the Method-Ready Pool, ...
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