Reentrant flag is used to control the concurrent execution of methods with in the entity beans.

  1. If reentrant is defined as true in the entity bean deployment descriptor, multiple clients can connect to the Entity bean and execute methods within the entity bean concurrently. And J2ee Container takes care of synchronization.
  2. If reentrant is defined as false in the entity bean deployment descriptor, and many clients tries to connect to Entity Bean concurrently to execute a method, exception is thrown.