title: Multithreading in a stateless session bean?
body: <p>The EJB 3.0 specification does not allow a business method of a stateless session bean to create new threads. Why is that? What is wrong with creating additional worker threads that only do raw computations and never call into the app server?</p>
  
  <p>Say, my session bean implements a service that lets users to upload images, and the business method does cpu-intensive image processing on these images. Then it can only use one cpu core to do this job, even if the machine has 8 or more cores? If i utilize a third party image processing library, that internally creates worker threads, i would also violate the EJB specs, even though that library and these threads have nothing to do with the EJB container at all. This does not seem right.</p>
  
  <p>What can happen if i ignore the EJB rules and still create some worker threads to do cpu intensive processing? Of course these threads will never touch any app server objects and the bean thread will join them before returning. Can still something bad happen?</p>