Oracle GlassFish Server 3.0.1 Administration Guide

About Thread Pools

The Virtual Machine for the Java platform (Java Virtual Machine) or JVM machine) can support many threads of execution simultaneously. To help performance, GlassFish Server maintains one or more thread pools. It is possible to assign specific thread pools to connector modules, to network listeners, or to the Object Request Broker (ORB).

One thread pool can serve multiple connector modules and enterprise beans. Request threads handle user requests for application components. When GlassFish Server receives a request, it assigns the request to a free thread from the thread pool. The thread executes the client's requests and returns results. For example, if the request needs to use a system resource that is currently busy, the thread waits until that resource is free before allowing the request to use that resource.