COM & .NET Component Services

Object Pooling

The idea behind object pooling is just as the name implies: COM+ can maintain a pool of objects that are already created and ready to serve clients. The pool is created per object type; different objects types have separate pools. You can configure each component type pool by setting the pool parameters on the component’s properties Activation tab (as shown in Figure 3-3). With object pooling, for each object in the pool, you pay the cost of creating the object only once and reuse it with many clients. The same object instance is recycled repeatedly for as long as the containing application runs. The object’s constructor and destructor are each called only once. Object pooling is an instance management technique designed to deal with the interaction pattern of Internet clients—numerous clients creating objects for every request, not holding references on the objects, but releasing their object references as soon as the request processing is done. Object pooling is useful when instantiating the object is costly or when you need to pool access to scant resources. Object pooling is most appropriate when the object initialization is generic enough to not require client-specific parameters. When using object pooling, you should always strive to perform in the object’s constructor as much as possible of the time-consuming work that is the same for all clients, such as acquiring connections (OLEDB, ADO, ODBC), running initialization scripts, initializing external devices, ...