Building Scalable and High-Performance Java™ Web Applications Using J2EE™ Technology

Parallelism

Conceptually, parallelism is the notion of doing more than one task at once. Many parallel machines exist and have been used for research and for processing scientific data sets, but it's probably safe to say that the majority of Web applications don't run on parallel infrastructures. Nevertheless, many can benefit from parallelism on several levels. The key challenge is to understand what aspects of a particular application demand parallelism and what the options are. We'll visit techniques for increasing parallelism later in this book, but first let's define the types of parallelism that exist.

First, there are two parts of any application where parallelism can be extracted —in hardware and in software—and each offers a variety ...