Chapter 1. The Joys of Concurrent Programming

"I suspect that concurrency is best supported by a library and that such a library can be implemented without major language extensions."

” Bjarne Stroustrup, inventor of C++

In this Chapter

• What is Concurrency?

• The Benefits of Parallel Programming

• The Benefits of Distributed Programming

• The Minimal Effort Required

• The Basic Layers of Software Concurrency

• No Keyword Support for Parallelism in C++

• Programming Environments for Parallel and Distributed Programming

• Summary ”Toward Concurrency

The software development process now requires a working knowledge of parallel and distributed programming. The requirement for a piece of software to work properly over the Internet, on an intranet, or over some network is almost universal. Once the piece of software is deployed in one or more of these environments it is subjected to the most rigorous of performance demands. The user wants instantaneous and reliable results. In many situations the user wants the software to satisfy many requests at the same time. The capability to perform multiple simultaneous downloads of software and data from the Internet is a typical expectation of the user. Software designed to broadcast video must also be able to render graphics and digitally process sound seamlessly and without interruption. Web server software is often subjected to hundreds of thousands of hits per day. It is not uncommon for frequently used e-mail servers to be forced to survive the stress of a million sent and received messages during business hours. And it's not just the quantity of the messages that can require tremendous work, it's also the content. For instance, data transmissions containing digitized music, movies, or graphics devour network bandwidth and can inflict a serious penalty on server software that has not been properly designed. The typical computing environment is networked and the computers involved have multiple processors. The more the software does, the more it is required to do. To meet the minimal user's requirements, today's software must work harder and smarter . Software must be designed to take advantage of computers that have multiple processors. Since networked computers are more the rule than the exception, software must be designed to correctly and effectively run, with some of its pieces executing simultaneously on different computers. In some cases, the different computers have totally different operating systems with different network protocols! To accommodate these realities, a software development repertoire must include techniques for implementing concurrency through parallel and distributed programming.