7 - Concurrent programming

Summary

Today's computers have multi-core processors (i.e., integrated circuits to which two or more processors have been attached), which, in principle, allow the concurrent execution of computer instructions. In other words, today's computers are able to perform two or more tasks at the same time. Concurrent programming refers to the design and implementation of programs that consist of interacting computational processes that should be executed in parallel. In addition, concurrent programming is not only the next logical step in software development, but the next necessary step. Thus, all modern programming languages must provide constructs and libraries that will ease the construction of concurrent programs. Scala allows users to design and implement concurrent programs using either threads, or mailboxes or actors. Unfortunately, programming with threads is a cumbersome task, thus, concurrent applications in Scala are usually implemented using the actor model of programming.

Programming with threads: an overview

Roughly, a process is a program loaded into memory that is being executed. A thread, also known as a lightweight process, is a basic unit of processor utilization. Processes may include more than one thread while traditional processes include only one thread. Threads may effectively communicate but since they share a process's resources (for example, memory and open files), their communication is not without problems. Each Scala program has at least one thread while several other “system” threads take care of events in GUI applications, input and output, etc.