Introduction to Threading Programming Guide

As multicore computers become more commonplace, running an application that has only one path of execution for code to follow quickly becomes a barrier to performance. In order to take advantage of a computer’s extra cores, an application must break its overall work down into smaller chunks and run those chunks concurrently on separate cores. The low-level technology used to run each chunk is called a thread.

Although this document is ostensibly about using threads in your application, it is important to point out that threads are really just infrastructure. Taking advantage of threads effectively requires you to design your application in a way that supports concurrency. Done correctly, an application should be able to run tasks concurrently and be guaranteed that those tasks execute correctly and with minimal interference. Done incorrectly, an application’s tasks may corrupt each other’s data and potentially cause your application to crash.

This document provides an introduction to concurrency, describes why it is important, and provides design tips for implementing it in Mac OS X applications. This document also describes the relevant Mac OS X technologies (including threads) related to concurrency and provides examples of how to use them.

Because threading and concurrency are advanced programming topics, you should read the information in this book carefully before trying to implement threads in your own applications. You should also consult other texts and Internet resources regarding threading and concurrency in application design.

Organization of This Document

This document has the following chapters and appendixes:

“Concurrency and Application Design” introduces the concept of concurrency and its role in application design.
“Creating and Managing Operation Objects” focuses on the NSOperation object and how you use it to perform tasks concurrently.
“Creating and Managing Threads” provides information about the lower-level technologies used to create and manage threads.
“Synchronization and Thread Safety” describes synchronization issues and the tools you use to prevent multiple threads from corrupting data or crashing your program.
“Run Loop Management” provides information about how to manage event-processing loops in secondary threads.
“Thread Safety Summary for Mac OS X” provides a summary of the inherent thread safety of Mac OS X and some of its key frameworks.

Introduction to Threading Programming Guide

Contents:

Organization of This Document

See Also