Book Image

Delphi High Performance - Second Edition

By : Primož Gabrijelčič
5 (1)
Book Image

Delphi High Performance - Second Edition

5 (1)
By: Primož Gabrijelčič

Overview of this book

Performance matters! Users hate to use programs that are not responsive to interactions or run too slow to be useful. While becoming a programmer is simple enough, you require dedication and hard work to achieve an advanced level of programming proficiency where you know how to write fast code. This book begins by helping you explore algorithms and algorithmic complexity and continues by describing tools that can help you find slow parts of your code. Subsequent chapters will provide you with practical ideas about optimizing code by doing less work or doing it in a smarter way. The book also teaches you how to use optimized data structures from the Spring4D library, along with exploring data structures that are not part of the standard Delphi runtime library. The second part of the book talks about parallel programming. You’ll learn about the problems that only occur in multithreaded code and explore various approaches to fixing them effectively. The concluding chapters provide instructions on writing parallel code in different ways – by using basic threading support or focusing on advanced concepts such as tasks and parallel patterns. By the end of this book, you’ll have learned to look at your programs from a totally different perspective and will be equipped to effortlessly make your code faster than it is now.
Table of Contents (15 chapters)

Parallel Task

The Parallel Task pattern is conceptually very simple – it runs the same code on multiple background threads. As with almost all other OTL high-level patterns, a new instance is created by calling the appropriate factory function – in this case, that is Parallel.ParallelTask, which returns an IOmniParallelTask interface. Similar to most OTL patterns, it implements functionality to catch and report exceptions, features a cancellation mechanism, and most importantly for our example, triggers a notification method when the last background worker stops execution.

A parallel task was designed to speed up a longer operation without having to deal with background threads, notifications, and so on. Because of that, by default it works in blocking mode, just like the Join pattern. Similarly, we can call NoWait on the interface and turn it into an asynchronous pattern.

To demonstrate the pattern – and a few other OTL-specific features – I have...