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)

Variable capturing

Before I start writing parallel code, I have to cover something completely different. As you’ll see in this chapter, a big part of the incredible usefulness of tasks and patterns is the ability to use them in combination with anonymous methods and variable capturing. As powerful as that combination is, however, it also brings in some problems.

The code in this chapter will frequently run into the problem of capturing a loop variable. Instead of trying to explain this problem at the same time as dealing with the already hard concepts of parallel code, I decided to write a simple program that demonstrates the problem and does nothing more.

The code in the AnonMethod project tries to write out the numbers from 1 to 20 in a convoluted way. For each value of i, the code calls TThread.ForceQueue, and passes in an anonymous method that calls Log(i) to write the value into ListBox.

The problem with the following code lies in the programmer’s assumptions...