Высокая производительность Delphi (черновик перевода глав 1-2) [Примож Габриэльчич] (fb2) читать постранично, страница - 3

explain how to achieve the highest possible speed using data duplication, aggregation, and communication. At the end, I'll introduce two third-party libraries that contain helpful parallel functions and data structures.

Chapter 6, Working with Parallel Tools, focuses on a single topic, Delphi's TThread class. In the introduction, I'll explain why I believe that TThread is still important even in this modern age. I will explore different ways in which TThread based threads can be managed in your code. After that, I'll go through the most important TThread methods and properties and explain what they're good for. In the second part of the chapter, I'll extend TThread into something more modern and easier to use. Firstly, I'll add a communication channel so that you'll be able to send messages to the thread. After that, I'll implement a derived class designed to handle one specific usage pattern and show how this approach simplifies writing parallel code to the extreme.

Chapter 7, Exploring Parallel Practices, moves the multithreaded programming to more abstract terms. In this chapter, I'll discuss modern multithreading concepts: tasks and patterns. I'll look into Delphi's own implementation, Parallel Programming Library, and demonstrate the use of TTask/ITask. We'll look at topics such as task management, exception handling, and thread pooling. After that, I'll move on to patterns and talk about all Parallel Programming Library patterns: Join, Future, and Parallel For. I will also introduce two custom patterns—Async/Await and Join/Await—and finish the chapter with a discussion on the Pipeline pattern from OmniThreadLibrary.

Chapter 8, Using External Libraries, admits that sometimes Delphi is not enough. Sometimes the problem is too complicated to be efficiently solved by a human. Sometimes Pascal is just lacking the speed. In such cases, we can try finding an existing library that solves our problem. In most cases, it will not support Delphi directly but will provide some kind of C or C++ interface. This chapter looks into linking with C object files and describes typical problems that you'll encounter on the way. In the second half, I'll present a complete example of linking to a C++ library, from writing a proxy DLL to using it in Delphi.

Chapter 9, Best Practices, wraps it all up. In this last chapter, I'll revisit all the important topics I explored in previous chapters. At the same time, I'll drop in some additional tips, tricks, and techniques.

To get the most out of this book

Although you can read this book in bed or on the beach, you will need a computer and Delphi to play with the code examples. The code was written in Delphi 10.2 Tokyo, but it should also work without a problem in the older versions. I did use some modern features in demos—and dedicated a chapter to Parallel Programming Library that was introduced in Delphi XE7—so anything older than that is hit and miss.

This book does not refer to any functionality specific to the Enterprise edition. You'll be able to test all the code with the entry-level professional edition.

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Глава 1. О производительности

"My program is not fast enough. Users are saying that it is not performing well. What can I do?"

«Моя программа недостаточно быстра. Пользователи говорят, что она выполняется не очень хорошо. Что я могу сделать?»

These are the words I hear a lot when consulting on different programming projects. Sometimes the answer is simple, sometimes hard, but almost always the critical part of the answer lies in the question. More specifically, in one word - performing.

Эти слова я часто слышу, консультируя по различным проектам программирования. Иногда ответ прост, иногда труден, но почти всегда решающая часть ответа заключается в вопросе. Точнее, одним словом — выполнение.

What do we mean when we say that a program is performing well? Actually, nobody cares. What we have to know is what users mean when they say that the program is not performing well. And users, you'll probably admit, look at the world in a very different way than we programmers.

Что мы имеем в виду, когда говорим, что