Book Image

Hands-On Design Patterns with Delphi

By : Primož Gabrijelčič
Book Image

Hands-On Design Patterns with Delphi

By: Primož Gabrijelčič

Overview of this book

Design patterns have proven to be the go-to solution for many common programming scenarios. This book focuses on design patterns applied to the Delphi language. The book will provide you with insights into the language and its capabilities of a runtime library. You'll start by exploring a variety of design patterns and understanding them through real-world examples. This will entail a short explanation of the concept of design patterns and the original set of the 'Gang of Four' patterns, which will help you in structuring your designs efficiently. Next, you'll cover the most important 'anti-patterns' (essentially bad software development practices) to aid you in steering clear of problems during programming. You'll then learn about the eight most important patterns for each creational, structural, and behavioral type. After this, you'll be introduced to the concept of 'concurrency' patterns, which are design patterns specifically related to multithreading and parallel computation. These will enable you to develop and improve an interface between items and harmonize shared memories within threads. Toward the concluding chapters, you'll explore design patterns specific to program design and other categories of patterns that do not fall under the 'design' umbrella. By the end of this book, you'll be able to address common design problems encountered while developing applications and feel confident while building scalable projects.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
About Packt

Thread pool

A thread pool pattern can be simply described as a collection of threads. Some of them may be doing useful work, while others are sitting idle, waiting for you to run any job in them. To the careful reader of this book, the thread pool pattern would seem like an old acquaintance. After all, it is nothing more than a variation on a object pool pattern, which was discussed in Chapter 2, Singleton, Dependency Injection, Lazy Initialization, and Object Pool.


A thread pool is like a taxi service. When you need to travel somewhere, you call the dispatch and as soon as they have a taxi ready, they will send it to pick you up.

Using a thread pool minimizes the time a background task needs to start up. Creating a thread can take some time (up to ten milliseconds and more on older hardware), which can be a problem in highly optimized, heavily multi-threaded programs, for example, in a server handling many concurrent clients. Starting a job in a thread from a thread pool (provided that...