Julia High Performance Second Edition

▶Book Description
Julia is a high-level, high-performance dynamic programming language for numerical computing. If you want to understand how to avoid bottlenecks and design your programs for the highest possible performance, then this book is for you.

The book starts with how Julia uses type information to achieve its performance goals, and how to use multiple dispatches to help the compiler emit high-performance machine code. After that, you will learn how to analyze Julia programs and identify issues with time and memory consumption. We teach you how to use Julia's typing facilities accurately to write high-performance code and describe how the Julia compiler uses type information to create fast machine code. Moving ahead, you'll master design constraints and learn how to use the power of the GPU in your Julia code and compile Julia code directly to the GPU. Then, you'll learn how tasks and asynchronous IO help you create responsive programs and how to use shared memory multithreading in Julia. Toward the end, you will get a flavor of Julia's distributed computing capabilities and how to run Julia programs on a large distributed cluster.

By the end of this book, you will have the ability to build large-scale, high-performance Julia applications, design systems with a focus on speed, and improve the performance of existing programs.

▶What You Will Learn
- Understand how Julia code is transformed into machine code
- Measure the time and memory taken by Julia programs
- Create fast machine code using Julia's type information
- Define and call functions without compromising Julia's performance
- Accelerate your code via the GPU
- Use tasks and asynchronous IO for responsive programs
- Run Julia programs on large distributed clusters

▶Key Features
- Learn the characteristics of high-performance Julia code
- Use the power of the GPU to write efficient numerical code
- Speed up your computation with the help of newly introduced shared memory multi-threading in Julia 1.0

▶Who This Book Is For
This book is for beginners and intermediate Julia programmers who are interested in high-performance technical programming. A basic knowledge of Julia programming is assumed.

▶What this book covers
- Chapter 1, Julia is Fast, is your introduction to Julia's unique performance. Julia is a highperformance language, with the possibility to run code that is competitive in performance with code written in C. This chapter explains why Julia code is fast. It also provides context and sets the stage for the rest of the book.

- Chapter 2, Analyzing Performance, shows you how to measure the speed of Julia programs and understand where the bottlenecks are. It also shows you how to measure the memory usage of Julia programs and the amount of time spent on garbage collection.

- Chapter 3, Types, Type Inference, and Stability, covers type information. One of the principal ways in which Julia achieves its performance goals is by using type information. This chapter describes how the Julia compiler uses type information to create fast machine code. It describes ways of writing Julia code to provide effective type information to the Julia compiler.

- Chapter 4, Making Fast Function Calls, explores functions. Functions are the primary artifacts for code organization in Julia, with multiple dispatch being the single most important design feature in the language. This chapter shows you how to use these facilities for fast code.

- Chapter 5, Fast Numbers, describes some internals of Julia's number types in relation to performance, and helps you understand the design decisions that were made to achieve that performance.

- Chapter 6, Using Arrays, focuses on arrays. Arrays are one of the most important data structures in scientific programming. This chapter shows you how to get the best performance out of your arrays—how to store them, and how to operate on them.

- Chapter 7, Accelerating Code with the GPU, covers the GPU. In recent years, the generalpurpose GPU has turned out to be one of the best ways of running fast parallel computations. Julia provides a unique method for compiling high-level code to the GPU. This chapter shows you how to use the GPU with Julia.

- Chapter 8, Concurrent Programming with Tasks, looks at concurrent programming. Most programs in Julia run on a single thread, on a single processor core. However, certain concurrent primitives make it possible to run parallel, or seemingly parallel, operations, without the full complexities of shared memory multi-threading. In this chapter, we discuss how the concepts of tasks and asynchronous IO help create responsive programs.

- Chapter 9, Threads, moves on to look at how Julia now has new experimental support for shared memory multi-threading. In this chapter, we discuss the implementation details of this mode, and see how this is different from other languages. We see how to speed up our computations using threads, and learn some of the limitations that currently exist in this model.

- Chapter 10, Distributed Computing with Julia, recognizes that there comes a time in every large computation's life when living on a single machine is not enough. There is either too much data to fit in the memory of a single machine, or computations need to be finished quicker than can be achieved on all the cores of a single processor. At that stage, computation moves from a single machine to many. Julia comes with advanced distributed computation facilities built in, which we describe in this chapter.