Book Image

Julia High Performance

By : Avik Sengupta
Book Image

Julia High Performance

By: Avik Sengupta

Overview of this book

Julia is a high performance, high-level dynamic language designed to address the requirements of high-level numerical and scientific computing. Julia brings solutions to the complexities faced by developers while developing elegant and high performing code. Julia High Performance will take you on a journey to understand the performance characteristics of your Julia programs, and enables you to utilize the promise of near C levels of performance in Julia. You will learn to analyze and measure the performance of Julia code, understand how to avoid bottlenecks, and design your program for the highest possible performance. In this book, you will also see how Julia uses type information to achieve its performance goals, and how to use multuple dispatch to help the compiler to emit high performance machine code. Numbers and their arrays are obviously the key structures in scientific computing – you will see how Julia’s design makes them fast. The last chapter will give you a taste of Julia’s distributed computing capabilities.
Table of Contents (14 chapters)

How fast can Julia be?


The best evidence of Julia's performance claims is when you write your own code. However, we can provide an indication of how fast Julia can be by comparing a similar algorithm over multiple languages.

As an example, let's consider a very simple routine to calculate the power sum for a series, as follows:

The following code runs this computation in Julia 500 times:

function pisum()
    sum = 0.0
    for j = 1:500
        sum = 0.0
        for k = 1:10000
            sum += 1.0/(k*k)
        end
    end
    sum
end

You will notice that this code contains no type annotations. It should look quite familiar to any modern dynamic language. The same algorithm implemented in C would look something similar to this:

double pisum() {
    double sum = 0.0;
    for (int j=0; j<500; ++j) {
        sum = 0.0;
        for (int k=1; k<=10000; ++k) {
            sum += 1.0/(k*k);
        }
    }
    return sum;
}

Tip

Downloading the example code

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Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

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By timing this code, and its re-implementation in many other languages (all of which are available at https://github.com/JuliaLang/julia/tree/master/test/perf/micro), we can note that Julia's performance claims are certainly borne out in this limited test. Julia can perform at a level similar to C and other statically typed and compiled languages.

This is of course a micro benchmark, and should therefore not be extrapolated too much. However, I hope you will agree that it is possible to achieve excellent performance in Julia. The rest of the book will attempt to show how you can achieve performance close to this standard in your code.