System Programming Essentials with Go: System calls, networking, efficiency, and security practices with practical projects in Golang

System Programming Essentials with Go

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For Erika, my life partner, who supported me through the long hours and extra effort needed to complete this work. Your love and encouragement have been my constant source of strength.

Contributors

About the author

Alex Rios is an established Brazilian software engineer with a 15-year track record of success in large-scale solution development. He specializes in Go and creates high-throughput systems that address diverse needs across fintech, telecom, and gaming industries. As a staff engineer at Stone Co., Alex applies his expertise using unconventional system designs, ensuring top-notch delivery. Also, he uses his expertise to evaluate books and publications as a technical reviewer. He is an enthusiastic community member, actively participating in its growth and development as Curitiba’s Go meetup organizer. His dedication is evident in his regular presence as a speaker at major national tech events, such as GopherCon Brazil.

I would like to express my gratitude to Elton Minetto for opening this door and making the push for me to write my very first book. I am also immensely grateful to my editor, Kinnari Chohan, for her patience and meticulous attention to detail during the editing process. Your expertise and dedication have greatly enhanced the quality of this book. Lastly, a heartfelt thanks to the Go community for creating such an inspiring and supportive environment.

About the reviewer

Natan Streppel has over a decade of experience in the IT field and, in this period, has worked with a range of different technologies. He discovered Golang in 2017 and immediately fell for the language’s simplicity and expressiveness. Since then, he has been using the language and its ecosystem for both professional and non-professional projects. He thrives on tackling challenging problems in distributed systems, loves contributing to the open-source community, and enjoys exploring innovative solutions.

Table of Contents

Preface

Part 1: Introduction

1

Why Go?

Choosing Go

Concurrency and goroutines

Concurrency

Goroutines

CSP-inspired model

Share by communication

Interacting with the OS

Tooling

go build

go test

go run

go vet

go fmt

Cross-platform development with Go

Summary

2

Refreshing Concurrency and Parallelism

Technical requirements

Understanding goroutines

WaitGroup

Changing shared state

Managing data races

Atomic operations

Mutexes

Making sense of channels

How to use channels

An unbuffered channel

Buffered channels

The guarantee of delivery

Latency

State and signaling

State

Signaling

Choosing your synchronization mechanism

Summary

Part 2: Interaction with the OS

3

Understanding System Calls

Technical requirements

Introduction to system calls

The catalog of services and identification

Information exchange

The syscall package

A closer look at the os and x/sys packages

x/sys package – low-level system calls

Operating system functionality

Portability

Everyday system calls

Tracing system calls

Tracing specific system calls

Developing and testing a CLI program

Standard streams

File descriptors

Creating a CLI application

Redirections and standard streams

Making it testable

Summary

4

File and Directory Operations

Technical requirements

Identifying unsafe file and directory permissions

Files and permissions

Scanning directories in Go

Understanding file paths

Using the path/filepath package

Traversing directories

Symbolic links and unlinking files

Symbolic links – the shortcut of the file world

Unlinking files – the great escape act

Calculating directory size

Finding duplicate files

Optimizing filesystem operations

Summary

5

Working with System Events

Managing system events

What are signals?

The os/signal package

Task scheduling in Go

Why schedule?

Basic scheduling

Handling timer signals

File monitoring

Inotify

fsnotify

File rotation

Process management

Execution and timeouts

Execute and control process execution time

Building a distributed lock manager in Go

Summary

6

Understanding Pipes in Inter-Process Communication

Technical requirements

What are pipes in IPC?

Why are pipes important?

Pipes in Golang

The mechanics of anonymous pipes

Navigating named pipes (Mkfifo())

Best practices – guidelines for using pipes

Efficient data handling

Error handling and resource management

Security considerations

Performance optimization

Developing a log processing tool

Summary

7

Unix Sockets

Introduction to Unix sockets

Creating a Unix socket

Going a little deeper into socket creation

Creating the client

Inspecting the socket with lsof

Building a chat server

The complete chat client

Serving HTTP under UNIX domain sockets

Client

HTTP request line

HTTP request header

Empty line signifying end of headers

The textproto package

Performance

Other common use cases

Summary

Part 3: Performance

8

Memory Management

Technical requirements

Garbage collection

Stack and heap allocation

The GC algorithm

GOGC

GC pacer

GODEBUG

Memory ballast

GOMEMLIMIT

Memory arenas

Using memory arenas

Summary

9

Analyzing Performance

Escape analysis

Stack and pointers

Pointers

Stack

Heap

How can we analyze?

Benchmarking your code

Writing your first benchmark

Memory allocations

Common pitfalls

CPU profiling

Memory profiling

Profiling memory over time

Preparing to explore the trade-offs

Summary

Part 4: Connected Apps

10

Networking

The net package

TCP sockets

HTTP servers and clients

HTTP verbs

HTTP status codes

Putting it all together

Securing the connection

Certificates

Advanced networking

UDP versus TCP

Summary

11

Telemetry

Technical requirements

Logs

Zap versus slog

Logging for debugging or monitoring?

What to log?

What not to log?

Traces

Effective tracing

Distributed tracing

Metrics

What metric should we use?

The OTel project

OTel

Summary

12

Distributing Your Apps

Technical requirements

Go Modules

The routine using modules

CI

Caching

Static analysis

Releasing your application

Summary

Part 5: Going Beyond

13

Capstone Project – Distributed Cache

Technical requirements

Understanding distributed caching

System requirements

Requirements

Design and trade-offs

Creating the project

Thread safety

Choosing the right approach

Adding thread safety

The interface

TCP

HTTP

Others

Eviction policies

Sharding

Summary

14

Effective Coding Practices

Technical requirements

Reusing resources

Using sync.Pool in a network server

Using sync.Pool for JSON marshaling

Executing tasks once

singleflight

Effective memory mapping

API usage

Advanced usage with protection and mapping flags

Avoiding common performance pitfalls

Leaking with time.After

Defer in for loops

Maps management

Resource management

Handling HTTP bodies

Channel mismanagement

Summary

15

Stay Sharp with System Programming

Real-world applications

Dropbox’s leap of faith

HashiCorp – Go from day one

Grafana Labs – visualizing success with Go

Docker – building a container revolution with Go

SoundCloud – from Ruby to Go

Navigating the system programming landscape

Go release notes and blog

Community

Contribution

Experimentation

Resources for continued learning

Advanced Programming in the UNIX Environment by W. Richard Stevens

Learn C Programming - Second Edition: A beginner’s guide to learning the most powerful and general-purpose programming language with ease

Linux Kernel Programming - Second Edition: A comprehensive and practical guide to kernel internals, writing modules, and kernel synchronization

Linux System Programming Techniques: Become a proficient Linux system programmer using expert recipes and techniques

Operating Systems: Design and Implementation by Andrew S. Tanenbaum

Unix Network Programming by W. Richard Stevens

Linux System Programming Techniques: Become a proficient Linux system programmer using expert recipes and techniques

Mastering Embedded Linux Programming - Third Edition: Create fast and reliable embedded solutions with Linux 5.4 and the Yocto Project 3.1 (Dunfell)

Modern Operating Systems by Andrew S. Tanenbaum

The Art of UNIX Programming by Eric S. Raymond

Your system programming journey

Appendix

Hardware Automation

Automation in system programming

USB

Application

The goal

The /proc/mounts file

Reading the files on the flash drive

Partitions versus blocks versus devices versus disks

Open source to the rescue!

Interacting with USB events

Bluetooth

Detecting the smartwatch

Locking the screen

XDG dilemma

The Wayland conundrum

Summary

Index

Other Books You May Enjoy

Preface

System programming is a critical area of knowledge in software engineering. It matters most for professionals who want to write efficient, low-level code that interacts closely with the operating system. System Programming Essentials with Go is designed to guide you through the principles and practices necessary to stand up in system programming using Go. This book covers a broad range of topics, from basic system programming concepts to advanced techniques, providing a comprehensive toolkit for tackling real-world system programming challenges.

Who this book is for

This book is tailored for software engineers, architects, and developers who possess a basic understanding of programming and seek to deepen their knowledge of system design. It is ideal for those addressing complex design problems at work or simply interested in enhancing their skills with low-level programming in general. A foundational understanding of programming concepts and experience with at least one programming language is required.

What this book covers

Chapter 1

, Why Go?, provides an overview of Go’s suitability for building efficient and high-performance system software, providing you with the necessary knowledge and skills to leverage Go’s capabilities for system-level development. The chapter covers Go’s concurrency model, networking and I/O, low-level control, system calls, cross-platform support, and tooling, offering practical insights and examples for building robust system programs.

Chapter 2

, Refreshing Concurrency and Parallelism, provides an overview of the core aspects of Goroutines, data races, channels, and their interplay in the Go programming language. Understanding these principles is critical for implementing efficient concurrency, managing shared resources, and ensuring effective inter-goroutine communication.

Chapter 3

, Understanding System Calls, provides an overview of system calls and their practical applications. You will learn how to create symbolic links, unlink files, and manipulate filename paths. Also, you will better understand package OS and syscall in Go and learn how to develop and test a CLI program.

Chapter 4

, File and Directory Operations, provides an overview of handling filesystems in Go, focusing on detecting unsafe permissions, calculating directory sizes, and identifying duplicate files.

Chapter 5

, Working with System Events, provides comprehensive insights into building advanced and efficient system tools using Go, focusing on task scheduling, file monitoring, process management, and distributed locking.

Chapter 6

, Understanding Pipes in Inter-Process Communication, provides an exploration of the concept of pipes in Inter-Process Communication (IPC). It provides comprehensive information about anonymous pipes, named pipes (mkfifo), and how pipes interact with other programs.

Chapter 7

, Unix Sockets, provides an understanding of how UNIX sockets function, their types, and their role in IPC on UNIX and UNIX-like operating systems such as Linux.

Chapter 8

, Memory Management, focuses on the mechanisms and strategies underpinning garbage collection. We’ll explore the evolution of Go’s garbage collection, the distinctions between stack and heap memory allocations, and advanced techniques for efficient memory management.

Chapter 9

, Analyzing Performance, covers key optimization techniques for Go applications, including escape analysis, benchmarking, CPU profiling, and memory profiling. It explains how to improve memory usage with escape analysis, measure and compare code performance through benchmarking, identify hotspots with CPU profiling, and detect memory leaks using memory profiling.

Chapter 10

, Networking, delves into the fascinating world of Go network programming. Networking is essential to system programming, and Go provides powerful primitives for handling network communications. You will gain the expertise needed to create robust networked applications by exploring TCP, HTTP, and additional relevant protocols.

Chapter 11

, Telemetry, dives into how you can leverage industry tools to implement effective telemetry practices. From logs to traces and metrics, you’ll explore the tools and guidelines necessary to monitor your application efficiently.

Chapter 12

, Distributing Your Apps, explores the key concepts and practical applications of distributing applications using Go modules, continuous integration, and release strategies.

Chapter 13

, Capstone Project - Distributed Cache, guides you through the Capstone Project. This project will build a distributed cache system in Go with features such as Memcached or Redis. It will cover sharding strategies, eviction policies, consistency models, and technology choices, all while navigating the trade-offs that come with each decision.

Chapter 14

, Effective Coding Practices, explores the principles and techniques of efficient resource management in Go programming, specifically focusing on avoiding common pitfalls that can lead to performance issues and hinder overall efficiency. It dives into the intricacies of optimizing resource usage using the Go standard library, providing strategies for developers seeking to enhance the effectiveness of their Go applications.

Chapter 15

, Stay Sharp with System Programming, provides a continuous learning path to Go-based system programming based on real-world case studies. By gaining insight into how Go is utilized in actual applications, you can apply these lessons to their projects.

Appendix, Hardware Automation, explores how to utilize various tools to automate mundane tasks with USB drives and Bluetooth devices and monitor peripheral events. By understanding how to automate these processes, you will save valuable time and increase productivity in your daily lives.

To get the most out of this book

You will need to have an understanding of the basics of Golang.

If you are using the digital version of this book, we advise you to type the code yourself or access the code from the book’s GitHub repository (a link is available in the next section). Doing so will help you avoid any potential errors related to the copying and pasting of code.

Download the example code files

You can download the example code files for this book from GitHub at https://github.com/PacktPublishing/System-Programming-Essentials-with-Go

. If there’s an update to the code, it will be updated in the GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/

. Check them out!

Conventions used

There are a number of text conventions used throughout this book.

Code in text: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: Lastly, update the main function to create a cache with a specified capacity and test the TTL and LRU features.

A block of code is set as follows:

func main() {

    cache := NewCache(5) // Setting capacity to 5 for LRU

    cache.startEvictionTicker(1 * time.Minute)

}

Any command-line input or output is written as follows:

go run main.go -port=:8080 -peers=http://localhost:8081

Tips or important notes

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Part 1: Introduction

In this part, we will explore the foundational aspects of using Go for system programming. You will learn about the best practices in managing concurrency, and ensuring efficient cross-platform development. This section provides a closer look at why Go is a powerful choice for building high-performance system software and how to leverage its features to support real-world scenarios.

This part has the following chapters:

Chapter 1

, Why Go?

Chapter 2

, Refreshing Concurrency and Parallelism

1

Why Go?

At some point in your programming journey, your programs performed I/O-related tasks such as creating and removing files and directories. They may have orchestrated the creation of new processes and the execution of other programs or even facilitated communication between threads and processes on the same computer and between processes on different computers connected via a network.

When our programs center on using a low-level set of tasks, we categorize them as system programming.

It is alleged that system programming is tedious. But I do not see it this way at all! In fact, it is quite the opposite – an enjoyable and entertaining experience. It is like being a magician. You get to control the operating system and hardware, and you can make things happen that would be impossible in other languages.

In this chapter, we discuss why Go is an excellent fit for building efficient, high-performance system software to support real-world scenarios.

In this chapter, we are going to cover the following main topics:

Choosing Go

Concurrency and goroutines

Interacting with the OS

Tooling

Cross-platform development with Go

By the end of this chapter, you will have a grasp of where Go is in the ecosystem of system programming, the importance of the Go concurrency model to build efficient and high-performance system software, how Go chooses to interact with the OS, the Go approach to cross-platform development, and the main commands in the Go built-in tooling.

Choosing Go

There are plenty of languages in the system programming space nowadays: some are well established, such as C and C++; some form a wave of newcomers, such as Zig, Rust, and Odin; and others claim the title of C/C++ killer, with their pledges of impressive performance.

Sure, we can use all of them and achieve outstanding results. Still, we could fall into hidden traps such as a steep learning curve, high cognitive load, a lack of community and support, inconsistent APIs with constant breaking changes, and a lack of adoption.

Go’s design philosophy emphasizes simplicity, expressiveness, robustness, and efficiency. Its support for concurrency and strong dependency management, as well as its focus on composition, make it a compelling choice for system programming. Its creators aimed to build a language that provides powerful building blocks without unnecessary complexity, which makes writing, reading, understanding, and maintaining system-level code easier. People with programming experience usually take two weeks to get acquainted with Go. While they may not be considered experts, they can confidently read standard Go code and write basic to medium-complexity programs without struggle.

Also, Go is excellent for system programming because the language has a Unix-minded design by checking all the boxes for simplicity. Many programmers who are proficient in Python and Ruby often transition to Go, as it allows them to retain their level of expressiveness while achieving improved performance and the capability to work with concurrency.

It is worth noting that Go’s philosophy doesn’t prioritize zero cost in terms of CPU usage. Instead, the language aims to reduce the effort demanded from programmers, which is considered more significant and, as a by-product, makes the experience enjoyable.

One of the leading criticisms of using Go for system programming is the garbage collector (GC), specifically its pauses and explicit memory limits. If you still have this pet peeve with Go, don’t worry. In Chapter 6

, we’ll see that more granular memory management is available from Go 1.20 and above.

Note

In a GC pause worst-case scenario, the stop-the-world time is typically less than 100 microseconds.

Concurrency and goroutines

One of the most essential features of Go is its concurrency model. Concurrency is the ability to run multiple tasks at the same time. In system programming, executing many tasks in parallel is essential for improving the performance and responsiveness of our programs.

Concurrency

Real-time systems demand precision, with concurrency being a pivotal factor. These systems coordinate tasks with exceptional timing, particularly in scenarios where even milliseconds matter. Concurrency offers significant advantages by increasing throughput (a measure of how many units of information a system can process in a given amount of time) while decreasing task completion times. Real-life instances show how concurrency improves responsiveness, making systems more flexible and tasks more efficient. Moreover, concurrency’s isolation abilities guarantee data integrity by preventing interference.

System programming involves a diverse range of tasks, from CPU-bound to I/O-bound. Concurrency orchestrates this diversity by allowing CPU-bound tasks to progress while I/O-bound tasks await resources.

Later, in Chapter 10

, when we discuss distributed systems, the importance of concurrency will shine. It orchestrates tasks across an application or even different nodes in the network, which is ideal for managing large-scale concurrency.

Goroutines

Go’s concurrency model relies on goroutines and channels. Goroutines are lightweight execution threads, often referred to as green threads. Creating them is cost-effective. Unlike conventional threads, they exhibit remarkable efficiency, enabling thousands of goroutines to run simultaneously on just a few OS threads.

Channels, on the other hand, provide a mechanism for goroutines to communicate and synchronize without resorting to locks. This approach is inspired by the Communicating Sequential Process (CSP) (https://www.cs.cmu.edu/~crary/819-f09/Hoare78.pdf

) formalism, emphasizing coordinated interactions between concurrent components.

Diverging from numerous other programming languages that depend on external libraries or threading constructs for concurrency, Go incorporates concurrency seamlessly into its core language design. This design decision leads to code that is not only easier to comprehend but also less susceptible to errors, as the complexities of threading are abstracted.

CSP-inspired model

Go’s concurrency model draws inspiration from CSP, a formal language for describing concurrent systems. CSP focuses on communication and synchronization between concurrently executing entities. Unlike traditional multi-threaded programming, CSP and Go prioritize communication through channels instead of shared memory, reducing complexity and potential hazards. Synchronization and coordination are essential, with CSP using channels for process synchronization and Go using similar channels to coordinate goroutines. Safety and isolation are key, as both languages ensure safe interaction through channels, enhancing predictability and reliability. Go’s channels directly realize CSP’s communication-based approach, providing a safe way for goroutines to exchange data without the pitfalls of shared memory and locks.

Share by communication

The famous Go proverb, Don’t communicate by sharing memory, share memory by communicating is often a source of discussion and misinterpretation. Still, reading it as Share by communicating, not by locking would be more precise, mainly because mainstream languages often rely on locks to protect shared data, leading to potential issues such as deadlocks and race conditions. Go encourages a different paradigm: sharing data through channels by sending and receiving messages. This share by communicating philosophy reduces the need for explicit locks and promotes a safer concurrency environment.

If you are into functional programming, I have great news for you. In Go, data is not implicitly shared between goroutines. In other words, the data is copied. Did you see the concern with data immutability? This stands in contrast to languages, where shared memory is the default mode of communication between threads. Go’s emphasis on explicit communication via channels helps avoid the unintended data sharing and race conditions that can arise in traditional threading models. Another benefit of this model is that there is no callback hell since every interaction with concurrent code is often read in a procedural manner. A regular Go function can be used in procedural code without tying the signatures with extra keywords.

Note

Callback hell, also known as the pyramid of doom, is a term used in programming to describe a situation where nested and interdependent callback functions make the code difficult to read, understand, and maintain. This typically occurs in asynchronous programming environments, such as JavaScript, where callbacks are used to handle asynchronous operations.

In the next chapter, we will refresh all concepts of concurrency and its building blocks to prepare you for interacting with the OS interfaces.

In addition to its concurrency model, Go also provides a way to interact with the operating system at a low level. This is essential for system programming, where you often need to control the OS and hardware.

Interacting with the OS

Go’s approach to system calls is designed to be safe and efficient, especially in the context of its concurrency model.

In Go, system calls are comparatively lower-level in comparison to certain other programming languages. It can be helpful if you need fine-grained control over system resources, but it also means you’re dealing with more low-level details.

Making system calls often requires understanding the underlying operating system APIs and conventions. The side effect is that it can introduce a steeper learning curve if you are new to systems programming or lower-level development.

Not familiar with system calls? Fear not! The book’s second part will explore and experiment with them in detail to cover the main aspects we need to progress in our system programming journey.

Tooling

Go is like a toolbox. It has everything we need to build great software, so we don’t need anything more than its standard tools to create our programs.

Let’s explore the principal tools that facilitate building, testing, running, error-checking, and code formatting.

go build

The go build command is used to compile Go code into an executable binary that you can run.

Let’s see an example.

Assume you have a Go source file named main.go containing the following code:

package main

import fmt

func main() {

    fmt.Println(Hello, Go!)

}

You can compile it using the go build command:

go build main.go

This will generate an executable binary named main (or main.exe on Windows). You can then run the binary to see the output:

./main

go test

The go test command is used to run tests on your Go code. It automatically finds test files and runs the associated test functions.

Here’s an example.

Assume you have a Go source file named math.go containing a function to add two numbers:

package math

func Add(a, b int) int {

    return a + b

}

You can create a test file named math_test.go to write tests for the Add function:

package math

import testing

func TestAdd(t *testing.T) {

    result := Add(2, 3)

    if result != 5 {

        t.Errorf(Expected 5, but got %d, result)

    }

}

Run the tests using the go test command:

go test

go run

The go run command allows you to run Go code directly without explicitly compiling it into an executable.

Let’s see this using an example.

Assume you have a Go source file named hello.go containing the following code:

package main

import fmt

func main() {

    fmt.Println(Hello, Go!)

}

You can directly run the code using the go run command:

go run hello.go

This will execute the code and print Hello, Go! to the console.

go vet

We use the go vet command to check our Go code for potential errors or suspicious constructs. It employs heuristics that may not ensure all reports are actual issues, but it can uncover errors not caught by the compilers.

Here’s an example.

Assume you have a Go source file named error.go containing the following code with an intentional error:

package main

import fmt

func main() {

    movie_year := 1999

    movie_title := The Matrix

    fmt.Printf(In %s, %s was released.\n, movie_year, movie_title)

}

You can use the go vet command to check for errors:

go vet error.go

It might report a warning such as this: Printf format %s has arg 1999 of wrong type int.

go fmt

The go fmt command is used to format your Go code according to the Go programming style guidelines. It automatically adjusts code indentation, spacing, and more.

Let’s see an example for this too.

Assume you have a Go source file named unformatted.go containing improperly formatted code:

package main

import fmt

func main() {

        msg:=Hello

        fmt.Println(msg)

}

You can format the code using the go fmt command:

go fmt unformatted.go

It will update the code to match the standard formatting conventions:

package main

import fmt

func main() {

        msg := Hello

        fmt.Println(msg)

}

Now that we have a good grasp of the basic tools, we can start familiarizing ourselves with Go’s cross-platform capabilities.

Cross-platform development with Go

Cross-platform development with Go is a breeze. You can write code running on various operating systems and architectures with ease.

Cross-platform development with Go can be achieved by using the GOOS and GOARCH environment variables. The GOOS environment variable specifies the OS you want to target, and the GOARCH environment variable specifies your target architecture.

For example, assume you have a Go source file named main.go:

package main

import fmt

func main() {

    fmt.Println(This program runs in any OS!)

}

To compile code for