Mastering Debugging in Go with Delve

Table of Contents

  1. Introduction
  2. Prerequisites
  3. Setup
  4. Debugging Basics
  5. Breakpoints
  6. Examining Variables
  7. Stepping Through Code
  8. Conditional Breakpoints
  9. Restarting and Detaching

  10. Conclusion

Introduction

Welcome to the tutorial on mastering debugging in Go with Delve. Debugging is an essential skill for any developer, and Delve is a powerful debugger specifically built for the Go programming language. In this tutorial, you will learn how to effectively debug your Go code using Delve. By the end of this tutorial, you will be able to:

  • Set breakpoints and step through code
  • Examine variables and their values during runtime
  • Use conditional breakpoints to stop execution based on specific conditions
  • Restart or detach from a debugging session

Let’s get started!

Prerequisites

To follow along with this tutorial, you should have a basic understanding of the Go programming language and have Go installed on your machine. You should also have a code editor of your choice installed, such as Visual Studio Code or GoLand.

Setup

First, we need to install Delve. Open a terminal and execute the following command:

go get github.com/go-delve/delve/cmd/dlv

This will download and install Delve.

Debugging Basics

Before diving into the more advanced features of Delve, let’s cover some basic debugging concepts.

To start a debugging session, navigate to the directory containing your Go code in the terminal. Then, use the following command to launch Delve:

dlv debug

This will start the debugger and pause execution at the beginning of your main() function.

To resume execution, type c and press Enter.

Breakpoints

Breakpoints are markers that instruct the debugger to pause execution at a specific line of code. They are the most fundamental tool for debugging. You can set a breakpoint by adding break command followed by the line number or function name.

For example, to set a breakpoint at line 10 of your code, use the following command:

break main.go:10

To see all the breakpoints set in your code, use the breakpoints command.

breakpoints

To remove a breakpoint, use the clear command followed by the breakpoint ID. You can get the breakpoint ID from the list of breakpoints.

clear 1

Examining Variables

During debugging, it is crucial to examine the values of variables at specific points in the code. Delve provides several commands to help you with this.

To examine the value of a specific variable, use the print command followed by the variable name.

print variableName

To print all the available local variables within the current scope, use the locals command.

locals

To print all available variables, including global ones, use the funcs command.

funcs

Stepping Through Code

Stepping through code allows you to execute your code line by line, which is especially helpful in complex situations. Delve provides three main stepping commands:

  • Step into: s - This command executes the current line and stops at the next line. If the current line contains a function call, it will step into that function.
  • Step over: n - This command executes the current line and stops at the next line. If the current line contains a function call, it will execute the entire function without stepping into it.
  • Step out: finish - This command executes the remaining lines of the current function and stops at the line that called the current function.

Conditional Breakpoints

Delve allows you to set breakpoints that only trigger when certain conditions are met. This can be helpful when you want to stop execution only in specific scenarios.

To set a conditional breakpoint, use the break command followed by the line number or function name, and a condition enclosed in curly braces {}.

break main.go:10 {condition}

For example, to break only when i is equal to 5, use the following command:

break main.go:10 {i == 5}

Restarting and Detaching

Sometimes, you may want to restart or detach from a debugging session. Delve provides commands to assist with these actions.

To restart the program, use the restart command.

restart

To detach from the debugging session without terminating the program, use the detach command.

detach

Conclusion

Congratulations! You have now mastered debugging in Go with Delve. You have learned how to set breakpoints, examine variables, step through code, use conditional breakpoints, and restart or detach from a debugging session. These skills will greatly aid your ability to identify and fix issues in your Go code.

Remember, debugging is an iterative process, and practice is key to becoming proficient. Keep exploring Delve’s documentation and experimenting with different debugging scenarios to further enhance your debugging skills. Happy debugging!

Note: Delve provides many more features and commands that are not covered in this tutorial. For a comprehensive understanding, refer to the official Delve documentation.

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