How to debug golang

As Golang continues to grow, it is becoming more and more popular among developers. However, even if you are an experienced Golang developer, you may encounter some errors in your code. At this time, debugging will be very useful. This article will introduce you to some basic knowledge and methods of debugging Golang programs.

Why do you need debugging?

In the process of program development, errors and exceptions are common. These errors and exceptions can be caused by things like errors in the code you write or errors in the underlying system. If you don't review and debug your code carefully as you write it, it can be difficult to figure out the cause of the error. Debugging is an essential part of helping you find problems and fix them faster.

Compile Flag

During the debugging process, you can use -gcflags to compile the code and generate corresponding debugging information. For example, the following command compiles the code into an executable file with debugging information:

go build -gcflags "-N -l" main.go

where -N means not to optimize the code and generate debugging information. -l means disallowing inline code. This way you can inspect more variables and lines of code at runtime and find errors more easily. Of course, adding debugging information during compilation may also affect runtime performance. Therefore, you need to consider the trade-off between performance and debugging information when releasing your product.

Printf() Debugging

Printf() is a simple and practical debugging method. It can output the status and variables of the program to help us locate problems. In Golang, using Printf() requires the fmt package. For example:

package main

import "fmt"

func main() {
    user := getUser()
    fmt.Printf("user: %v\n", user)
}

func getUser() string {
    return "user"
}

In this code, we use Printf() to output the value of the variable user. If the variable value changes during runtime, you can output more variable values ​​and add timestamps or other useful information when printing the log. When using Printf() for debugging, it should be noted that if you forget to delete some debugging code, this may affect the performance of the program and the debugging results.

GDB Debugging

GDB is a well-known debugger that supports Golang and other languages. GDB can help us perform a series of debugging operations while the program is running, such as breakpoints, variable monitoring, and call stack tracing. The following are some commonly used GDB commands:

• break <line number name></line> : Set a breakpoint at the specified line, file or function.
• run: Run the program.
• next : Step over the current line and enter the next line.
• step : Execute the current line and go to the next function call.
• print <variable></variable>: Output the value of the variable.
• backtrace : Display the call stack.
• continue : Continue running the program.
• quit : Exit GDB.

The following is an example of using GDB to debug a program:

package main

func main() {
    x := 1
    y := 2
    z := x + y
    println(z)
}

When compiling the code and debugging it using GDB, execute the following command:

go build -gcflags "-N -l" -o ./main main.go # 编译代码
gdb ./main # 启动GDB

In GDB, You can add breakpoints to your program and run the program using the run command to stop at the breakpoint. Use the print command to view the value of a variable and view the call stack to check function return values. By using GDB, you can analyze your code more deeply while your program is running to find the root cause of errors.

Delve Debugging

Delve is a new Golang debugger that uses Golang's runtime reflection API and supports functions such as breakpoints, call stack tracing, and variable monitoring. Before using Delve, you need to install it. Here is an example of using Delve to debug a program:

package main

import "fmt"

func main() {
    fmt.Println("Hello, Delve!")
    debugger()
}

func debugger() {
    x := 1
    y := 2
    z := x + y
    fmt.Printf("z = %d\n", z)
}

Compile and run the program using the following command:

go build -gcflags="-N -l" -o ./main main.go # 编译代码
dlv exec ./main # 启动 Delve

In Delve, you can use the following command:

• break <line number name></line> : Set a breakpoint at the specified line, file or function.
• run: Run the program.
• next : Step over the current line and enter the next line.
• step : Execute the current line and go to the next function call.
• print <variable></variable>: Output the value of the variable.
• backtrace : Display the call stack.
• continue : Continue running the program.
• exit : Exit Delve.

By using Delve, you can debug Golang programs quickly and easily to find out the cause of errors.

Summary

Debugging is an important step in writing high-quality code. In Golang, you can use a variety of methods to debug the program, such as adding a compilation flag, using the Printf() function, and using debuggers such as GDB and Delve. During the actual development process, you can choose which method to use based on your needs and habits. If you encounter problems while debugging, don't be discouraged, keep trying and understand your errors. By constantly debugging and modifying your code, you can create higher quality Golang programs.

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