How to implement backtrace in golang

In the software development process, sometimes we need debug programs to find problems. A commonly used method is to obtain the function call stack through backtrace, which is very helpful for finding problems. This article will introduce how to implement backtrace through golang language.

1. The concept of backtrace

The Chinese translation of backtrace is "backtrace". Backtrace means that when an error occurs in the program, it prints out the function call stack to help us find the location of the problem. In C language, we can get the function call stack through the backtrace function. It is similar in golang language. We can print backtrace through the function in the runtime package.

2. Backtrace in golang

In golang, the call stack of the return program can be implemented through the functions in the runtime package. We can use the runtime.Callers function to obtain call stack information. It is defined as follows:

func Callers(skip int, pc []uintptr) int

where skip represents the number of stack frames to be skipped, and pc is a slice of uintptr type, representing a function pointer in the call stack. Callers returns the number of pointers obtained, or 0 if the number of skipped frames is greater than the length of the call stack.

The following is a simple usage example:

package main

import (
    "fmt"
    "runtime"
)

func printStack() {
    // 获取调用栈信息
    pcs := make([]uintptr, 10)
    n := runtime.Callers(0, pcs)

    // 翻译函数指针为函数名
    for i := 0; i < n; i++ {
        funcName := runtime.FuncForPC(pcs[i]).Name()
        fmt.Printf("#%d %s\n", i, funcName)
    }
}

func func1() {
    printStack()
}

func func2() {
    func1()
}

func main() {
    func2()
}

The running results are as follows:

#0 main.func1
#1 main.func2
#2 main.main

As you can see, we successfully printed out the function call stack information.

3. Practical application of backtrace

By implementing backtrace in golang, we can conveniently print out the function call stack information when a problem occurs in the program, helping us locate the problem. location to resolve issues more quickly. The following is a simple usage example:

package main

import (
    "fmt"
    "runtime"
)

func func1() {
    printStack()
}

func func2() {
    func1()
}

func main() {
    defer func() {
        if err := recover(); err != nil {
            // 发生panic时，打印函数调用栈信息
            printStack()
        }
    }()

    // 模拟发生程序异常
    var x *int
    *x = 0

    func2()
}

func printStack() {
    fmt.Println("**********************************")
    // 获取调用栈信息
    pcs := make([]uintptr, 10)
    n := runtime.Callers(0, pcs)

    // 翻译函数指针为函数名，并打印
    for i := 0; i < n; i++ {
        funcName := runtime.FuncForPC(pcs[i]).Name()
        file, line := runtime.FuncForPC(pcs[i]).FileLine(pcs[i])
        fmt.Printf("#%d %s %s:%d\n", i, funcName, file, line)
    }
    fmt.Println("**********************************")
}

In the above example, we simulated an exception in the program and printed out the function call stack information in the defer function. The running results are as follows:

**********************************
#0 main.func1 /path/to/main.go:10
#1 main.func2 /path/to/main.go:14
#2 main.main /path/to/main.go:22
**********************************
**********************************
#0 main.printStack /path/to/main.go:25
#1 main.main /path/to/main.go:20
**********************************

As you can see from the output results, when an exception occurs in the program, we print out the function call stack information, which can easily locate the code location where the problem is located.

4. Summary

Through the functions in the runtime package, we can easily implement the backtrace function in the golang language. Printing function call stack information through backtrace can easily locate problems in the program, thus speeding up the problem solving process.

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