The application of golang framework panic and recovery in debugging

Panic in the Go framework is used to raise unrecoverable exceptions, and Recover is used to recover from Panic and perform cleanup operations. They can handle exceptions such as database connection failures, ensuring application stability and user experience.

Use Go framework Panic and Recover in debugging

Panic and Recover are two key mechanisms for handling exceptions in the Go framework. During debugging, They can play a vital role.

Panic

Panic is a built-in method in Go used to raise exceptions. It will immediately terminate the currently running goroutine and print out the exception information. In general, panic should only be used when an unrecoverable error is encountered.

Usage scenarios:

• When the application encounters an internal error and cannot recover from the error.
• When the application encounters a violation of business logic or data inconsistency.

Syntax:

func(parameters) (result, parameters) {
    // 判断是否需要抛出异常
    if (condition) {
        panic(reason)
    }
    return result, parameters
}

Recover

Recover is used to recover from panic. It can obtain the exception information caused by panic and return to execution. process.

Usage scenarios:

• Catch panic in goroutine and perform necessary cleanup operations.
• Catch panics in web servers and display friendly error messages to users.

Syntax:

func(parameters) (result, parameters) {
    defer func() {
        if err := recover(); err != nil {
            // 处理 panic 异常
        }
    }()
    return result, parameters
}

Practical case

Consider a simple Go web server that uses panic to handle database connection failure errors:

package main

import (
    "database/sql"
    "fmt"
    "log"
    "net/http"
)

func main() {
    // 连接数据库
    db, err := sql.Open("mysql", "user:password@/database")
    if err != nil {
        // 数据库连接失败则抛出 panic
        panic(err)
    }

    // 启动 web 服务器
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        defer func() {
            if err := recover(); err != nil {
                // 捕获 panic 并在 Web 响应中显示错误消息
                w.WriteHeader(http.StatusInternalServerError)
                w.Write([]byte("Internal error occurred. Please try again later."))
                log.Printf("Panic occurred: %s", err)
            }
        }()

        // 访问数据库并执行查询
        rows, err := db.Query("SELECT * FROM users")
        if err != nil {
            // 数据库查询失败则抛出 panic
            panic(err)
        }

        // 处理查询结果
        // ...
    })

    log.Fatal(http.ListenAndServe(":8080", nil))
}

In the above example, the Open() function will connect to the database and return a sql.DB instance. If the connection fails, the Open() function will throw a panic. The main() function uses defer and recover() to catch panic.

When the web server processes a request, the Query() function queries the database and returns the query results. If the query fails, the Query() function will throw a panic. recover() The function will capture this panic and write the error message to the log.

By using panic and recover, applications can handle exceptions gracefully while providing users with friendly error messages. This is crucial to ensure application stability and improve user experience.

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