How to deal with concurrent file reading and writing in Go language?

How to deal with concurrent file reading and writing in Go language?

During the development process, we often encounter situations where we need to read and write files. In a concurrent environment, file reading and writing issues need to be handled carefully to ensure data consistency and thread safety. This article will introduce how to handle concurrent file reading and writing in the Go language and provide specific code examples.

1. Using Mutex (Mutex)

Mutex is one of the most commonly used thread synchronization mechanisms, which ensures that only one thread can access shared resources at the same time. In the Go language, you can use Mutex in the sync package to implement a mutex lock.

The following is a sample code that shows how to use a mutex lock to perform file read and write operations in a concurrent environment:

package main

import (
    "fmt"
    "io/ioutil"
    "os"
    "sync"
)

var mutex sync.Mutex

func readFile(filename string) {
    mutex.Lock()
    defer mutex.Unlock()

    file, err := os.Open(filename)
    if err != nil {
        fmt.Println("Error opening file:", err)
        return
    }
    defer file.Close()

    content, err := ioutil.ReadAll(file)
    if err != nil {
        fmt.Println("Error reading file:", err)
        return
    }

    fmt.Println("File content:", string(content))
}

func writeFile(filename string, content []byte) {
    mutex.Lock()
    defer mutex.Unlock()

    file, err := os.Create(filename)
    if err != nil {
        fmt.Println("Error creating file:", err)
        return
    }
    defer file.Close()

    _, err = file.Write(content)
    if err != nil {
        fmt.Println("Error writing file:", err)
        return
    }

    fmt.Println("File write completed.")
}

func main() {
    filename := "test.txt"
    content := []byte("Hello, Go!")

    go readFile(filename)
    go writeFile(filename, content)

    // 等待两个goroutine执行完毕
    time.Sleep(time.Second)
}

In the above code, we use the mutex lock mutex to protect the pair File read and write operations. Before reading and writing the file, we use mutex.Lock() to acquire the lock, and use mutex.Unlock() to release the lock after the operation is completed. This ensures that only one goroutine can read and write files at the same time.

2. Use read-write lock (RWMutex)

Read-write lock is a more efficient locking mechanism, with better performance in scenarios of more reading and less writing. In Go language, you can also use RWMutex in the sync package to implement read-write locks.

The following is a sample code that shows how to use read-write locks to perform file read and write operations in a concurrent environment:

package main

import (
    "fmt"
    "io/ioutil"
    "os"
    "sync"
)

var rwMutex sync.RWMutex

func readFile(filename string) {
    rwMutex.RLock()
    defer rwMutex.RUnlock()

    file, err := os.Open(filename)
    if err != nil {
        fmt.Println("Error opening file:", err)
        return
    }
    defer file.Close()

    content, err := ioutil.ReadAll(file)
    if err != nil {
        fmt.Println("Error reading file:", err)
        return
    }

    fmt.Println("File content:", string(content))
}

func writeFile(filename string, content []byte) {
    rwMutex.Lock()
    defer rwMutex.Unlock()

    file, err := os.Create(filename)
    if err != nil {
        fmt.Println("Error creating file:", err)
        return
    }
    defer file.Close()

    _, err = file.Write(content)
    if err != nil {
        fmt.Println("Error writing file:", err)
        return
    }

    fmt.Println("File write completed.")
}

func main() {
    filename := "test.txt"
    content := []byte("Hello, Go!")

    go readFile(filename)
    go writeFile(filename, content)

    // 等待两个goroutine执行完毕
    time.Sleep(time.Second)
}

In the above code, we use the read-write lock rwMutex to protect the pair File read and write operations. When reading a file, we use rwMutex.RLock() to obtain a read lock, which allows multiple goroutines to perform read operations at the same time. When writing a file, we use rwMutex.Lock() to obtain the write lock to ensure that only one goroutine performs writing operations at the same time. After the operation is completed, the corresponding RLock() and Lock() must be used to release the lock.

By using mutex locks and read-write locks, concurrent file reading and writing issues can be effectively handled and data consistency and thread safety ensured. Whether you use a mutex lock or a read-write lock, you need to choose an appropriate lock mechanism based on the actual situation.

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