01_log_witer.go

package main

import (
	"fmt"
	"os"
	"sync"
)



func writeLog(filename, message string, wg *sync.WaitGroup) error {
	defer wg.Done()

	mu.Lock()
	defer mu.Unlock()

	file, err := os.OpenFile(filename, os.O_CREATE | os.O_WRONLY | os.O_APPEND, 0644)
	if err != nil {
		return err
	}
	defer file.Close()

	_, err = file.WriteString(message + "\n")
	if err != nil {
		return err
	}

	return nil
}

func logWriter() {
	var wg sync.WaitGroup
	filename := "log.txt"

	for i := 0; i < 5; i++ {
		wg.Add(1)
		message := fmt.Sprintf("Log entry %d", i + 1)
		go writeLog(filename, message, &wg)
	}

	wg.Wait()
	fmt.Println("All log entries written.")
}