Golang：使用log.Println登录文件是否照顾并发访问

Question

I have hundreds of subroutines writing into log file using log.Println()
I am using log.Println to write into error.log file.

func main() {
  e, err := os.OpenFile("error.log", os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
  if err != nil {
    fmt.Printf("error opening file: %v", err)
    os.Exit(1)
  }
  defer e.Close()
  errLog := log.New(e, ">>>", log.Ldate|log.Ltime)

  for i:=0; i<500; i++ {
      go worker(errLog)
  }
}

func worker(errLog log.Logger) {
  // Do some work 
  errLog.Println("Hello world!!!")
}

Is my approach correct ? Or should I use channel to make sure only one process is logging into file at one time or is it taken care of inherently by log package?

Also does log package takes care of buffering or it directly writes into file?

Answer 1

From log.go:

func (l *Logger) Output(calldepth int, s string) error {
   now := time.Now() // get this early.
   var file string
   var line int
   l.mu.Lock()
   defer l.mu.Unlock()
   // ... Rest omitted

Since pretty much all package log output functions go through Output, and there's a mutex in Output it's safe to say they're concurrency-safe.