[并发洗数go]

channel.go

var MAX_PARALLEL = 50
var sem = make(chan int, MAX_PARALLEL)
var f = "./ids.csv"

func bizFunc(id int64) {
    defer func(){<-sem}()
    // biz code.
}

func parallelWork() {
    file, err := os.Open(f)
    if err != nil {
       fmt.Println(err)
       return
    }
    defer file.Close()
    
    count := 0
    startTime := time.Now().Unix()
    scanner := bufio.NewScanner(file)
    for scanner.Scan() {
       line := scanner.Text()
       if line == `"id"` || line == "" {
          continue
       }
       sem <- 1
       id, err := strconv.Atoi(line[1:len([]byte(line))-1]) // 去除双引号
       if err != nil {
          fmt.Println(err)
       }
       count++
       if count % 10000 == 0 {
          fmt.Printf("%v ids processed\n", count)
       }
       go bizFunc(ctx, int64(id))
    }
    endTime := time.Now().Unix()
    fmt.Printf("cost time: %v", endTime - startTime)
}