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将多个go例程的响应获取到一个数组中

goroutine concurrency go

kentor · 技术社区 · 7 年前

密码

func main() {
  log.Info("Collecting ints")
  var results []int32
  for _, broker := range e.BrokersByBrokerID {
      wg.Add(1)
      go getInt32(&wg)
  }
  wg.Wait()
  log.info("Collected")
}

func getInt32(wg *sync.WaitGroup) (int32, error) {
  defer wg.Done()

  // Just to show that this method may just return an error and no int32
  err := broker.Open(config)
  if err != nil && err != sarama.ErrAlreadyConnected {
    return 0, fmt.Errorf("Cannot connect to broker '%v': %s", broker.ID(), err)
  }
  defer broker.Close()

  return 1003, nil
}

我的问题

2 回复 | 直到 7 年前

icza 7 年前

如果不处理作为goroutine启动的函数的返回值,它们将被丢弃。看见 What happens to return value from goroutine .

您可以使用一个切片来收集结果,其中每个goroutine可以接收将结果放入的索引,或者接收元素的地址。看见 Can I concurrently write different slice elements . 请注意,如果使用此选项,则必须预先分配切片,并且只能写入属于goroutine的元素,不能“触摸”其他元素,也不能附加到切片。

或者您可以使用一个通道,goroutine在该通道上发送包含其处理的项的索引或ID的值,以便收集goroutine可以识别或排序它们。看见 How to collect values from N goroutines executed in a specific order?

Close multiple goroutine if an error occurs in one in go

下面是一个使用频道时的示例。请注意,此处不需要waitgroup,因为我们知道,我们希望通道上的值与我们启动的goroutine数量相同。

type result struct {
    task int32
    data int32
    err  error
}

func main() {
    tasks := []int32{1, 2, 3, 4}

    ch := make(chan result)

    for _, task := range tasks {
        go calcTask(task, ch)
    }

    // Collect results:
    results := make([]result, len(tasks))

    for i := range results {
        results[i] = <-ch
    }

    fmt.Printf("Results: %+v\n", results)
}

func calcTask(task int32, ch chan<- result) {
    if task > 2 {
        // Simulate failure
        ch <- result{task: task, err: fmt.Errorf("task %v failed", task)}
        return
    }

    // Simulate success
    ch <- result{task: task, data: task * 2, err: nil}
}

输出(在屏幕上尝试ot) Go Playground

Results: [{task:4 data:0 err:0x40e130} {task:1 data:2 err:<nil>} {task:2 data:4 err:<nil>} {task:3 data:0 err:0x40e138}]

cn007b Dheerendra Kulkarni 7 年前

package main

import (
    "fmt"
    "log"
    "sync"
)

var (
    BrokersByBrokerID = []int32{1, 2, 3}
)

type result struct {
    data string
    err string // you must use error type here
}

func main()  {
    var wg sync.WaitGroup
    var results []result
    ch := make(chan result)

    for _, broker := range BrokersByBrokerID {
        wg.Add(1)
        go getInt32(ch, &wg, broker)
    }

    go func() {
        for v := range ch {
            results = append(results, v)
        }
    }()

    wg.Wait()
    close(ch)

    log.Printf("collected %v", results)
}

func getInt32(ch chan result, wg *sync.WaitGroup, broker int32) {
    defer wg.Done()

    if broker == 1 {
        ch <- result{err: fmt.Sprintf("error: gor broker 1")}
        return
    }

    ch <- result{data: fmt.Sprintf("broker %d - ok", broker)}
}

结果如下所示:

2019/02/05 15:26:28 collected [{broker 3 - ok } {broker 2 - ok } { error: gor broker 1}]