动态保活Goroutine Pool设计

package main

import "fmt"

type WorkerManager struct {
   //用来监控Worker是否已经死亡的缓冲Channel
   workerChan chan *worker
   // 一共要监控的worker数量
   nWorkers int
}

//创建一个WorkerManager对象
func NewWorkerManager(nworkers int) *WorkerManager {
   return &WorkerManager{
      nWorkers:   nworkers,
      workerChan: make(chan *worker, nworkers),
   }
}

//启动worker池，并为每个Worker分配一个ID，让每个Worker进行工作
func (wm *WorkerManager) StartWorkerPool() {
   //开启一定数量的Worker
   for i := 0; i < wm.nWorkers; i++ {
      i := i
      wk := &worker{id: i}
      go wk.work(wm.workerChan)
   }
   //启动保活监控
   wm.KeepLiveWorkers()
}

//保活监控workers
func (wm *WorkerManager) KeepLiveWorkers() {
   //如果有worker已经死亡 workChan会得到具体死亡的worker然后 打出异常，然后重启
   for wk := range wm.workerChan {
      // log the error
      fmt.Printf("Worker %d stopped with err: [%v] \n", wk.id, wk.err)
      // reset err
      wk.err = nil
      // 当前这个wk已经死亡了，需要重新启动他的业务
      go wk.work(wm.workerChan)
   }
}

type worker struct {
   id  int
   err error
}

func (wk worker) work(workerChan chan<- worker) (err error) {
   // 任何Goroutine只要异常退出或者正常退出 都会调用defer 函数，所以在defer中想WorkerManager的WorkChan发送通知
   defer func() {
      //捕获异常信息，防止panic直接退出
      if r := recover(); r != nil {
         if err, ok := r.(error); ok {
            wk.err = err
         } else {
            wk.err = fmt.Errorf("Panic happened with[ % v]", r)
         }
      } else {
         wk.err = err
      }
      //通知 主 Goroutine，当前子Goroutine已经死亡
      workerChan <- wk
   }()
   // do something
   fmt.Println("Start Worker…ID = ", wk.id)
   // 每个worker睡眠一定时间之后，panic退出或者 Goexit()退出 for i := 0; i < 5; i++ { time.Sleep(time.Second*1) }
   panic("worker panic..")
   //runtime.Goexit()
   return err
}

func main() {
   wm := NewWorkerManager(10)
   wm.StartWorkerPool()
}