kube-batch--启动过程

cmd/kube-batch/main.go:39 main -> cmd/kube-batch/main.go:53 app.Run
cmd/kube-batch/app/server.go:60 Run -> cmd/kube-batch/app/server.go:86 sched.Run
cmd/kube-batch/app/server.go:86 sched.Run-> pkg/scheduler/scheduler.go:59
cmd/kube-batch/app/server.go:59 sched.Run-> pkg/scheduler/scheduler.runOnce:84

cmd/kube-batch/app/server.go:59 代码

func (pc *Scheduler) Run(stopCh <-chan struct{}) {
    var err error

    // Start cache for policy.
    go pc.cache.Run(stopCh)
    pc.cache.WaitForCacheSync(stopCh)

    // Load configuration of scheduler
    schedConf := defaultSchedulerConf
    if len(pc.schedulerConf) != 0 {
        if schedConf, err = readSchedulerConf(pc.schedulerConf); err != nil {
            glog.Errorf("Failed to read scheduler configuration '%s', using default configuration: %v",
                pc.schedulerConf, err)
            schedConf = defaultSchedulerConf
        }
    }

    pc.actions, pc.plugins, err = loadSchedulerConf(schedConf)
    if err != nil {
        panic(err)
    }
    // 这里又开始周期性调用 runOnce了。开始调用
    go wait.Until(pc.runOnce, pc.schedulePeriod, stopCh)
}

cmd/kube-batch/app/server.go:84 代码

func (pc *Scheduler) runOnce() {
    glog.V(4).Infof("Start scheduling ...")
    scheduleStartTime := time.Now()
    defer glog.V(4).Infof("End scheduling ...")
    defer metrics.UpdateE2eDuration(metrics.Duration(scheduleStartTime))

    ssn := framework.OpenSession(pc.cache, pc.plugins)
    defer framework.CloseSession(ssn)

    for _, action := range pc.actions {
        actionStartTime := time.Now()
        action.Execute(ssn)
        metrics.UpdateActionDuration(action.Name(), metrics.Duration(actionStartTime))
    }
}

这里主要 defer 是延迟函数，就是返回值之前执行。所以上面的代码相当于

ssn := framework.OpenSession(pc.cache, pc.plugins)
for _, action := range pc.actions {
    actionStartTime := time.Now()
    action.Execute(ssn)
  metrics.UpdateActionDuration(action.Name(),metrics.Duration(actionStartTime))
}
framework.CloseSession(ssn)

每次开启一个回话，分别运行actions。这里其实就是前面说的kube-batch自己定义的四种Action.[Reclaim，Allocate，Backfill，Preempt]

到此为止，就知道kube-batch的启动过程了。