}
	for {
		lockWithRank(&root.lock, lockRankRoot)
		// Add ourselves to nwait to disable "easy case" in semrelease.
		root.nwait.Add(1)
		// Check cansemacquire to avoid missed wakeup.
		if cansemacquire(addr) {
			root.nwait.Add(-1)
			unlock(&root.lock)
			break
		}
		// Any semrelease after the cansemacquire knows we're waiting
		// (we set nwait above), so go to sleep.
		root.queue(addr, s, lifo)

	// will be, so we pretend to have an arbitrarily large number
	// of workers, almost all of which are "waiting". While a
	// worker is working it decrements nwait. If nproc == nwait,
	// there are no workers.
	work.nproc = ^uint32(0)
	work.nwait = ^uint32(0)
}

// gcBgMarkWorkerNode is an entry in the gcBgMarkWorkerPool. It points to a single
// gcBgMarkWorker goroutine.
type gcBgMarkWorkerNode struct {

	startTime := nanotime()
	trackLimiterEvent := gp.m.p.ptr().limiterEvent.start(limiterEventMarkAssist, startTime)

	decnwait := atomic.Xadd(&work.nwait, -1)
	if decnwait == work.nproc {
		println("runtime: work.nwait =", decnwait, "work.nproc=", work.nproc)
		throw("nwait > work.nprocs")
	}

	// gcDrainN requires the caller to be preemptible.
	casGToWaitingForGC(gp, _Grunning, waitReasonGCAssistMarking)

	return &root.lock
}

var Semacquire = semacquire
var Semrelease1 = semrelease1

func SemNwait(addr *uint32) uint32 {
	root := semtable.rootFor(addr)
	return root.nwait.Load()
}

const SemTableSize = semTabSize

// SemTable is a wrapper around semTable exported for testing.
type SemTable struct {
	semTable
}

  istioctl experimental wait --for=distribution virtualservice bookinfo.default

  # Wait until the bookinfo virtual service has been distributed to a specific proxy
  istioctl experimental wait --for=distribution virtualservice bookinfo.default --proxy workload-instance.namespace

  # Wait until 99% of the proxies receive the distribution, timing out after 5 minutes

// NeverStop may be passed to Until to make it never stop.
var NeverStop <-chan struct{} = make(chan struct{})

// Group allows to start a group of goroutines and wait for their completion.
type Group struct {
	wg sync.WaitGroup
}

func (g *Group) Wait() {
	g.wg.Wait()
}

// StartWithChannel starts f in a new goroutine in the group.
// stopCh is passed to f as an argument. f should stop when stopCh is available.

	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/kubernetes"
	kctldeployment "k8s.io/kubectl/pkg/util/deployment"

	"istio.io/istio/operator/pkg/name"
	"istio.io/istio/operator/pkg/object"
	"istio.io/istio/operator/pkg/util/progress"
	"istio.io/istio/pkg/kube"
)

const (
	// defaultWaitResourceTimeout is the maximum wait time for all resources(namespace/deployment/pod) to be created.

	waitCmd.PersistentFlags().IntVar(&timeoutSeconds, "timeoutSeconds", 60, "maximum number of seconds to wait for Envoy to be ready")
	waitCmd.PersistentFlags().IntVar(&requestTimeoutMillis, "requestTimeoutMillis", 500, "number of milliseconds to wait for response")
	waitCmd.PersistentFlags().IntVar(&periodMillis, "periodMillis", 500, "number of milliseconds to wait between attempts")

	return nil
}

// WaitForPodsWithLabel will lookup pods with the given label and wait until they are all
// reporting status as running.
func (w *KubeWaiter) WaitForPodsWithLabel(kvLabel string) error {

	lastKnownPodNumber := -1
	return wait.PollUntilContextTimeout(context.Background(),
		constants.KubernetesAPICallRetryInterval, w.timeout,

	time.Sleep(100 * time.Millisecond)

	// Write to the pipe to unblock it.
	if _, err := syscall.Write(wfd, []byte{10}); err != nil {
		log.Fatalf("failed to write to pipe: %v", err)
	}

	// Wait for the goroutine to unblock and start running.
	// This is helpful to catch incorrect information written
	// down for the syscall-blocked goroutine, since it'll start
	// executing, and that execution information will be