workers = workers[:len(workers)-1]
		worker <- expiryOp(nil)
		es.stats.workers.Add(-1)
	}
	// Atomically replace workers.
	es.workers.Store(&workers)
}

// Worker handles 4 types of expiration tasks.
// 1. Expiry of objects, includes regular and transitioned objects
// 2. Expiry of noncurrent versions due to NewerNoncurrentVersions

	for len(p.workers) < n {
		input := make(chan ReplicationWorkerOperation, 10000)
		p.workers = append(p.workers, input)

		go p.AddWorker(input, &p.activeWorkers)
	}
	for len(p.workers) > n {
		worker := p.workers[len(p.workers)-1]
		p.workers = p.workers[:len(p.workers)-1]
		xioutil.SafeClose(worker)
	}
}

// ResizeWorkerPriority sets replication failed workers pool size

const (
	transitionWorkers = "transition_workers"
	expirationWorkers = "expiration_workers"
	// EnvILMTransitionWorkers env variable to configure number of transition workers
	EnvILMTransitionWorkers = "MINIO_ILM_TRANSITION_WORKERS"
	// EnvILMExpirationWorkers env variable to configure number of expiration workers
	EnvILMExpirationWorkers = "MINIO_ILM_EXPIRATION_WORKERS"
)

var (
	defaultHelpPostfix = func(key string) string {

	apiRemoteTransportDeadline = "remote_transport_deadline"
	apiListQuorum              = "list_quorum"
	apiReplicationPriority     = "replication_priority"
	apiReplicationMaxWorkers   = "replication_max_workers"

	apiTransitionWorkers           = "transition_workers"
	apiStaleUploadsCleanupInterval = "stale_uploads_cleanup_interval"
	apiStaleUploadsExpiry          = "stale_uploads_expiry"
	apiDeleteCleanupInterval       = "delete_cleanup_interval"

const (
	Bitrot       = "bitrotscan"
	Sleep        = "max_sleep"
	IOCount      = "max_io"
	DriveWorkers = "drive_workers"

	EnvBitrot       = "MINIO_HEAL_BITROTSCAN"
	EnvSleep        = "MINIO_HEAL_MAX_SLEEP"
	EnvIOCount      = "MINIO_HEAL_MAX_IO"
	EnvDriveWorkers = "MINIO_HEAL_DRIVE_WORKERS"
)

var configMutex sync.RWMutex

// Config represents the heal settings.
type Config struct {

	sync.RWMutex                 // mutex for Cache
	mostRecentStatsMu sync.Mutex // mutex for mostRecentStats

	wlock sync.RWMutex // mutex for active workers

	movingAvgTicker *time.Ticker // Ticker for calculating moving averages
	wTimer          *time.Ticker // ticker for calculating active workers
	qTimer          *time.Ticker // ticker for calculating queue stats
}

func (r *ReplicationStats) trackEWMA() {
	for {
		select {

	es := newExpiryState(context.Background(), objAPI, 0)
	workers := []chan expiryOp{make(chan expiryOp)}
	es.workers.Store(&workers)
	globalExpiryState = es
	var wg sync.WaitGroup
	wg.Add(1)
	expired := make([]ObjectToDelete, 0, 5)
	go func() {
		defer wg.Done()
		workers := globalExpiryState.workers.Load()
		for t := range (*workers)[0] {
			if t, ok := t.(newerNoncurrentTask); ok {

					return
				}
			}
		}()
	}
	wk.Wait()
}

var startOnce sync.Once

// Init initialize target send workers.
func (list *TargetList) Init(workers int) *TargetList {
	startOnce.Do(func() {
		go list.startSendWorkers(workers)
	})
	return list
}

// NewTargetList - creates TargetList.
func NewTargetList(ctx context.Context) *TargetList {
	list := &TargetList{

	lastObject := ri.Object

	now := time.Now().UTC()

	workerSize, err := strconv.Atoi(env.Get("_MINIO_BATCH_EXPIRATION_WORKERS", strconv.Itoa(runtime.GOMAXPROCS(0)/2)))
	if err != nil {
		return err
	}

	wk, err := workers.New(workerSize)
	if err != nil {
		// invalid worker size.
		return err
	}

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	current      [][]string       // current block of results to be returned
	recordsRead  int              // number of records read in current slice
	input        chan *queueItem  // input for workers
	queue        chan *queueItem  // output from workers in order
	err          error            // global error state, only touched by Reader.Read
	bufferPool   sync.Pool        // pool of []byte objects for input