if responses == nil {
		return nil, errors.New("RequestStream: responses channel is nil")
	}
	m.init = true
	m.respMu.Lock()
	if m.closed {
		m.respMu.Unlock()
		return nil, ErrDisconnected
	}
	m.respWait = responses // Route directly to output.
	m.respMu.Unlock()

	// Try to grab an initial block.
	m.singleResp = false
	m.RecvSeq = m.SendSeq // Sync
	if cap(requests) > 0 {

	// Attempt all calls.
	_, err = lkClient.RLock(context.Background(), dsync.LockArgs{})
	if err == nil {
		t.Fatal("Expected for Rlock to fail")
	}

	_, err = lkClient.Lock(context.Background(), dsync.LockArgs{})
	if err == nil {
		t.Fatal("Expected for Lock to fail")
	}

	_, err = lkClient.RUnlock(context.Background(), dsync.LockArgs{})
	if err == nil {
		t.Fatal("Expected for RUnlock to fail")
	}

type IAMStorageAPI interface {
	// The role of the read-write lock is to prevent go routines from
	// concurrently reading and writing the IAM storage. The (r)lock()
	// functions return the iamCache. The cache can be safely written to
	// only when returned by `lock()`.
	lock() *iamCache
	unlock()
	rlock() *iamCache
	runlock()
	getUsersSysType() UsersSysType

}

func (t *tierMetrics) logSuccess(tier string) {
	t.Lock()
	defer t.Unlock()

	stat := t.requestsCount[tier]
	stat.success++
	t.requestsCount[tier] = stat
}

func (t *tierMetrics) logFailure(tier string) {
	t.Lock()
	defer t.Unlock()

	stat := t.requestsCount[tier]
	stat.failure++
	t.requestsCount[tier] = stat
}

var (

				//
				// - Do not consume disks which are being healed
				//
				// - Future: skip busy disks
				return
			}

			mu.Lock()
			newDisks = append(newDisks, disks[i])
			mu.Unlock()
		}()
	}
	wg.Wait()
	return newDisks
}

func (er erasureObjects) getOnlineLocalDisks() (newDisks []StorageAPI) {
	disks := er.getOnlineDisks()

func (m *bucketMeasurement) updateExponentialMovingAverage(endTime time.Time) {
	// Calculate aggregate avg bandwidth and exp window avg
	m.lock.Lock()
	defer func() {
		m.startTime = endTime
		m.lock.Unlock()
	}()

	if m.startTime.IsZero() {
		return
	}

	if endTime.Before(m.startTime) {
		return
	}

	duration := endTime.Sub(m.startTime)

	}
}

func (restClient *ReconnectRESTClient) RLock(ctx context.Context, args LockArgs) (status bool, err error) {
	return restClient.Call("/v1/rlock", args)
}

func (restClient *ReconnectRESTClient) Lock(ctx context.Context, args LockArgs) (status bool, err error) {
	return restClient.Call("/v1/lock", args)
}

func (restClient *ReconnectRESTClient) RUnlock(ctx context.Context, args LockArgs) (status bool, err error) {

	}

	// if no update is needed return right away.
	if !update {
		z.poolMetaMutex.Lock()
		z.poolMeta = meta
		z.poolMetaMutex.Unlock()
	} else {
		newMeta := newPoolMeta(z, meta)
		if err = newMeta.save(ctx, z.serverPools); err != nil {
			return err
		}
		z.poolMetaMutex.Lock()
		z.poolMeta = newMeta
		z.poolMetaMutex.Unlock()
	}

	pools := meta.returnResumablePools()

	if r == nil {
		return nil
	}
	r.Lock()
	defer r.Unlock()
	r.tags = append(r.tags, KeyVal{key, val})
	return r
}

// SetTags - sets key/val to ReqInfo.tags
func (r *ReqInfo) SetTags(key string, val interface{}) *ReqInfo {
	if r == nil {
		return nil
	}
	r.Lock()
	defer r.Unlock()
	// Search of tag key already exists in tags
	var updated bool

		latestDriveStats[d] = dm.IOStats
	}
	lastDriveStatsRefresh = time.Now().UTC()
	latestDriveStatsMu.Unlock()

	globalLocalDrivesMu.RLock()
	localDrives := cloneDrives(globalLocalDrives)
	globalLocalDrivesMu.RUnlock()

	for _, d := range localDrives {
		di, err := d.DiskInfo(GlobalContext, DiskInfoOptions{})
		labels := map[string]string{"drive": di.Endpoint}
		if err == nil {