reduce concurrent volume grow requests

weed/topology/volume_layout.go

@@ -114,6 +114,8 @@ type VolumeLayout struct {
 	volumeSizeLimit  uint64
 	replicationAsMin bool
 	accessLock       sync.RWMutex
+	growRequestCount int
+	growRequestTime  time.Time
 }
 
 type VolumeLayoutStats struct {
@@ -310,6 +312,21 @@ func (vl *VolumeLayout) PickForWrite(count uint64, option *VolumeGrowOption) (*n
 	return &vid, count, locationList, nil
 }
 
+func (vl *VolumeLayout) HasGrowRequest() bool {
+	if vl.growRequestCount > 0 && vl.growRequestTime.Add(time.Minute).After(time.Now()) {
+		return true
+	}
+	return false
+}
+func (vl *VolumeLayout) AddGrowRequest() {
+	vl.growRequestTime = time.Now()
+	vl.growRequestCount++
+}
+func (vl *VolumeLayout) DoneGrowRequest() {
+	vl.growRequestTime = time.Unix(0,0)
+	vl.growRequestCount = 0
+}
+
 func (vl *VolumeLayout) ShouldGrowVolumes(option *VolumeGrowOption) bool {
 	active, crowded := vl.GetActiveVolumeCount(option)
 	//glog.V(0).Infof("active volume: %d, high usage volume: %d\n", active, high)