[master] do sync grow request only if absolutely necessary (#5821)

* do sync grow request only if absolutely necessary
https://github.com/seaweedfs/seaweedfs/pull/5819

* remove check VolumeGrowStrategy Threshold on PickForWrite

* fix fmt.Errorf

weed/server/master_grpc_server_assign.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/stats"
 	"time"
 
 	"github.com/seaweedfs/raft"
@@ -85,9 +86,8 @@ func (ms *MasterServer) Assign(ctx context.Context, req *master_pb.AssignRequest
 	for time.Now().Sub(startTime) < maxTimeout {
 		fid, count, dnList, shouldGrow, err := ms.Topo.PickForWrite(req.Count, option, vl)
 		if shouldGrow && !vl.HasGrowRequest() {
-			// if picked volume is almost full, trigger a volume-grow request
-			if ms.Topo.AvailableSpaceFor(option) <= 0 {
-				return nil, fmt.Errorf("no free volumes left for " + option.String())
+			if err != nil && ms.Topo.AvailableSpaceFor(option) <= 0 {
+				err = fmt.Errorf("%s and no free volumes left for %s", err.Error(), option.String())
 			}
 			vl.AddGrowRequest()
 			ms.volumeGrowthRequestChan <- &topology.VolumeGrowRequest{
@@ -96,7 +96,7 @@ func (ms *MasterServer) Assign(ctx context.Context, req *master_pb.AssignRequest
 			}
 		}
 		if err != nil {
-			// glog.Warningf("PickForWrite %+v: %v", req, err)
+			stats.MasterPickForWriteErrorCounter.Inc()
 			lastErr = err
 			time.Sleep(200 * time.Millisecond)
 			continue

weed/server/master_server_handlers.go

@@ -143,11 +143,9 @@ func (ms *MasterServer) dirAssignHandler(w http.ResponseWriter, r *http.Request)
 	for time.Now().Sub(startTime) < maxTimeout {
 		fid, count, dnList, shouldGrow, err := ms.Topo.PickForWrite(requestedCount, option, vl)
 		if shouldGrow && !vl.HasGrowRequest() {
-			// if picked volume is almost full, trigger a volume-grow request
 			glog.V(0).Infof("dirAssign volume growth %v from %v", option.String(), r.RemoteAddr)
-			if ms.Topo.AvailableSpaceFor(option) <= 0 {
-				writeJsonQuiet(w, r, http.StatusNotFound, operation.AssignResult{Error: "No free volumes left for " + option.String()})
-				return
+			if err != nil && ms.Topo.AvailableSpaceFor(option) <= 0 {
+				err = fmt.Errorf("%s and no free volumes left for %s", err.Error(), option.String())
 			}
 			vl.AddGrowRequest()
 			ms.volumeGrowthRequestChan <- &topology.VolumeGrowRequest{
@@ -156,7 +154,7 @@ func (ms *MasterServer) dirAssignHandler(w http.ResponseWriter, r *http.Request)
 			}
 		}
 		if err != nil {
-			// glog.Warningf("PickForWrite %+v: %v", req, err)
+			stats.MasterPickForWriteErrorCounter.Inc()
 			lastErr = err
 			time.Sleep(200 * time.Millisecond)
 			continue

weed/stats/metrics.go

@@ -78,6 +78,14 @@ var (
 			Help:      "Number of volumes in volume layouts",
 		}, []string{"collection", "dataCenter", "type"})
 
+	MasterPickForWriteErrorCounter = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Namespace: Namespace,
+			Subsystem: "master",
+			Name:      "pick_for_write_error",
+			Help:      "Counter of master pick for write error",
+		})
+
 	MasterLeaderChangeCounter = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Namespace: Namespace,

weed/topology/topology.go

@@ -251,8 +251,8 @@ func (t *Topology) PickForWrite(requestedCount uint64, option *VolumeGrowOption,
 	if err != nil {
 		return "", 0, nil, shouldGrow, fmt.Errorf("failed to find writable volumes for collection:%s replication:%s ttl:%s error: %v", option.Collection, option.ReplicaPlacement.String(), option.Ttl.String(), err)
 	}
-	if volumeLocationList.Length() == 0 {
-		return "", 0, nil, shouldGrow, fmt.Errorf("no writable volumes available for collection:%s replication:%s ttl:%s", option.Collection, option.ReplicaPlacement.String(), option.Ttl.String())
+	if volumeLocationList == nil || volumeLocationList.Length() == 0 {
+		return "", 0, nil, shouldGrow, fmt.Errorf("%s available for collection:%s replication:%s ttl:%s", noWritableVolumes, option.Collection, option.ReplicaPlacement.String(), option.Ttl.String())
 	}
 	nextFileId := t.Sequence.NextFileId(requestedCount)
 	fileId = needle.NewFileId(vid, nextFileId, rand.Uint32()).String()

weed/topology/volume_layout.go

@@ -1,7 +1,6 @@
 package topology
 
 import (
-	"errors"
 	"fmt"
 	"github.com/seaweedfs/seaweedfs/weed/stats"
 	"math/rand"
@@ -31,6 +30,7 @@ const (
 	readOnlyState     volumeState = "ReadOnly"
 	oversizedState                = "Oversized"
 	crowdedState                  = "Crowded"
+	noWritableVolumes             = "No writable volumes"
 )
 
 type stateIndicator func(copyState) bool
@@ -293,23 +293,15 @@ func (vl *VolumeLayout) PickForWrite(count uint64, option *VolumeGrowOption) (vi
 
 	lenWriters := len(vl.writables)
 	if lenWriters <= 0 {
-		//glog.V(0).Infoln("No more writable volumes!")
-		shouldGrow = true
-		return 0, 0, nil, shouldGrow, errors.New("No more writable volumes!")
+		return 0, 0, nil, true, fmt.Errorf("%s in volume layout", noWritableVolumes)
 	}
 	if option.DataCenter == "" && option.Rack == "" && option.DataNode == "" {
 		vid := vl.writables[rand.Intn(lenWriters)]
 		locationList = vl.vid2location[vid]
-		if locationList != nil && locationList.Length() > 0 {
-			// check whether picked file is close to full
-			dn := locationList.Head()
-			info, _ := dn.GetVolumesById(vid)
-			if float64(info.Size) > float64(vl.volumeSizeLimit)*VolumeGrowStrategy.Threshold {
-				shouldGrow = true
-			}
-			return vid, count, locationList.Copy(), shouldGrow, nil
+		if locationList == nil || len(locationList.list) == 0 {
+			return 0, 0, nil, false, fmt.Errorf("Strangely vid %s is on no machine!", vid.String())
 		}
-		return 0, 0, nil, shouldGrow, errors.New("Strangely vid " + vid.String() + " is on no machine!")
+		return vid, count, locationList.Copy(), false, nil
 	}
 
 	// clone vl.writables
@@ -332,17 +324,11 @@ func (vl *VolumeLayout) PickForWrite(count uint64, option *VolumeGrowOption) (vi
 			if option.DataNode != "" && dn.Id() != NodeId(option.DataNode) {
 				continue
 			}
-			vid, locationList = writableVolumeId, volumeLocationList.Copy()
-			// check whether picked file is close to full
-			info, _ := dn.GetVolumesById(writableVolumeId)
-			if float64(info.Size) > float64(vl.volumeSizeLimit)*VolumeGrowStrategy.Threshold {
-				shouldGrow = true
-			}
-			counter = count
+			vid, locationList, counter = writableVolumeId, volumeLocationList.Copy(), count
 			return
 		}
 	}
-	return vid, count, locationList, true, fmt.Errorf("No writable volumes in DataCenter:%v Rack:%v DataNode:%v", option.DataCenter, option.Rack, option.DataNode)
+	return vid, count, locationList, true, fmt.Errorf("%s in DataCenter:%v Rack:%v DataNode:%v", noWritableVolumes, option.DataCenter, option.Rack, option.DataNode)
 }
 
 func (vl *VolumeLayout) HasGrowRequest() bool {