diff --git a/cmd/demo/main.go b/cmd/demo/main.go
index 2c59cf2..bccbe75 100644
--- a/cmd/demo/main.go
+++ b/cmd/demo/main.go
@@ -313,7 +313,7 @@ func main() {
 			sos := op.NewSoS(name, &hedge.SoSOptions{
 				MemLimit:   150_000,
 				DiskLimit:  120_000,
-				Expiration: 30,
+				Expiration: 5,
 			})
 
 			writer, err := sos.Writer()
@@ -448,9 +448,11 @@ func main() {
 			Usage         float64 `json:"usage"`
 		}
 
+		// See $HOME/tmp/
 		locs, _ := os.ReadFile("readlocs")
 		ss := strings.Split(string(locs), " ")
 
+		// See $HOME/tmp/
 		ra, err := mmap.Open("readdata")
 		if err != nil {
 			slog.Error(err.Error())
@@ -469,8 +471,9 @@ func main() {
 
 		sos := func() *hedge.SoS {
 			sos := op.NewSoS(name, &hedge.SoSOptions{
-				MemLimit:   100_000,
-				Expiration: 30,
+				MemLimit:   10_000_000,
+				DiskLimit:  10_000_000,
+				Expiration: 5,
 			})
 
 			writer, err := sos.Writer()
@@ -511,6 +514,7 @@ func main() {
 
 			writer.Close()
 			slog.Info("total_write:",
+				"count", i,
 				"val", wt,
 				"err", writer.Err(),
 			)
@@ -541,7 +545,7 @@ func main() {
 					rt += len(d)
 				}
 
-				slog.Info("total_read:", "val", rt)
+				slog.Info("total_read:", "count", i, "val", rt)
 				return nil
 			})
 
diff --git a/sos.go b/sos.go
index 1ddecbb..a9f74ad 100644
--- a/sos.go
+++ b/sos.go
@@ -85,6 +85,7 @@ type SoS struct {
 	dlock  *sync.Mutex       // local file lock
 	wmtx   *sync.Mutex       // one active writer only
 	writer *Writer           // writer object
+	refs   atomic.Int64      // self reference count
 	wrefs  atomic.Int64      // writer reference count
 	rrefs  atomic.Int64      // reader reference count
 	on     atomic.Int32
@@ -288,6 +289,8 @@ func (w *Writer) start() {
 		if w.sos.data[n].bb != nil {
 			w.sos.data[n].bufs = w.sos.data[n].bb.NewBinaryArray()
 			w.sos.data[n].bb.Release()
+			w.sos.data[n].bb = nil
+			// slog.Info("arrow: release(bb):", "node", n)
 		}
 	}
 
@@ -519,6 +522,7 @@ func (sos *SoS) Close() {
 		}
 	}
 
+	sos.refs.Add(-1)
 	sos.on.Store(0)
 }
 
@@ -558,10 +562,11 @@ func (sos *SoS) cleaner() {
 	eg.Go(func() error {
 		started := sos.start
 		for {
-			time.Sleep(time.Second * 5)
+			time.Sleep(time.Second * 1)
+			refs := sos.refs.Load()
 			wrefs := sos.wrefs.Load()
 			rrefs := sos.rrefs.Load()
-			if (wrefs + rrefs) > 0 {
+			if (refs + wrefs + rrefs) > 0 {
 				started = time.Now()
 				continue
 			}
@@ -574,7 +579,8 @@ func (sos *SoS) cleaner() {
 					for _, node := range sos.op.soss[sos.Name].nodes {
 						if sos.data[node].bufs != nil {
 							sos.data[node].bufs.Release()
-							// slog.Info("arrow: release:", "node", node)
+							sos.data[node].bufs = nil
+							// slog.Info("arrow: release(buf):", "node", node)
 						}
 					}
 				}()
@@ -636,6 +642,7 @@ func newSoS(name string, op *Op, opts ...*SoSOptions) *SoS {
 		sos.age = time.Hour * 1
 	}
 
+	sos.refs.Add(1)
 	sos.start = time.Now()
 	go sos.cleaner()
 	return sos