diff --git a/weed/util/mem/slot_pool.go b/weed/util/mem/slot_pool.go
index e6680d3cb..d5a55f23f 100644
--- a/weed/util/mem/slot_pool.go
+++ b/weed/util/mem/slot_pool.go
@@ -1,6 +1,10 @@
 package mem
 
-import "sync"
+import (
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"sync"
+	"sync/atomic"
+)
 
 var pools []*sync.Pool
 
@@ -34,11 +38,17 @@ func getSlotPool(size int) *sync.Pool {
 	return pools[index]
 }
 
+var total int64
+
 func Allocate(size int) []byte {
+	newVal := atomic.AddInt64(&total, 1)
+	glog.V(4).Infof("++> %d", newVal)
 	slab := *getSlotPool(size).Get().(*[]byte)
 	return slab[:size]
 }
 
 func Free(buf []byte) {
+	newVal := atomic.AddInt64(&total, -1)
+	glog.V(4).Infof("--> %d", newVal)
 	getSlotPool(cap(buf)).Put(&buf)
 }