diff --git a/capture/network.go b/capture/network.go
index 33cdedc..b063389 100644
--- a/capture/network.go
+++ b/capture/network.go
@@ -93,13 +93,6 @@ func initEthernetHandlerFromPacp() (handler *pcap.Handle) {
 }
 
 func (nc *networkCard) Listen() (receiver chan model.QueryPiece) {
-	// if inParallel {
-	// 	nc.listenInParallel()
-	//
-	// } else {
-	// 	nc.listenNormal()
-	// }
-
 	nc.listenNormal()
 	return nc.receiver
 }
@@ -163,62 +156,6 @@ func (nc *networkCard) listenNormal() {
 	return
 }
 
-// Listen get a connection.
-func (nc *networkCard) listenInParallel() {
-	type captureInfo struct {
-		bytes []byte
-		captureInfo gopacket.CaptureInfo
-	}
-
-	rawDataChan := make(chan *captureInfo, 20)
-	packageChan := make(chan gopacket.Packet, 20)
-
-	// read packet
-	go func() {
-		defer func() {
-			close(packageChan)
-		}()
-
-		handler := initEthernetHandlerFromPacpgo()
-		for {
-			var data []byte
-			// data, ci, err := handler.ZeroCopyReadPacketData()
-			data, ci, err := handler.ReadPacketData()
-			if err != nil {
-				log.Error(err.Error())
-				time.Sleep(time.Second*3)
-				continue
-			}
-
-			rawDataChan <- &captureInfo{
-				bytes: data,
-				captureInfo: ci,
-			}
-		}
-	}()
-
-	// parse package
-	go func() {
-		for captureInfo := range rawDataChan {
-			packet := gopacket.NewPacket(captureInfo.bytes, layers.LayerTypeEthernet, gopacket.NoCopy)
-			m := packet.Metadata()
-			m.CaptureInfo = captureInfo.captureInfo
-			m.Truncated = m.Truncated || captureInfo.captureInfo.CaptureLength < captureInfo.captureInfo.Length
-
-			packageChan <- packet
-		}
-	}()
-
-	// parse package
-	go func() {
-		for packet := range packageChan {
-			nc.parseTCPPackage(packet)
-		}
-	}()
-
-	return
-}
-
 func (nc *networkCard) parseTCPPackage(packet gopacket.Packet) {
 	var err error
 	defer func() {
diff --git a/model/cache_pool.go b/model/cache_pool.go
index 8e5e348..8019211 100644
--- a/model/cache_pool.go
+++ b/model/cache_pool.go
@@ -30,7 +30,12 @@ func (sbp *sliceBufferPool) Enqueue(buffer []byte)  {
 		return
 	}
 
-	sbp.queue <- buffer
+	select {
+	case sbp.queue <- buffer:
+		return
+	default:
+		buffer = nil
+	}
 }
 
 func (sbp *sliceBufferPool) DequeueWithInit(initSize int) (buffer []byte)  {
diff --git a/model/query_piece_pool.go b/model/query_piece_pool.go
index 3155cd5..de3fabf 100644
--- a/model/query_piece_pool.go
+++ b/model/query_piece_pool.go
@@ -19,7 +19,13 @@ func (mqpp *mysqlQueryPiecePool) Enqueue(pmqp *PooledMysqlQueryPiece)  {
 	mqpp.lock.Lock()
 	defer mqpp.lock.Unlock()
 
-	mqpp.queue <- pmqp
+	select {
+	case mqpp.queue <- pmqp:
+		return
+	default:
+		pmqp = nil
+		return
+	}
 }
 
 func (mqpp *mysqlQueryPiecePool) Dequeue() (pmqp *PooledMysqlQueryPiece)  {
@@ -29,6 +35,7 @@ func (mqpp *mysqlQueryPiecePool) Dequeue() (pmqp *PooledMysqlQueryPiece)  {
 	select {
 	case pmqp = <- mqpp.queue:
 		return
+
 	default:
 		pmqp = &PooledMysqlQueryPiece{
 			MysqlQueryPiece: MysqlQueryPiece{},
diff --git a/session-dealer/mysql/cover_range.go b/session-dealer/mysql/cover_range.go
index 7654c30..da5b4bb 100644
--- a/session-dealer/mysql/cover_range.go
+++ b/session-dealer/mysql/cover_range.go
@@ -100,13 +100,19 @@ func (crp *coveragePool) NewCoverage(begin, end int64)(cn *coverageNode)  {
 	return
 }
 
-func (crp *coveragePool) Enqueue(cn *coverageNode)  {
+func (crp *coveragePool) Enqueue(cn *coverageNode) {
 	// log.Debugf("coveragePool enqueue: %d", len(crp.queue))
 	if cn == nil {
 		return
 	}
 
-	crp.queue <- cn
+	select {
+	case crp.queue <- cn:
+		return
+
+	default:
+		cn = nil
+	}
 }
 
 func (crp *coveragePool) Dequeue() (cn *coverageNode)  {
@@ -122,6 +128,7 @@ func (crp *coveragePool) Dequeue() (cn *coverageNode)  {
 	select {
 	case cn = <- crp.queue:
 		return
+
 	default:
 		cn = &coverageNode{}
 		return