diff --git a/dataset.go b/dataset.go
index 30aec0a..1065da6 100644
--- a/dataset.go
+++ b/dataset.go
@@ -10,6 +10,7 @@ type DataSet struct {
 	columns []string
 	values  []interface{}
 	numOfReaded int64
+	closed bool
 }
 
 //已读取函数(调用Next成功的次数)
@@ -17,7 +18,17 @@ func (this *DataSet) NumOfReaded() int64 {
 	return this.numOfReaded
 }
 
+func (this *DataSet) close() {
+	if this.rows != nil {
+		this.rows.Close()
+	}
+	this.closed = true
+}
+
 func (this *DataSet) Next() bool {
+	if this.closed {
+		panic("DataSet is closed")
+	}
 	ret := this.rows.Next()
 	if !ret {
 		return ret
diff --git a/dbpool.go b/dbpool.go
index 10462d7..1d31b54 100644
--- a/dbpool.go
+++ b/dbpool.go
@@ -91,6 +91,7 @@ func (this *dbPool) SelectCustomQuery(dataSource string, sql string, cb QueryRes
 
 func (this *dbPool) SyncSelectCustomQuery(dataSource string, sql string, cb QueryResultCb) {
 	chDone := make(chan bool)
+	chCbDone := make(chan bool)
 	params := []string{}
 	var e error
 	var d *DataSet
@@ -99,12 +100,20 @@ func (this *dbPool) SyncSelectCustomQuery(dataSource string, sql string, cb Quer
 			e = err
 			d = ds
 			chDone <- true
+			for {
+				select {
+				case <-chCbDone:
+					close(chCbDone)
+					return
+				}
+			}
 		})
 	for {
 		select {
 		case <-chDone:
 			close(chDone)
 			cb(e, d)
+			chCbDone <- true
 			return
 		}
 	}
@@ -387,8 +396,9 @@ func (this *dbPool) internalExec(dataSource string, sql string, params []string,
 		cb(errors.New("borrowConn error"), int64(0), int64(0))
 		return
 	}
-	result, err := ds.conn.Exec(sql, q5.ToInterfaces(params)...)
 	this.returnConn(ds)
+	result, err := ds.conn.Exec(sql, q5.ToInterfaces(params)...)
+	//this.returnConn(ds)
 
 	var lastInsertId int64
 	var rowsAffected int64
@@ -417,18 +427,31 @@ func (this *dbPool) internalQuery(dataSource string, sql string, params []string
 		cb(errors.New("borrowConn error"), nil)
 		return
 	}
-	rows, err := ds.conn.Query(sql, q5.ToInterfaces(params)...)
 	this.returnConn(ds)
+	rows, err := ds.conn.Query(sql, q5.ToInterfaces(params)...)
+	//this.returnConn(ds)
 	if err != nil {
 		GetSysLog().Warning("f5.dbpool.internalQuery error:%s sql:%s", err, sql)
 	}
 
+	var dataSet *DataSet
+	if err == nil {
+		dataSet = NewDataSet(rows)
+	}
+	freeFunc := func () {
+		if dataSet != nil {
+			dataSet.close()
+		}
+	}
+
 	if this.style == GO_STYLE_DB {
-		cb(err, NewDataSet(rows))
+		defer freeFunc()
+		cb(err, dataSet)
 	} else {
 		_app.RegisterMainThreadCb(
 			func() {
-				cb(err, NewDataSet(rows))
+				defer freeFunc()
+				cb(err, dataSet)
 			})
 	}
 }
@@ -440,13 +463,25 @@ func (this *dbPool) internalQueryNoMainThread(dataSource string, sql string, par
 		cb(errors.New("borrowConn error"), nil)
 		return
 	}
-	rows, err := ds.conn.Query(sql, q5.ToInterfaces(params)...)
 	this.returnConn(ds)
+	rows, err := ds.conn.Query(sql, q5.ToInterfaces(params)...)
+	//this.returnConn(ds)
 	if err != nil {
 		GetSysLog().Warning("f5.dbpool.internalQueryNoMainThread error:%s sql:%s", err, sql)
 	}
 
-	cb(err, NewDataSet(rows))
+	var dataSet *DataSet
+	if err == nil {
+		dataSet = NewDataSet(rows)
+	}
+	freeFunc := func () {
+		if dataSet != nil {
+			dataSet.close()
+		}
+	}
+
+	defer freeFunc()
+	cb(err, dataSet)
 }
 
 func (this *dbPool) internalQueryOne(dataSource string, sql string, params []string,
@@ -456,8 +491,9 @@ func (this *dbPool) internalQueryOne(dataSource string, sql string, params []str
 		cb(errors.New("borrowConn error"), nil)
 		return
 	}
-	rows, err := ds.conn.Query(sql, q5.ToInterfaces(params)...)
 	this.returnConn(ds)
+	rows, err := ds.conn.Query(sql, q5.ToInterfaces(params)...)
+	//this.returnConn(ds)
 	if err != nil {
 		GetSysLog().Warning("f5.dbpool.internalQueryOne error:%s sql:%s", err, sql)
 	}
@@ -466,12 +502,19 @@ func (this *dbPool) internalQueryOne(dataSource string, sql string, params []str
 	if err == nil {
 		dataSet = NewDataSet(rows)
 	}
+	freeFunc := func () {
+		if dataSet != nil {
+			dataSet.close()
+		}
+	}
 
 	if this.style == GO_STYLE_DB {
+		defer freeFunc()
 		cb(err, dataSet)
 	} else {
 		_app.RegisterMainThreadCb(
 			func() {
+				defer freeFunc()
 				cb(err, dataSet)
 			})
 	}