fix bug : concurrency error is modified by other goroutines

openark#1000

go/inst/instance_dao.go

@@ -294,6 +294,7 @@ func ReadTopologyInstanceBufferable(instanceKey *InstanceKey, bufferWrites bool,
 	isMaxScale := false
 	isMaxScale110 := false
 	slaveStatusFound := false
+	errorChan := make(chan error, 32)
 	var resolveErr error
 
 	if !instanceKey.IsValid() {
@@ -361,7 +362,7 @@ func ReadTopologyInstanceBufferable(instanceKey *InstanceKey, bufferWrites bool,
 				defer waitGroup.Done()
 				var dummy string
 				// show global status works just as well with 5.6 & 5.7 (5.7 moves variables to performance_schema)
-				err = db.QueryRow("show global status like 'Uptime'").Scan(&dummy, &instance.Uptime)
+				err := db.QueryRow("show global status like 'Uptime'").Scan(&dummy, &instance.Uptime)
 
 				if err != nil {
 					logReadTopologyInstanceError(instanceKey, "show global status like 'Uptime'", err)
@@ -373,6 +374,7 @@ func ReadTopologyInstanceBufferable(instanceKey *InstanceKey, bufferWrites bool,
 					// so as to completely fail reading a 5.7 instance.
 					// This is supposed to be fixed in 5.7.9
 				}
+				errorChan <- err
 			}()
 		}
 
@@ -402,27 +404,29 @@ func ReadTopologyInstanceBufferable(instanceKey *InstanceKey, bufferWrites bool,
 			waitGroup.Add(1)
 			go func() {
 				defer waitGroup.Done()
-				err = sqlutils.QueryRowsMap(db, "show master status", func(m sqlutils.RowMap) error {
+				err := sqlutils.QueryRowsMap(db, "show master status", func(m sqlutils.RowMap) error {
 					var err error
 					instance.SelfBinlogCoordinates.LogFile = m.GetString("File")
 					instance.SelfBinlogCoordinates.LogPos = m.GetInt64("Position")
 					return err
 				})
+				errorChan <- err
 			}()
 		}
 
 		{
 			waitGroup.Add(1)
 			go func() {
 				defer waitGroup.Done()
-				err = sqlutils.QueryRowsMap(db, "show global status like 'rpl_semi_sync_%_status'", func(m sqlutils.RowMap) error {
+				err := sqlutils.QueryRowsMap(db, "show global status like 'rpl_semi_sync_%_status'", func(m sqlutils.RowMap) error {
 					if m.GetString("Variable_name") == "Rpl_semi_sync_master_status" {
 						instance.SemiSyncMasterEnabled = (m.GetString("Value") == "ON")
 					} else if m.GetString("Variable_name") == "Rpl_semi_sync_slave_status" {
 						instance.SemiSyncReplicaEnabled = (m.GetString("Value") == "ON")
 					}
 					return nil
 				})
+				errorChan <- err
 			}()
 		}
 		if (instance.IsOracleMySQL() || instance.IsPercona()) && !instance.IsSmallerMajorVersionByString("5.6") {
@@ -806,6 +810,19 @@ func ReadTopologyInstanceBufferable(instanceKey *InstanceKey, bufferWrites bool,
 
 Cleanup:
 	waitGroup.Wait()
+	close(errorChan)
+	err = func() error {
+		if err != nil {
+			return err
+		}
+
+		for err := range errorChan {
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}()
 
 	if instanceFound {
 		if instance.IsCoMaster {