Drain event channel first (#967)

pkg/frontend/load.go

@@ -1472,9 +1472,6 @@ func (mce *MysqlCmdExecutor) LoadLoop(load *tree.Load, dbHandler engine.Database
 
 	wg.Wait()
 
-	//wait write to quit
-	handler.simdCsvWaitWriteRoutineToQuit.Wait()
-
 	/*
 		drain event channel
 	*/
@@ -1498,6 +1495,9 @@ func (mce *MysqlCmdExecutor) LoadLoop(load *tree.Load, dbHandler engine.Database
 		}
 	}
 
+	//wait write to quit
+	handler.simdCsvWaitWriteRoutineToQuit.Wait()
+
 	//fmt.Printf("-----total row2col %s fillBlank %s toStorage %s\n",
 	//	handler.row2col,handler.fillBlank,handler.toStorage)
 	//fmt.Printf("-----write batch %s reset batch %s\n",