remove old log files if they exist

benchmark_main.go

@@ -85,6 +85,16 @@ func main() {
 
 	// Setup a logger to stdout and log file.
 	logFileName := fmt.Sprintf("./%v/%v.log", *logFolder, *port)
+	_, err := os.Stat(logFileName)
+	if err == nil {
+		fmt.Printf("file %s exists", logFileName)
+		os.Remove(logFileName)
+		fmt.Printf("removed file %s", logFileName)
+	} else if os.IsNotExist(err) {
+		fmt.Printf("file %s not exists", logFileName)
+	} else {
+		fmt.Printf("file %s stat error: %v", logFileName, err)
+	}
 	h := log.MultiHandler(
 		log.Must.FileHandler(logFileName, log.LogfmtFormat()),
 		log.StdoutHandler)