@@ -94,7 +94,6 @@ func (l *JSONFileLogger) Log(msg *logger.Message) error {

 		return err

 	}

 	l.mu.Lock()

-	defer l.mu.Unlock()

 	err = (&jsonlog.JSONLogs{

 		Log:      append(msg.Line, '\n'),

 		Stream:   msg.Source,

@@ -102,6 +101,7 @@ func (l *JSONFileLogger) Log(msg *logger.Message) error {

 		RawAttrs: l.extra,

 	}).MarshalJSONBuf(l.buf)

 	if err != nil {

+		l.mu.Unlock()

 		return err

 	}

@@ -109,6 +109,7 @@ func (l *JSONFileLogger) Log(msg *logger.Message) error {

 	_, err = l.writer.Write(l.buf.Bytes())

 	l.writeNotifier.Publish(struct{}{})

 	l.buf.Reset()

+	l.mu.Unlock()

 	return err

 }

@@ -13,6 +13,7 @@ type RotateFileWriter struct {

 	f            *os.File // store for closing

 	mu           sync.Mutex

 	capacity     int64 //maximum size of each file

+	currentSize  int64 // current size of the latest file

 	maxFiles     int   //maximum number of files

 	notifyRotate *pubsub.Publisher

 }

@@ -21,12 +22,18 @@ type RotateFileWriter struct {

 func NewRotateFileWriter(logPath string, capacity int64, maxFiles int) (*RotateFileWriter, error) {

 	log, err := os.OpenFile(logPath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0640)

 	if err != nil {

-		return &RotateFileWriter{}, err

+		return nil, err

+	}

+

+	size, err := log.Seek(0, os.SEEK_END)

+	if err != nil {

+		return nil, err

 	}

 	return &RotateFileWriter{

 		f:            log,

 		capacity:     capacity,

+		currentSize:  size,

 		maxFiles:     maxFiles,

 		notifyRotate: pubsub.NewPublisher(0, 1),

 	}, nil

@@ -35,12 +42,17 @@ func NewRotateFileWriter(logPath string, capacity int64, maxFiles int) (*RotateF

 //WriteLog write log message to File

 func (w *RotateFileWriter) Write(message []byte) (int, error) {

 	w.mu.Lock()

-	defer w.mu.Unlock()

 	if err := w.checkCapacityAndRotate(); err != nil {

+		w.mu.Unlock()

 		return -1, err

 	}

-	return w.f.Write(message)

+	n, err := w.f.Write(message)

+	if err == nil {

+		w.currentSize += int64(n)

+	}

+	w.mu.Unlock()

+	return n, err

 }

 func (w *RotateFileWriter) checkCapacityAndRotate() error {

@@ -48,12 +60,7 @@ func (w *RotateFileWriter) checkCapacityAndRotate() error {

 		return nil

 	}

-	meta, err := w.f.Stat()

-	if err != nil {

-		return err

-	}

-

-	if meta.Size() >= w.capacity {

+	if w.currentSize >= w.capacity {

 		name := w.f.Name()

 		if err := w.f.Close(); err != nil {

 			return err

@@ -66,6 +73,7 @@ func (w *RotateFileWriter) checkCapacityAndRotate() error {

 			return err

 		}

 		w.f = file

+		w.currentSize = 0

 		w.notifyRotate.Publish(struct{}{})

 	}