Increase publish performance of small message ~500%

channel.go

@@ -229,21 +229,18 @@ func (ch *Channel) sendOpen(msg message) (err error) {
 		} else {
 			size = len(body)
 		}
+		var frames [3]frame
 
-		if err = ch.connection.send(&methodFrame{
+		frames[0] = &methodFrame{
 			ChannelId: ch.id,
 			Method:    content,
-		}); err != nil {
-			return
 		}
 
-		if err = ch.connection.send(&headerFrame{
+		frames[1] = &headerFrame{
 			ChannelId:  ch.id,
 			ClassId:    class,
 			Size:       uint64(len(body)),
 			Properties: props,
-		}); err != nil {
-			return
 		}
 
 		// chunk body into size (max frame size - frame header size)
@@ -252,11 +249,22 @@ func (ch *Channel) sendOpen(msg message) (err error) {
 				j = len(body)
 			}
 
-			if err = ch.connection.send(&bodyFrame{
-				ChannelId: ch.id,
-				Body:      body[i:j],
-			}); err != nil {
-				return
+			// Send first body frame together with the publish and header frame
+			if i == 0 {
+				frames[2] = &bodyFrame{
+					ChannelId: ch.id,
+					Body:      body[i:j],
+				}
+				if err = ch.connection.sendFrames(frames); err != nil {
+					return
+				}
+			} else {
+				if err = ch.connection.send(&bodyFrame{
+					ChannelId: ch.id,
+					Body:      body[i:j],
+				}); err != nil {
+					return
+				}
 			}
 		}
 	} else {

connection.go

@@ -189,6 +189,7 @@ func DialConfig(url string, config Config) (*Connection, error) {
 	if err != nil {
 		return nil, err
 	}
+	conn.(*net.TCPConn).SetNoDelay(false)
 
 	if uri.Scheme == "amqps" {
 		if config.TLSClientConfig == nil {
@@ -383,6 +384,34 @@ func (c *Connection) send(f frame) error {
 	return err
 }
 
+func (c *Connection) sendFrames(frames [3]frame) error {
+	if c.IsClosed() {
+		return ErrClosed
+	}
+
+	c.sendM.Lock()
+	err := c.writer.WriteFrames(frames)
+	c.sendM.Unlock()
+
+	if err != nil {
+		// shutdown could be re-entrant from signaling notify chans
+		go c.shutdown(&Error{
+			Code:   FrameError,
+			Reason: err.Error(),
+		})
+	} else {
+		// Broadcast we sent a frame, reducing heartbeats, only
+		// if there is something that can receive - like a non-reentrant
+		// call or if the heartbeater isn't running
+		select {
+		case c.sends <- time.Now():
+		default:
+		}
+	}
+
+	return err
+}
+
 func (c *Connection) shutdown(err *Error) {
 	atomic.StoreInt32(&c.closed, 1)
 

write.go

@@ -27,6 +27,20 @@ func (w *writer) WriteFrame(frame frame) (err error) {
 	return
 }
 
+func (w *writer) WriteFrames(frames [3]frame) (err error) {
+	for _, frame := range frames {
+		if err = frame.write(w.w); err != nil {
+			return
+		}
+	}
+
+	if buf, ok := w.w.(*bufio.Writer); ok {
+		err = buf.Flush()
+	}
+
+	return
+}
+
 func (f *methodFrame) write(w io.Writer) (err error) {
 	var payload bytes.Buffer