Tiny optimization for handling string output from server console

environment/docker/container.go

@@ -296,9 +296,20 @@ func (e *Environment) followOutput() error {
 		defer reader.Close()
 
 		r := bufio.NewReader(reader)
+
+		// Micro-optimization to create these replacements one time when this routine
+		// fires up, rather than on every line that is executed.
+		cr := []byte(" \r")
+		crr := []byte("\r\n")
+
+
+		// Avoid constantly re-allocating memory when we're flooding lines through this
+		// function by using the same buffer for the duration of the call and just truncating
+		// the value back to 0 every loop.
+		var str strings.Builder
 	ParentLoop:
 		for {
-			var b bytes.Buffer
+			str.Reset()
 			var line []byte
 			var isPrefix bool
 
@@ -310,7 +321,7 @@ func (e *Environment) followOutput() error {
 				// in line with that it thinks is the terminal size. Those returns break a lot of output handling,
 				// so we'll just replace them with proper new-lines and then split it later and send each line as
 				// its own event in the response.
-				b.Write(bytes.ReplaceAll(line, []byte(" \r"), []byte("\r\n")))
+				str.Write(bytes.Replace(line, cr, crr, -1))
 
 				// Finish this loop and begin outputting the line if there is no prefix (the line fit into
 				// the default buffer), or if we hit the end of the line.
@@ -327,7 +338,7 @@ func (e *Environment) followOutput() error {
 
 			// Publish the line for this loop. Break on new-line characters so every line is sent as a single
 			// output event, otherwise you get funky handling in the browser console.
-			for _, line := range strings.Split(b.String(), "\r\n") {
+			for _, line := range strings.Split(str.String(), "\r\n") {
 				e.Events().Publish(environment.ConsoleOutputEvent, line)
 			}