From 4d29c8608f5391a8b7032a621d12e8146aedab54 Mon Sep 17 00:00:00 2001
From: Wojciech Tyczynski <wojtekt@google.com>
Date: Thu, 18 May 2017 12:05:29 +0200
Subject: [PATCH] Avoid strings.Join which is expensive

---
 pkg/proxy/iptables/proxier.go | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/pkg/proxy/iptables/proxier.go b/pkg/proxy/iptables/proxier.go
index faee0d34f83..1eb90c5f8bb 100644
--- a/pkg/proxy/iptables/proxier.go
+++ b/pkg/proxy/iptables/proxier.go
@@ -1543,7 +1543,15 @@ func (proxier *Proxier) clearUDPConntrackForPort(port int) {
 
 // Join all words with spaces, terminate with newline and write to buf.
 func writeLine(buf *bytes.Buffer, words ...string) {
-	buf.WriteString(strings.Join(words, " ") + "\n")
+	// We avoid strings.Join for performance reasons.
+	for i := range words {
+		buf.WriteString(words[i])
+		if i < len(words)-1 {
+			buf.WriteByte(' ')
+		} else {
+			buf.WriteByte('\n')
+		}
+	}
 }
 
 func isLocalIP(ip string) (bool, error) {