time: in Format give buffer an initial capacity
I have a small web server that simply sets several cookies
along with an expires header, and then returns. In the
cpuprofile for a 200k request benchmark, time.Time.Format()
was showing up as 8.3% of cpu usage. Giving the buffer an
inital capacity to avoid reallocs on append drops it down to
7.6%.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5992058
diff --git a/src/pkg/time/format.go b/src/pkg/time/format.go
index 98d4bb5..bb32bc8 100644
--- a/src/pkg/time/format.go
+++ b/src/pkg/time/format.go
@@ -367,7 +367,7 @@
hour int = -1
min int
sec int
- b buffer
+ b buffer = make([]byte, 0, len(layout))
)
// Each iteration generates one std value.
for {
