From b349cd2b0ad12c2ebe67ca2c6c1aa01bc9991520 Mon Sep 17 00:00:00 2001 From: Rob Pike Date: Fri, 2 Sep 2011 11:47:15 +1000 Subject: [PATCH] fmt/fmt_test.go: count mallocs in a few more cases. Interesting that Fprintf can do zero mallocs. (Sprintf must allocate the returned string.) R=golang-dev, bradfitz CC=golang-dev https://golang.org/cl/4977049 --- src/pkg/fmt/fmt_test.go | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go index 1142c9f8ad7..b1ad345186f 100644 --- a/src/pkg/fmt/fmt_test.go +++ b/src/pkg/fmt/fmt_test.go @@ -5,6 +5,7 @@ package fmt_test import ( + "bytes" . "fmt" "io" "math" @@ -503,12 +504,39 @@ func TestCountMallocs(t *testing.T) { Printf("mallocs per Sprintf(\"%%x\"): %d\n", mallocs/100) runtime.UpdateMemStats() mallocs = 0 - runtime.MemStats.Mallocs + for i := 0; i < 100; i++ { + Sprintf("%s", "hello") + } + runtime.UpdateMemStats() + mallocs += runtime.MemStats.Mallocs + Printf("mallocs per Sprintf(\"%%s\"): %d\n", mallocs/100) + runtime.UpdateMemStats() + mallocs = 0 - runtime.MemStats.Mallocs for i := 0; i < 100; i++ { Sprintf("%x %x", i, i) } runtime.UpdateMemStats() mallocs += runtime.MemStats.Mallocs Printf("mallocs per Sprintf(\"%%x %%x\"): %d\n", mallocs/100) + buf := new(bytes.Buffer) + runtime.UpdateMemStats() + mallocs = 0 - runtime.MemStats.Mallocs + for i := 0; i < 100; i++ { + buf.Reset() + Fprintf(buf, "%x %x %x", i, i, i) + } + runtime.UpdateMemStats() + mallocs += runtime.MemStats.Mallocs + Printf("mallocs per Fprintf(buf, \"%%x %%x %%x\"): %d\n", mallocs/100) + runtime.UpdateMemStats() + mallocs = 0 - runtime.MemStats.Mallocs + for i := 0; i < 100; i++ { + buf.Reset() + Fprintf(buf, "%s", "hello") + } + runtime.UpdateMemStats() + mallocs += runtime.MemStats.Mallocs + Printf("mallocs per Fprintf(buf, \"%%s\"): %d\n", mallocs/100) } type flagPrinter struct{}