fmt: use RunParallel in benchmarks

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/67910046

diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index 7237a6fca2bbe4c80a1a45728c4dc93345ecffb2..14a1a56c0458bde9e73c0e055c5738b2f8df1dfa 100644 (file)
--- a/src/pkg/fmt/fmt_test.go
+++ b/src/pkg/fmt/fmt_test.go
@@ -11,7 +11,6 @@ import (
        "math"
        "runtime"
        "strings"
-       "sync/atomic"
        "testing"
        "time"
        "unicode"
@@ -634,69 +633,63 @@ func TestReorder(t *testing.T) {
 }
 
 func BenchmarkSprintfEmpty(b *testing.B) {
-       benchmarkSprintf(b, func(buf *bytes.Buffer) {
-               Sprintf("")
+       b.RunParallel(func(pb *testing.PB) {
+               for pb.Next() {
+                       Sprintf("")
+               }
        })
 }
 
 func BenchmarkSprintfString(b *testing.B) {
-       benchmarkSprintf(b, func(buf *bytes.Buffer) {
-               Sprintf("%s", "hello")
+       b.RunParallel(func(pb *testing.PB) {
+               for pb.Next() {
+                       Sprintf("%s", "hello")
+               }
        })
 }
 
 func BenchmarkSprintfInt(b *testing.B) {
-       benchmarkSprintf(b, func(buf *bytes.Buffer) {
-               Sprintf("%d", 5)
+       b.RunParallel(func(pb *testing.PB) {
+               for pb.Next() {
+                       Sprintf("%d", 5)
+               }
        })
 }
 
 func BenchmarkSprintfIntInt(b *testing.B) {
-       benchmarkSprintf(b, func(buf *bytes.Buffer) {
-               Sprintf("%d %d", 5, 6)
+       b.RunParallel(func(pb *testing.PB) {
+               for pb.Next() {
+                       Sprintf("%d %d", 5, 6)
+               }
        })
 }
 
 func BenchmarkSprintfPrefixedInt(b *testing.B) {
-       benchmarkSprintf(b, func(buf *bytes.Buffer) {
-               Sprintf("This is some meaningless prefix text that needs to be scanned %d", 6)
+       b.RunParallel(func(pb *testing.PB) {
+               for pb.Next() {
+                       Sprintf("This is some meaningless prefix text that needs to be scanned %d", 6)
+               }
        })
 }
 
 func BenchmarkSprintfFloat(b *testing.B) {
-       benchmarkSprintf(b, func(buf *bytes.Buffer) {
-               Sprintf("%g", 5.23184)
+       b.RunParallel(func(pb *testing.PB) {
+               for pb.Next() {
+                       Sprintf("%g", 5.23184)
+               }
        })
 }
 
 func BenchmarkManyArgs(b *testing.B) {
-       benchmarkSprintf(b, func(buf *bytes.Buffer) {
-               buf.Reset()
-               Fprintf(buf, "%2d/%2d/%2d %d:%d:%d %s %s\n", 3, 4, 5, 11, 12, 13, "hello", "world")
+       b.RunParallel(func(pb *testing.PB) {
+               var buf bytes.Buffer
+               for pb.Next() {
+                       buf.Reset()
+                       Fprintf(&buf, "%2d/%2d/%2d %d:%d:%d %s %s\n", 3, 4, 5, 11, 12, 13, "hello", "world")
+               }
        })
 }
 
-func benchmarkSprintf(b *testing.B, f func(buf *bytes.Buffer)) {
-       const CallsPerSched = 1000
-       procs := runtime.GOMAXPROCS(-1)
-       N := int32(b.N / CallsPerSched)
-       c := make(chan bool, procs)
-       for p := 0; p < procs; p++ {
-               go func() {
-                       var buf bytes.Buffer
-                       for atomic.AddInt32(&N, -1) >= 0 {
-                               for g := 0; g < CallsPerSched; g++ {
-                                       f(&buf)
-                               }
-                       }
-                       c <- true
-               }()
-       }
-       for p := 0; p < procs; p++ {
-               <-c
-       }
-}
-
 var mallocBuf bytes.Buffer
 
 var mallocTest = []struct {