all: set GOMAXPROCS to 1 when counting mallocs

also fix an annoying test that relies on $GOROOT be set.
Fixes #3690.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6844086

src/pkg/encoding/gob/timing_test.go

@@ -50,6 +50,7 @@ func BenchmarkEndToEndByteBuffer(b *testing.B) {
 }
 
 func TestCountEncodeMallocs(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	var buf bytes.Buffer
 	enc := NewEncoder(&buf)
 	bench := &Bench{7, 3.2, "now is the time", []byte("for all good men")}
@@ -69,6 +70,7 @@ func TestCountEncodeMallocs(t *testing.T) {
 }
 
 func TestCountDecodeMallocs(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	var buf bytes.Buffer
 	enc := NewEncoder(&buf)
 	bench := &Bench{7, 3.2, "now is the time", []byte("for all good men")}

src/pkg/fmt/fmt_test.go

@@ -581,6 +581,7 @@ var mallocTest = []struct {
 var _ bytes.Buffer
 
 func TestCountMallocs(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	for _, mt := range mallocTest {
 		const N = 100
 		memstats := new(runtime.MemStats)

src/pkg/math/big/nat_test.go

@@ -180,6 +180,7 @@ func allocBytes(f func()) uint64 {
 // does not cause deep recursion and in turn allocate too much memory.
 // Test case for issue 3807.
 func TestMulUnbalanced(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	x := rndNat(50000)
 	y := rndNat(40)
 	allocSize := allocBytes(func() {

src/pkg/net/http/header_test.go

@@ -188,6 +188,7 @@ type errorfer interface {
 }
 
 func doHeaderWriteSubset(n int, t errorfer) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	h := Header(map[string][]string{
 		"Content-Length": {"123"},
 		"Content-Type":   {"text/plain"},
@@ -204,7 +205,7 @@ func doHeaderWriteSubset(n int, t errorfer) {
 	var m1 runtime.MemStats
 	runtime.ReadMemStats(&m1)
 	if mallocs := m1.Mallocs - m0.Mallocs; n >= 100 && mallocs >= uint64(n) {
-		// TODO(bradfitz,rsc): once we can sort with allocating,
+		// TODO(bradfitz,rsc): once we can sort without allocating,
 		// make this an error.  See http://golang.org/issue/3761
 		// t.Errorf("did %d mallocs (>= %d iterations); should have avoided mallocs", mallocs, n)
 	}

src/pkg/net/rpc/server_test.go

@@ -446,6 +446,7 @@ func dialHTTP() (*Client, error) {
 }
 
 func countMallocs(dial func() (*Client, error), t *testing.T) uint64 {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	once.Do(startServer)
 	client, err := dial()
 	if err != nil {

src/pkg/path/filepath/path_test.go

@@ -91,6 +91,7 @@ var wincleantests = []PathTest{
 }
 
 func TestClean(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	tests := cleantests
 	if runtime.GOOS == "windows" {
 		for i := range tests {
@@ -897,7 +898,7 @@ func TestDriveLetterInEvalSymlinks(t *testing.T) {
 }
 
 func TestBug3486(t *testing.T) { // http://code.google.com/p/go/issues/detail?id=3486
-	root, err := filepath.EvalSymlinks(os.Getenv("GOROOT"))
+	root, err := filepath.EvalSymlinks(runtime.GOROOT())
 	if err != nil {
 		t.Fatal(err)
 	}

src/pkg/path/path_test.go

@@ -64,6 +64,7 @@ var cleantests = []PathTest{
 }
 
 func TestClean(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	for _, test := range cleantests {
 		if s := Clean(test.path); s != test.result {
 			t.Errorf("Clean(%q) = %q, want %q", test.path, s, test.result)

src/pkg/reflect/all_test.go

@@ -2012,6 +2012,7 @@ func TestAddr(t *testing.T) {
 }
 
 func noAlloc(t *testing.T, n int, f func(int)) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	// once to prime everything
 	f(-1)
 	memstats := new(runtime.MemStats)
@@ -2021,12 +2022,9 @@ func noAlloc(t *testing.T, n int, f func(int)) {
 	for j := 0; j < n; j++ {
 		f(j)
 	}
-	// A few allocs may happen in the testing package when GOMAXPROCS > 1, so don't
-	// require zero mallocs.
-	// A new thread, one of which will be created if GOMAXPROCS>1, does 6 allocations.
 	runtime.ReadMemStats(memstats)
 	mallocs := memstats.Mallocs - oldmallocs
-	if mallocs > 10 {
+	if mallocs > 0 {
 		t.Fatalf("%d mallocs after %d iterations", mallocs, n)
 	}
 }

src/pkg/runtime/gc_test.go

@@ -10,6 +10,7 @@ import (
 )
 
 func TestGcSys(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	memstats := new(runtime.MemStats)
 	runtime.GC()
 	runtime.ReadMemStats(memstats)

src/pkg/runtime/mallocrep1.go

@@ -39,6 +39,7 @@ func OkAmount(size, n uintptr) bool {
 }
 
 func AllocAndFree(size, count int) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	if *chatty {
 		fmt.Printf("size=%d count=%d ...\n", size, count)
 	}

src/pkg/strconv/strconv_test.go

@@ -44,6 +44,7 @@ var (
 )
 
 func TestCountMallocs(t *testing.T) {
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 	for _, mt := range mallocTest {
 		const N = 100
 		memstats := new(runtime.MemStats)