gob: add UpdateMemStats calls to malloc counter

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4808071

src/pkg/gob/encode.go

@@ -484,7 +484,7 @@ func isZero(val reflect.Value) bool {
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		return val.Uint() == 0
 	}
-	panic("unknown type in isZero" + val.Type().String())
+	panic("unknown type in isZero " + val.Type().String())
 }
 
 // encGobEncoder encodes a value that implements the GobEncoder interface.

src/pkg/gob/timing_test.go

@@ -53,6 +53,7 @@ func TestCountEncodeMallocs(t *testing.T) {
 	var buf bytes.Buffer
 	enc := NewEncoder(&buf)
 	bench := &Bench{7, 3.2, "now is the time", []byte("for all good men")}
+	runtime.UpdateMemStats()
 	mallocs := 0 - runtime.MemStats.Mallocs
 	const count = 1000
 	for i := 0; i < count; i++ {
@@ -61,6 +62,7 @@ func TestCountEncodeMallocs(t *testing.T) {
 			t.Fatal("encode:", err)
 		}
 	}
+	runtime.UpdateMemStats()
 	mallocs += runtime.MemStats.Mallocs
 	fmt.Printf("mallocs per encode of type Bench: %d\n", mallocs/count)
 }
@@ -77,6 +79,7 @@ func TestCountDecodeMallocs(t *testing.T) {
 		}
 	}
 	dec := NewDecoder(&buf)
+	runtime.UpdateMemStats()
 	mallocs := 0 - runtime.MemStats.Mallocs
 	for i := 0; i < count; i++ {
 		*bench = Bench{}
@@ -85,6 +88,7 @@ func TestCountDecodeMallocs(t *testing.T) {
 			t.Fatal("decode:", err)
 		}
 	}
+	runtime.UpdateMemStats()
 	mallocs += runtime.MemStats.Mallocs
 	fmt.Printf("mallocs per decode of type Bench: %d\n", mallocs/count)
 }