context: attempt to deflake timing tests

Passes on OpenBSD now when running it with -count=500.

Presumably this will also fix the same problems seen on FreeBSD and
Windows.

Fixes #15158

Change-Id: I86451c901613dfa5ecff0c2ecc516527a3c011b3
Reviewed-on: https://go-review.googlesource.com/21840
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

2 files changed, 30 insertions, 39 deletions

diff --git a/src/context/context_test.go b/src/context/context_test.go
index 0616704dd8..aa26161d2b 100644
--- a/src/context/context_test.go
+++ b/src/context/context_test.go
@@ -6,7 +6,6 @@ package context
 
 import (
 	"fmt"
-	"internal/testenv"
 	"math/rand"
 	"runtime"
 	"strings"
@@ -230,64 +229,55 @@ func TestChildFinishesFirst(t *testing.T) {
 	}
 }
 
-func testDeadline(c Context, wait time.Duration, t *testing.T) {
+func testDeadline(c Context, name string, failAfter time.Duration, t *testing.T) {
 	select {
-	case <-time.After(wait):
-		t.Fatalf("context should have timed out")
+	case <-time.After(failAfter):
+		t.Fatalf("%s: context should have timed out", name)
 	case <-c.Done():
 	}
 	if e := c.Err(); e != DeadlineExceeded {
-		t.Errorf("c.Err() == %v want %v", e, DeadlineExceeded)
+		t.Errorf("%s: c.Err() == %v; want %v", name, e, DeadlineExceeded)
 	}
 }
 
 func TestDeadline(t *testing.T) {
-	if runtime.GOOS == "openbsd" {
-		testenv.SkipFlaky(t, 15158)
-	}
-	c, _ := WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
+	c, _ := WithDeadline(Background(), time.Now().Add(50*time.Millisecond))
 	if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
 		t.Errorf("c.String() = %q want prefix %q", got, prefix)
 	}
-	testDeadline(c, 200*time.Millisecond, t)
+	testDeadline(c, "WithDeadline", time.Second, t)
 
-	c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
+	c, _ = WithDeadline(Background(), time.Now().Add(50*time.Millisecond))
 	o := otherContext{c}
-	testDeadline(o, 200*time.Millisecond, t)
+	testDeadline(o, "WithDeadline+otherContext", time.Second, t)
 
-	c, _ = WithDeadline(Background(), time.Now().Add(100*time.Millisecond))
+	c, _ = WithDeadline(Background(), time.Now().Add(50*time.Millisecond))
 	o = otherContext{c}
-	c, _ = WithDeadline(o, time.Now().Add(300*time.Millisecond))
-	testDeadline(c, 200*time.Millisecond, t)
+	c, _ = WithDeadline(o, time.Now().Add(4*time.Second))
+	testDeadline(c, "WithDeadline+otherContext+WithDeadline", 2*time.Second, t)
 }
 
 func TestTimeout(t *testing.T) {
-	if runtime.GOOS == "openbsd" {
-		testenv.SkipFlaky(t, 15158)
-	}
-	c, _ := WithTimeout(Background(), 100*time.Millisecond)
+	c, _ := WithTimeout(Background(), 50*time.Millisecond)
 	if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
 		t.Errorf("c.String() = %q want prefix %q", got, prefix)
 	}
-	testDeadline(c, 200*time.Millisecond, t)
+	testDeadline(c, "WithTimeout", time.Second, t)
 
-	c, _ = WithTimeout(Background(), 100*time.Millisecond)
+	c, _ = WithTimeout(Background(), 50*time.Millisecond)
 	o := otherContext{c}
-	testDeadline(o, 200*time.Millisecond, t)
+	testDeadline(o, "WithTimeout+otherContext", time.Second, t)
 
-	c, _ = WithTimeout(Background(), 100*time.Millisecond)
+	c, _ = WithTimeout(Background(), 50*time.Millisecond)
 	o = otherContext{c}
-	c, _ = WithTimeout(o, 300*time.Millisecond)
-	testDeadline(c, 200*time.Millisecond, t)
+	c, _ = WithTimeout(o, 3*time.Second)
+	testDeadline(c, "WithTimeout+otherContext+WithTimeout", 2*time.Second, t)
 }
 
 func TestCanceledTimeout(t *testing.T) {
-	if runtime.GOOS == "openbsd" {
-		testenv.SkipFlaky(t, 15158)
-	}
-	c, _ := WithTimeout(Background(), 200*time.Millisecond)
+	c, _ := WithTimeout(Background(), time.Second)
 	o := otherContext{c}
-	c, cancel := WithTimeout(o, 400*time.Millisecond)
+	c, cancel := WithTimeout(o, 2*time.Second)
 	cancel()
 	time.Sleep(100 * time.Millisecond) // let cancelation propagate
 	select {
@@ -398,9 +388,9 @@ func TestAllocs(t *testing.T) {
 			gccgoLimit: 8,
 		},
 		{
-			desc: "WithTimeout(bg, 100*time.Millisecond)",
+			desc: "WithTimeout(bg, 5*time.Millisecond)",
 			f: func() {
-				c, cancel := WithTimeout(bg, 100*time.Millisecond)
+				c, cancel := WithTimeout(bg, 5*time.Millisecond)
 				cancel()
 				<-c.Done()
 			},
@@ -414,7 +404,11 @@ func TestAllocs(t *testing.T) {
 			// TOOD(iant): Remove this when gccgo does do escape analysis.
 			limit = test.gccgoLimit
 		}
-		if n := testing.AllocsPerRun(100, test.f); n > limit {
+		numRuns := 100
+		if testing.Short() {
+			numRuns = 10
+		}
+		if n := testing.AllocsPerRun(numRuns, test.f); n > limit {
 			t.Errorf("%s allocs = %f want %d", test.desc, n, int(limit))
 		}
 	}
@@ -494,9 +488,6 @@ func TestLayersTimeout(t *testing.T) {
 }
 
 func testLayers(t *testing.T, seed int64, testTimeout bool) {
-	if runtime.GOOS == "openbsd" {
-		testenv.SkipFlaky(t, 15158)
-	}
 	rand.Seed(seed)
 	errorf := func(format string, a ...interface{}) {
 		t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
@@ -549,7 +540,7 @@ func testLayers(t *testing.T, seed int64, testTimeout bool) {
 	if testTimeout {
 		select {
 		case <-ctx.Done():
-		case <-time.After(timeout + 100*time.Millisecond):
+		case <-time.After(timeout + time.Second):
 			errorf("ctx should have timed out")
 		}
 		checkValues("after timeout")
diff --git a/src/context/withtimeout_test.go b/src/context/withtimeout_test.go
index 3ab6fc347f..2aea303bed 100644
--- a/src/context/withtimeout_test.go
+++ b/src/context/withtimeout_test.go
@@ -13,9 +13,9 @@ import (
 func ExampleWithTimeout() {
 	// Pass a context with a timeout to tell a blocking function that it
 	// should abandon its work after the timeout elapses.
-	ctx, _ := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	ctx, _ := context.WithTimeout(context.Background(), 50*time.Millisecond)
 	select {
-	case <-time.After(200 * time.Millisecond):
+	case <-time.After(1 * time.Second):
 		fmt.Println("overslept")
 	case <-ctx.Done():
 		fmt.Println(ctx.Err()) // prints "context deadline exceeded"