net/http: add a known goroutine, don't check goroutine leaks in benchmark mode

Change-Id: I8aa070f8093e80ba19f0546d7447caf847a2b388
Reviewed-on: https://go-review.googlesource.com/45912
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/http/main_test.go

@@ -37,6 +37,7 @@ func interestingGoroutines() (gs []string) {
 		}
 		stack := strings.TrimSpace(sl[1])
 		if stack == "" ||
+			strings.Contains(stack, "os/signal.signal_recv") ||
 			strings.Contains(stack, "created by net.startServer") ||
 			strings.Contains(stack, "created by testing.RunTests") ||
 			strings.Contains(stack, "closeWriteAndWait") ||
@@ -56,8 +57,9 @@ func interestingGoroutines() (gs []string) {
 
 // Verify the other tests didn't leave any goroutines running.
 func goroutineLeaked() bool {
-	if testing.Short() {
+	if testing.Short() || runningBenchmarks() {
-		// not counting goroutines for leakage in -short mode
+		// Don't worry about goroutine leaks in -short mode or in
+		// benchmark mode. Too distracting when there are false positives.
 		return false
 	}
 
@@ -92,6 +94,18 @@ func setParallel(t *testing.T) {
 	}
 }
 
+func runningBenchmarks() bool {
+	for i, arg := range os.Args {
+		if strings.HasPrefix(arg, "-test.bench=") && !strings.HasSuffix(arg, "=") {
+			return true
+		}
+		if arg == "-test.bench" && i < len(os.Args)-1 && os.Args[i+1] != "" {
+			return true
+		}
+	}
+	return false
+}
+
 func afterTest(t testing.TB) {
 	http.DefaultTransport.(*http.Transport).CloseIdleConnections()
 	if testing.Short() {