net/http: add disabled test for Body Read/Close lock granularity

Update #7121

R=golang-codereviews, gobot, dsymonds
CC=golang-codereviews
https://golang.org/cl/51750044

src/pkg/net/http/serve_test.go

@@ -2148,6 +2148,57 @@ func TestTransportAndServerSharedBodyRace(t *testing.T) {
 	(<-backendRespc).Body.Close()
 }
 
+// Test that a hanging Request.Body.Read from another goroutine can't
+// cause the Handler goroutine's Request.Body.Close to block.
+func TestRequestBodyCloseDoesntBlock(t *testing.T) {
+	t.Skipf("Skipping known issue; see golang.org/issue/7121")
+	if testing.Short() {
+		t.Skip("skipping in -short mode")
+	}
+	defer afterTest(t)
+
+	readErrCh := make(chan error, 1)
+	errCh := make(chan error, 2)
+
+	server := httptest.NewServer(HandlerFunc(func(rw ResponseWriter, req *Request) {
+		go func(body io.Reader) {
+			_, err := body.Read(make([]byte, 100))
+			readErrCh <- err
+		}(req.Body)
+		time.Sleep(500 * time.Millisecond)
+	}))
+	defer server.Close()
+
+	closeConn := make(chan bool)
+	defer close(closeConn)
+	go func() {
+		conn, err := net.Dial("tcp", server.Listener.Addr().String())
+		if err != nil {
+			errCh <- err
+			return
+		}
+		defer conn.Close()
+		_, err = conn.Write([]byte("POST / HTTP/1.1\r\nConnection: close\r\nHost: foo\r\nContent-Length: 100000\r\n\r\n"))
+		if err != nil {
+			errCh <- err
+			return
+		}
+		// And now just block, making the server block on our
+		// 100000 bytes of body that will never arrive.
+		<-closeConn
+	}()
+	select {
+	case err := <-readErrCh:
+		if err == nil {
+			t.Error("Read was nil. Expected error.")
+		}
+	case err := <-errCh:
+		t.Error(err)
+	case <-time.After(5 * time.Second):
+		t.Error("timeout")
+	}
+}
+
 func TestResponseWriterWriteStringAllocs(t *testing.T) {
 	ht := newHandlerTest(HandlerFunc(func(w ResponseWriter, r *Request) {
 		if r.URL.Path == "/s" {