Add /stacksz to monitoring

Allows to get the server's stacks from the monitoring interface.

server/monitor.go

@@ -352,6 +352,26 @@ func (s *Server) HandleSubsz(w http.ResponseWriter, r *http.Request) {
 	ResponseHandler(w, r, b)
 }
 
+// HandleStacksz processes HTTP requests for getting stacks
+func (s *Server) HandleStacksz(w http.ResponseWriter, r *http.Request) {
+	// Do not get any lock here that would prevent gettign the stacks
+	// if we were to have a deadlock somewhere.
+	var buf []byte
+	size := 10000
+	n := 0
+	for {
+		buf = make([]byte, size)
+		n = runtime.Stack(buf, true)
+		if n < size {
+			break
+		}
+
+		size = 2 * size
+	}
+	// Handle response
+	ResponseHandler(w, r, buf[:n])
+}
+
 // Varz will output server information on the monitoring port at /varz.
 type Varz struct {
 	*Info

server/monitor_test.go

@@ -1206,3 +1206,41 @@ func createClientConnWithName(t *testing.T, name string) *nats.Conn {
 
 	return nc
 }
+
+func TestStacksz(t *testing.T) {
+	s := runMonitorServer()
+	defer s.Shutdown()
+
+	url := fmt.Sprintf("http://localhost:%d/", MONITOR_PORT)
+	resp, err := http.Get(url + "stacksz")
+	if err != nil {
+		t.Fatalf("Expected no error: Got %v\n", err)
+	}
+	if resp.StatusCode != 200 {
+		t.Fatalf("Expected a 200 response, got %d\n", resp.StatusCode)
+	}
+	ct := resp.Header.Get("Content-Type")
+	if ct != "application/json" {
+		t.Fatalf("Expected application/json content-type, got %s\n", ct)
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatalf("Got an error reading the body: %v\n", err)
+	}
+	// Check content
+	str := string(body)
+	if !strings.Contains(str, "HandleStacksz") {
+		t.Fatalf("Result does not seem to contain server's stacks:\n%v", str)
+	}
+	// Test JSONP
+	respj, errj := http.Get(fmt.Sprintf("http://localhost:%d/", MONITOR_PORT) + "subscriptionsz?callback=callback")
+	ct = respj.Header.Get("Content-Type")
+	if errj != nil {
+		t.Fatalf("Expected no error: Got %v\n", err)
+	}
+	if ct != "application/javascript" {
+		t.Fatalf("Expected application/javascript content-type, got %s\n", ct)
+	}
+	defer respj.Body.Close()
+}

server/server.go

@@ -422,11 +422,12 @@ func (s *Server) StartHTTPSMonitoring() {
 
 // HTTP endpoints
 const (
-	RootPath   = "/"
-	VarzPath   = "/varz"
-	ConnzPath  = "/connz"
-	RoutezPath = "/routez"
-	SubszPath  = "/subsz"
+	RootPath    = "/"
+	VarzPath    = "/varz"
+	ConnzPath   = "/connz"
+	RoutezPath  = "/routez"
+	SubszPath   = "/subsz"
+	StackszPath = "/stacksz"
 )
 
 // Start the monitoring server
@@ -476,6 +477,8 @@ func (s *Server) startMonitoring(secure bool) {
 	mux.HandleFunc(SubszPath, s.HandleSubsz)
 	// Subz alias for backwards compatibility
 	mux.HandleFunc("/subscriptionsz", s.HandleSubsz)
+	// Stacksz
+	mux.HandleFunc(StackszPath, s.HandleStacksz)
 
 	srv := &http.Server{
 		Addr:           hp,