add websocket client stress test, passed and update the vendors (this commit fixes the https://github.com/kataras/iris/issues/1178 and https://github.com/kataras/iris/issues/1173)

Former-commit-id: 74ccd8f4bf60a71f1eb0e34149a6f19de95a9148

_examples/websocket/go-client-stress-test/server/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"sync/atomic"
+	"time"
+
+	"github.com/kataras/iris"
+	"github.com/kataras/iris/websocket"
+)
+
+const totalClients = 1200
+
+func main() {
+	app := iris.New()
+
+	// websocket.Config{PingPeriod: ((60 * time.Second) * 9) / 10}
+	ws := websocket.New(websocket.Config{})
+	ws.OnConnection(handleConnection)
+	app.Get("/socket", ws.Handler())
+
+	go func() {
+		t := time.NewTicker(2 * time.Second)
+		for {
+			<-t.C
+
+			conns := ws.GetConnections()
+			for _, conn := range conns {
+				// fmt.Println(conn.ID())
+				// Do nothing.
+				_ = conn
+			}
+
+			if atomic.LoadUint64(&count) == totalClients {
+				fmt.Println("ALL CLIENTS DISCONNECTED SUCCESSFULLY.")
+				t.Stop()
+				os.Exit(0)
+				return
+			}
+		}
+	}()
+
+	app.Run(iris.Addr(":8080"))
+}
+
+func handleConnection(c websocket.Connection) {
+	c.OnError(func(err error) { handleErr(c, err) })
+	c.OnDisconnect(func() { handleDisconnect(c) })
+	c.On("chat", func(message string) {
+		c.To(websocket.Broadcast).Emit("chat", c.ID()+": "+message)
+	})
+}
+
+var count uint64
+
+func handleDisconnect(c websocket.Connection) {
+	atomic.AddUint64(&count, 1)
+	fmt.Printf("client [%s] disconnected!\n", c.ID())
+}
+
+func handleErr(c websocket.Connection, err error) {
+	fmt.Printf("client [%s] errored: %v\n", c.ID(), err)
+}