fix: keep load test websocket sessions alive

loadtest/im-pressure/wsclient.go

@@ -116,6 +116,12 @@ func connectWSClient(ctx context.Context, cfg *Config, account AccountRecord, ap
 		return nil, fmt.Errorf("login %s: %w", account.Username, err)
 	}
 	client.applyLogin(ctrl)
+	pingInterval, err := configDuration(cfg.WSPingInterval)
+	if err != nil {
+		client.Close()
+		return nil, err
+	}
+	client.startKeepalive(pingInterval)
 	return client, nil
 }
 
@@ -369,6 +375,37 @@ func (c *WSClient) readLoop() {
 	}
 }
 
+func (c *WSClient) startKeepalive(interval time.Duration) {
+	go func() {
+		ticker := time.NewTicker(interval)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-ticker.C:
+				deadline := time.Now().Add(interval / 2)
+				if err := c.conn.WriteControl(websocket.PingMessage, nil, deadline); err != nil {
+					_ = c.conn.Close()
+					return
+				}
+			case <-c.done:
+				return
+			}
+		}
+	}()
+}
+
+func (c *WSClient) alive() bool {
+	if c == nil || c.closed.Load() {
+		return false
+	}
+	select {
+	case <-c.done:
+		return false
+	default:
+		return true
+	}
+}
+
 func (c *WSClient) Close() {
 	if c == nil || !c.closed.CompareAndSwap(false, true) {
 		return