ULC UX not working under Linux(RH8.6 + WinCCOA 3.18 P012)

[alex.ranac]

Hi,

The ULC UX browser connection is not displaying the login screen when project running under Linux Redhat8.6 and WinCC OA 3.18 patch 12 (same for patch 11 and 10).

In the LogViewer when adding "-dbg http" to the webclient control manager the last line is:

WCCOActrl2:WCCOActrl (2), 2022.08.30 12:18:25.429, HTTP, successfully started websocket ui: "/opt/WinCC_OA/3.18/bin/WCCOAui -p vision/login.pnl -centered -iconBar -menuBar -lang en_US.utf8 client_ip ::ffff:A.A.A.A client_ua \"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.5112.102 Safari/537.36 Edg/104.0.1293.70\" -proj WEB"
WCCOActrl2:ulc: create PlatformScreen QSize(1490, 722)

3.18 Patch 004 with Redhat 8.4 works fine.

Any ideas?

Thank you!

[alex.ranac]

Hi,

After some troubleshooting I found that from 3.18 P010 to P12, there is a kernel compatibility issue with RedHat 8.6
As stated in the 3.18-P012 help the supported Redhat version is 8.5.
Indeed after changing to kernel-4.18.0-348.23.1.el8_5.x86_64 the issue was resolved.


Using top, perf top and ps afx i could see that the Ui manager for a ULC session launched by the webclient_http control manager was using 100% CPU and was generating a lot of g_mutex_lock and g_mutex_unlock events and also not going forward to launch the 2 qt zygote processes associated.

Strangely an UI launched from the console was working correctly.