Distributing Virtual Users Over Multiple Windows Sessions

Windows operating systems do not dedicate all available resources to a single Windows session. For load testing with UI-based technologies such as browser-driven web or SAPGUI, Silk Performer allows you to distribute virtual users over several Windows sessions. This allows you to make better use from resources of powerful hardware. Virtual users that execute Java or .NetFramework code that is not designed to run in multiple instances can be spread over several Windows sessions.

Unlike with GUI-level testing, where each virtual user creates its own Windows session, this setting allows you to run more than one virtual user within a session. How many sessions an agent machine can handle depends on its hardware resources, in particular on the CPU and memory. This setting is available for the following technologies: browser-driven web, Citrix, SAPGUI, Java Framework.

  1. In the Silk Performer menu, click Settings > System .
  2. Click the Agents icon and the Advanced tab.
  3. Enable Create multiple sessions.
  4. Specify the Maximum sessions Silk Performer is allowed to create.
  5. In the fields Username and Password, specify the credentials for the Windows sessions that are to be created.
  6. Click OK to save your settings.
When you start a load test, Silk Performer creates multiple Windows sessions, logs in to the sessions using the credentials, and starts virtual users within the sessions.
Note: When you enable this setting, make sure that your agent machines are set up identically. Also, the agent machines must be equipped with the Remote Desktop Services (RDS) with appropriately set up licensing options. The Windows sessions are opened locally from within the Remote Desktop Services host. Thus, per device licenses are better suited, although per user licenses work as well.
Tip: The number of virtual users you can run on an agent machine can be read from the agent's capabilities. These default capabilities are calculated based on the CPU and memory. However, a realistic number for your specific environment and conditions can only be determined if the user types (the script and settings) are taken into account. The Evaluate Agent VUser Capacity dialog helps you to determine a good maximum number of virtual users for a particular agent and user type. For more information, read Evaluating Agent VUser Capacity.