Product Documentation

Manage sessions through Delivery Groups

May 11, 2015

In addition to the procedures below, see the Session management article for information about session reliability, session roaming, auto client reconnect, ICA keep-alive, and workspace control.

Log off or disconnect a session, or send a message to users

  1. Select Delivery Groups in the Studio navigation pane.
  2. Select a group and then select View Machines in the Actions pane.
  3. To log a user off a session, select the session or desktop and select Log off in the Actions pane. The session closes and the machine becomes available to other users, unless it is allocated to a specific user.
  4. To disconnect a session, select the session or desktop, and select Disconnect in the Actions pane. Applications continue to run and the machine remains allocated to that user. The user can reconnect to the same machine.
  5. To send a message to users, select the session, machine, or user, and then select Send message in the Actions pane. Enter the message.

You can configure power state timers for Desktop OS machines to automatically handle unused sessions. See the Power manage machines section in the Manage machines in a Delivery Group article for details.

Configure session prelaunch and session linger

These features are supported on Server OS machines only.

The session prelaunch and session linger features help specified users access applications quickly, by starting sessions before they are requested (session prelaunch) and keeping application sessions active after a user closes all applications (session linger).

By default, session prelaunch and session linger are not used: a session starts (launches) when a user starts an application, and remains active until the last open application in the session closes.

Considerations:

  • The Delivery Group must support applications, and the machines must be running a VDA for Windows Server OS, minimum version 7.6.
  • These features are supported only when using Citrix Receiver for Windows, and also require additional Citrix Receiver configuration. For instructions, search for session prelaunch in the product documentation for your Citrix Receiver for Windows version.
  • Note that Citrix Receiver for HTML5 is not supported.
  • When using session prelaunch, if a user's machine is put into "suspend" or "hibernate" mode, prelaunch will not work (regardless of session prelaunch settings). Users can lock their machines/sessions, but if a user logs off from Citrix Receiver, the session is ended and prelaunch no longer applies.
  • When using session prelaunch, physical client machines cannot use the suspend or hibernate power management functions. Client machine users can lock their sessions but should not log off.
  • Prelaunched and lingering sessions consume a license, but only when connected. Unused prelaunched and lingering sessions disconnect after 15 minutes by default. This value can be configured in PowerShell (New/Set-BrokerSessionPreLaunch cmdlet).
  • Careful planning and monitoring of your users’ activity patterns are essential to tailoring these features to complement each other. Optimal configuration balances the benefits of earlier application availability for users against the cost of keeping licenses in use and resources allocated.
  • You can also configure session prelaunch for a scheduled time of day in Citrix Receiver.

How long unused prelaunched and lingering sessions remain active

There are several ways to specify how long an unused session remains active if the user does not start an application: a configured timeout and server load thresholds. You can configure all of them; the event that occurs first will cause the unused session to end.

  • Timeout: A configured timeout specifies the number of minutes, hours, or days an unused prelaunched or lingering session remains active. If you configure too short a timeout, prelaunched sessions will end before they provide the user benefit of quicker application access. If you configure too long a timeout, incoming user connections might be denied because the server doesn't have enough resources.

You cannot disable this timeout from Studio, but you can in the SDK (New/Set-BrokerSessionPreLaunch cmdlet). If you disable the timeout, it will not appear in the Studio display for that Delivery Group or in the Edit Delivery Group wizard.

  • Thresholds: Automatically ending prelaunched and lingering sessions based on server load ensures that sessions remain open as long as possible, assuming server resources are available. Unused prelaunched and lingering sessions will not cause denied connections because they will be ended automatically when resources are needed for new user sessions.

You can configure two thresholds: the average percentage load of all servers in the Delivery Group, and the maximum percentage load of a single server in the Delivery Group. When a threshold is exceeded, the sessions that have been in the prelaunch or lingering state for the longest time are ended, sessions are ended one-by-one at minute intervals until the load falls below the threshold. (While the threshold is exceeded, no new prelaunch sessions are started.)

Servers with VDAs that have not registered with the Controller and servers in maintenance mode are considered fully loaded. An unplanned outage will cause prelaunch and lingering sessions to be ended automatically to free capacity.

To enable session prelaunch

  1. Select Delivery Groups in the Studio navigation pane.
  2. Select a Delivery Group, and then click Edit Delivery Group in the Actions pane.
  3. On the Application Prelaunch page, enable session prelaunch by choosing when sessions should launch:
    • When a user starts an application. This is the default setting; session prelaunch is disabled.
    • When any user in the Delivery Group logs on to Citrix Receiver for Windows.
    • When anyone in a list of users and user groups logs on to Citrix Receiver for Windows. Be sure to also specify users or user groups if you choose this option.


  4. A prelaunched session is replaced with a regular session when the user starts an application. If the user does not start an application (the prelaunched session is unused), the following settings affect how long that session remains active. 
    • When a specified time interval elapses. You can change the time interval (1-99 days, 1-2376 hours, or 1-142,560 minutes).
    • When the average load on all machines in the Delivery Group exceeds a specified percentage (1-99%).
    • When the load on any machine in the Delivery Group exceeds a specified percentage (1-99%).

    Recap: A prelaunched session remains active until one of the following events occurs: a user starts an application, the specified time elapses, or a specified load threshold is exceeded.

To enable session linger

  1. Select Delivery Groups in the Studio navigation pane.
  2. Select a Delivery Group, and then click Edit Delivery Group in the Actions pane.
  3. On the Application Lingering page, enable session linger by selecting the Keep sessions active until radio button.


  4. Several settings affect how long a lingering session remains active if the user does not start another application. 
    • When a specified time interval elapses. You can change the time interval (1-99 days, 1-2376 hours, or 1-142,560 minutes).
    • When the average load on all machines in the Delivery Group exceeds a specified percentage (1-99%).
    • When the load on any machine in the Delivery Group exceeds a specified percentage (1-99%).

    Recap: A lingering session remains active until one of the following events occurs: a user starts an application, the specified time elapses, or a specified load threshold is exceeded.