Citrix XenApp: Limiting Application Instances

By default, XenApp does not limit the number of instances of a published application that can run at one time in a farm. By default, a user can launch more than one instance of a published application at the same time.

You can specify the maximum number of instances that a published application can run at one time or concurrently in the server farm. For example, you can publish an application and set a limit of 30 concurrent instances in the farm. Once 30 users are running the application at the same time, no more users can launch the application because the limit of 30 concurrent instances was reached.

Another connection control option lets you prevent any user from running multiple instances of a particular published application. With some applications, running more than one instance in a single user context can cause errors.

You can apply application limits independently to each published application. For example, you can apply the limitations on total concurrent instances and multiple instances by a single user to one published application. You can limit only the total concurrent instances of another application. You can configure a third application to limit launching of multiple instances by individual users.

Note: Connection control options apply to published applications and published desktops only and do not affect published content such as documents and media files that execute on the client device.

To specify a limit for a published application or desktop

1. Depending on the version of XenApp you have installed, from the Start menu, select All Programs > Citrix > Management Consoles and choose Access Management Console or Delivery Services Console.
2. In the left pane, select Citrix Resources > XenApp > yourfarmname > Applications and select the published application or desktop you want to modify.
3. From the Actions menu, select Modify application properties > Modify all properties.
4. In the Properties tree, select Limits.
5. On the Limits page, select one or both of these options:
   • Limit instances allowed to run in server farm. Select this option and enter the maximum number of instances that can run at one time in the server farm without regard to who launches the application.

     For example, if you type 10 in Maximum instances and a user tries to launch the application when 10 instances are running, the server denies the connection request and records the time and the name of the published application in the System log.

   • Allow only one instance of application for each user. Select this option to prevent any user from running more than one instance of this application at the same time.

Screenshot where you can change this setting per application:

Reference: Citrix Product Documentation: Limiting Application Instances