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# Distribute load generators

This topic describes the different types of load generators, and how to distribute them to groups in a performance test. It also describes how to assign elastic load generators to a test.

In this topic:

## About load generators

A load generator is a host machine on which Vusers run during a test. There can be many load generators for a test. While these Vusers run, they create load on your system, enabling you to analyze your system under load.

A load generator can be located on either a local computer or in the cloud. A performance test can include both local and cloud-based load generators.

Below are the different types of load generators.

Type | Description
--- | ---
Specific | An actual load generator. For example, machine host1, located in London.
Automatch | A load generator placeholder, for example LG1. When you assign an automatch load generator to a Vuser group, you are not assigning a specific load generator to the group, but rather a placeholder for a load generator with specific properties. At runtime, specific load generators in the host pool of the project that have the same properties as the automatch load generators, are allocated in place of the automatch load generators.
Elastic Cloud (Available only if a cloud account has been set up for provisioning load generators and cloud hosts have been provisioned) | A load generator placeholder, for example CLOUD1, that is provisioned on the cloud. When you assign an elastic cloud load generator to a Vuser group, you are assigning a placeholder for a load generator with specific properties according to the load generator image. At runtime, the required number of cloud load generators are provisioned and allocated in place of the elastic load generators. When the run finishes, the cloud load generators are de-provisioned. For more details, see Manage elastic cloud hosts.
Elastic Docker (Available only if the project is linked to an orchestrator in Administration) | A load generator placeholder, for example DOCKER1, that is installed and run on a Docker distribution. When you assign an elastic Dockerized load generator to a Vuser group, you are assigning a placeholder for a load generator with specific properties according to the load generator image. At runtime, the required number of Dockerized load generators are provisioned and allocated in place of the elastic load generators. When the run finishes, the Docker containers and load generators are de-provisioned. For more details, see Provision Docker hosts automatically.

Note: Each Elastic load generator you assign is considered as a group. Therefore, if you define a test with three Elastic load generators under one Vuser group (script), three groups are displayed for each load generator or Docker container when the test runs.

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## Customize load generator attributes

You can customize load generator attributes and then assign them to hosts. When customizing load generator attributes, consider the following:

- Create attributes that represent properties about your hosts that differentiate one host from another host when using them for performance testing.

- Because you can select multiple attributes for your host, you can define an unlimited number of host attributes. They do not need to be related.

- Host attributes can refer to anything. For example, Host Memory - High, Spanish environment, Very slow machine.

To customize host attributes:

1. In Administration, select Maintenance > Hosts, and click Manage Host Attributes.

2. To add an attribute, click Add Host Attribute, and enter a name for the attribute. The host attribute is added to the host attributes list.

3. To delete attributes, select the attributes you want to delete and click the Remove Host Attribute button . The selected host attributes are removed from the host attributes list.

4. To edit an attribute, select the attribute you want to change and click the Edit Attribute button . Modify the attribute as required, and click Close.

To assign attributes to hosts:

1. In Administration, select Maintenance > Hosts, and select the hosts to which you want assign attributes.

2. In the Hosts toolbar, click Assign Host Attributes.

3. Select the attributes to assign to the hosts, and click Assign.

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## Distribute load generators among Vuser groups

This task describes how to distribute load generators among Vuser groups participating in the performance test.

To distribute load generators to groups:

1. Prerequisites.

   Add Vuser groups to participate in the test. For details, see Create groups and distribute Vusers.

2. In the Performance Test Designer window, select the Groups and Workload tab. If load generators have already been assigned to a group, the script name and type, and the number of assigned Vusers and load generators are displayed.

   Action | Description
   --- | ---
   Show load generator names | Click Show LG names to display the names of the load generators. You can also view details of assigned load generators in the Load Generators tab.
   Filter groups | Click the Filter button to filter the list of groups displayed in the grid. For details, see Filter displayed items.
   Replace assigned script | If you want to replace the script assigned to the group with a different script, select the script and click the Replace script for existing group button . Select a script to replace the existing one assigned to the group, and click Replace & Close.

3. From the Groups pane toolbar, click the Assign LGs button . The Assign Groups to Load Generators dialog box opens.

4. In the Groups pane, select the groups to which you want to assign load generators. You can use the Search button to search the list of groups by name.

   - Indicates the total number of Vusers assigned to the Vuser group.

   - Indicates the number of load generators assigned to the Vuser group.

5. Specify the load generators to assign to the groups.

   1. In the Load Generators pane, select the load generators you want to assign to the selected groups from the load generator types listed below (you can assign one or more load generators to multiple Vuser groups at once).

      Use the Search button to search the list of load generators by name. The number of each load generator type already assigned to the Vuser group are displayed adjacent to the load generator type tab.

      Load Generator Type | Description
      --- | ---
      Specific | Enables you to select load generators from the project's host pool to assign to the Vuser groups in the test, or to remove them from the Vuser groups. Name. The name of the load generator. Status. The status of the load generator: Operational, Non-operational, or Unavailable. Assigned load generators must be operational during runtime. State. The current state of the load generator. This includes Idle, Installing, Rebooting, Running. Location. The location of the load generator. Purpose. The purpose of the load generator: Controller, Load Generator, Data Processor, or a combination of these. Note: Only the hosts in the pool with at least a Load Generator purpose are displayed. No. of related groups. The number of Vuser groups to which the load generator is assigned. If a load generator has been assigned to groups, you can click the Expand button to display the related groups list or to unassign groups. Note: While hosts from older installations (up to two versions earlier) are still supported, we recommend upgrading them to the latest version before using them. Earlier versions are no longer supported and cannot be used to run tests.
      Automatch | Enables you to select automatch load generators to assign to Vuser groups in the test, to remove assigned automatch load generators from the Vuser groups, and to add more automatch load generators for the test. Add LGs. Click to add more automatch load generators for the test. Enter the number of load generators in the adjacent box, and click Add. Name. The name of the automatch load generator. By default, these are named LG1, LG2, and LG<n+1> equivalent to the number of automatch load generators that you want to provision. To select all load generators in the list, select the column heading check box. Properties. The properties by which the automatch load generator is matched up with a specific load generator in the host pool of the project at runtime. No. of related groups. The number of Vuser groups to which the load generator is assigned. If a load generator has been assigned to groups, you can click the Display button to display the related groups list or to unassign groups.
      Elastic Cloud (Available only if the project has been linked to a cloud account. For details, see Cloud accounts.) | Enables you to assign or unassign elastic cloud-based load generators to or from Vuser groups, and to add additional cloud load generators to the test. For details, see Provision elastic cloud load generators. Add LGs. Opens the Add Elastic Cloud dialog box, enabling you to add more cloud load generators for the test. Select the load generators and the number of each that you want to add. You can filter the list of load generators displayed in the grid by account, location, size, and/or operating system. Click Add to add the selected load generators and close the dialog box, or Add & Another to add and keep the dialog box open enabling you to add additional cloud load generators. Click the Delete button to unassign the selected cloud load generators. Name. The name of the cloud load generator. By default, these are named CLOUD1, CLOUD2, and CLOUD<n+1> equivalent to the number of cloud load generators that you want to provision. Template Name. Name of the cloud load generator template. OS. Operating system of the cloud load generator. Location. Geographic location (region) of the cloud load generator. Account. Name of the cloud provider (Amazon Web Services or Microsoft Azure). Size. The hardware configuration of the machine from which the load generator is provisioned. This impacts the storage and memory.
      Elastic Docker (Available only if the project has been linked to an orchestrator. For details, see Provision Docker hosts automatically.) | Enables you to assign or unassign elastic Dockerized load generators to or from Vuser groups, and to add additional Dockerized load generators to the test. For more on elastic Dockerized load generators, see Provision Docker hosts automatically. Add LGs. Click to add more Dockerized load generators for the test. Enter the number of load generators in the adjacent box, and click Add. Image Name Selector. Select which load generator image to use for the test. The images assigned to the project are determined by the administrator (in Deploy and manage Docker host images). Memory/CPU Limit Selector. Specify how much of the available memory (in gigabytes) and CPU resources a container can use during a performance test run. Note: If resource limits are set by your administrator (in Set up Dockerized hosts), you cannot enter values that exceed these limits. If you leave these fields empty, the administrator's limits (if set) are used. If the administrator reduces the project limits to a value below after you have configured your settings, your settings are automatically reset to the new limits. Name. The name of the elastic Dockerized load generator. By default, these are named DOCKER1, DOCKER2, and DOCKER<n+1> equivalent to the number of Dockerized load generators that you want to provision. No. of related groups. The number of Vuser groups to which the load generator is assigned. If a load generator has been assigned to groups, click the Display button to display the related groups list or to unassign groups.

   2. Click Apply Assignment to assign the selected load generators to the selected groups in the test.

      Note: This is available only when at least one unassigned load generator and one group have been selected.

6. (Optional) Select properties for automatch load generators.

   You can select properties for the automatch load generators that are assigned to Vuser groups in your test. Properties include a location and other attributes. At runtime, each automatch load generator is matched up with an available specific load generator (in the host pool of the project) with the same properties.

   1. To select properties for automatch load generators, select More > LG Management to open the Load Generator Management dialog box.

   2. Select one or more automatch load generators for which you want to define the same settings, and enter a location and/or host attributes. For details on customizing host attributes, see Customize load generator attributes.

      Example: You want a Vuser group to use a load generator that is located in London and has medium strength and memory. Under Location, select London, and in the Host Attributes list, select Host memory: Medium and Host strength: Medium. At runtime, the system tries to assign a specific load generator with these properties to the Vuser group.

      You can also use the Copy button to copy properties from one automatch load generator, and the Paste button to paste them to multiple automatch load generators.

      To see the updated properties for an automatch load generator, you need to clear the check box, and then select it again.

      For more details, see Manage load generator types.

   Note:

   - You can only copy properties from hosts that are assigned to the test.

   - Properties are only saved for hosts that are assigned to groups within this test.

   - If no properties are specified, the automatch load generator is matched up with any load generator in the project's host pool.

7. To view or modify load generators assigned to a group.

   Action | Description
   --- | ---
   View all assigned LGs | To view all load generators assigned to a group, select the group in the Groups pane, and in the group details pane, select the Load Generators tab. The grid displays the name and load generator type, and the number of groups to which the load generator is assigned.
   Unassign LGs | If you want to unassign load generators from groups or replace them with other load generators, select the groups and load generators that you want to change, and select Unassign or Replace with another LG. Alternatively, you can clear the check box for each load generator you want to unassign, and click Apply Assignment.
   Replace LGs | If you want to replace load generators with other load generators, select the groups and load generators that you want to change, and select Replace with another LG. In the Replace Load Generators dialog box, select the load generators you want to assign to the selected groups.

8. Click Save Test to save your settings.

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## Manage load generator types

You can manage the different load generators types that are available to use in your performance test from the Load Generator Management dialog box.

To configure load generators from the Load Generator Management dialog box:

1. Click the Navigation menu and select Test Management > Tests & Scripts.

2. Select a performance test in the test management tree and click Edit Test.

3. In the Performance Test Designer window, click Groups and Workload.

4. On the Groups pane toolbar, click More > LG Management.

5. Select a load generator type by clicking one of the displayed tabs (Specific, Automatch, Elastic Cloud, Elastic Docker), and then select the load generators you want to configure. Select the Name heading check box to select all the load generators.

6. You can copy properties from a specific load generator by clicking the Copy button and then the Paste button to paste the properties to other selected load generators.

   Note:

   - You can only copy properties from hosts that are assigned to the test.

   - Properties are only saved for hosts that are assigned to groups within this test.

7. You can perform the following actions on load generators from the load generator type tab.

   Action | Available on Load Generator Type
   --- | ---
   Add additional load generators to the test | Automatch, Elastic Cloud, Elastic Docker For details. see Automatch, Elastic Cloud, or Elastic Docker.
   Define/view load generator properties | Define: Automatch only. For details, see (Optional) Select properties for automatch load generators. View: Properties for Specific load generator types are defined by the administrator, and are read-only.
   Enable remote desktop sessions (RDP) | Specific, Automatch, Elastic Cloud For details, see Configure remote desktop session settings.
   Enable terminal services | Specific, Automatch, Elastic Cloud For details, see Configure terminal services settings.

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## Configure remote desktop session settings

You can configure remote desktop session (RDP) settings for Specific, Automatch, or Elastic Cloud load generator types.

To configure remote desktop session settings:

1. Open the Load Generator Management dialog box as described in Manage load generator types.

2. Select one or multiple load generators from the supported load generator types that are available in the test.

3. Configure the following settings.

   Action | Description
   --- | ---
   Enable RDP | Select Enable RDP to support GUI testing, enabling you to run Vusers in an interactive RDP session. For task details, see Run Vusers in an interactive RDP session. Note: Interactive RDP mode is not supported when a host is used simultaneously as a Controller and load generator. RDP mode is not supported for a local system user account. While a performance test with a system account runs for a load generator set to RDP mode, it does not open an interactive RDP session.
   Color depth and resolution | Select Select Color depth and resolution and select the required color depth and resolution to be used to create the RDP session on the hosts running the script. The graphic card of the hosts running the script determines the default color depth and resolution if it does not support the selected one.

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## Configure terminal services settings

You can configure terminal services settings for Specific, Automatch, or Elastic Cloud load generator types.

To configure terminal services settings:

1. Open the Load Generator Management dialog box as described in Manage load generator types.

2. Select one or multiple load generators from the supported load generator types that are available in the test.

3. Configure the following settings.

   Setting | Description
   --- | ---
   Enable Terminal Services | Select to enable terminal services sessions for the selected load generator. For task details, see Configure terminal sessions.
   No. of Terminal Services to open on Load Generator | Enter the number of terminals in your performance test. Note: You must open a terminal session for each terminal on which you want to run Vusers during the performance test.
   Max. number of Vusers to run in a Terminal Service | Enter the maximum number of Vusers that you want to run in a terminal session. Note: The maximum number of Vusers depends on the Vuser type used in the script. For GUI Vusers, the maximum is one Vuser for each terminal session.
   Create new session | Enables the Controller to launch terminal sessions automatically using the Remote Desktop Connection. When choosing this option (the default setting) you must specify the credentials required for automatic login: User Name, Password, and Domain. If you are using a custom user account, make sure that you follow Run terminal sessions with a custom user account. You can also select the Color Depth of the session (High Color (15/16 bit), True Color (24 bit), or Highest Color (32 bit)).
   Connect to existing session | Enables a connection to an existing (open) terminal session. If you select this option, you must open a terminal client session manually for each terminal that you want to run Vusers on during the test run.

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## Assign elastic hosts to a test

Using Elastic Cloud and Elastic Docker hosts automates the testing process by provisioning and de-provisioning hosts on demand, and seamlessly adds them to tests without having to reserve resources in advance.

To assign elastic hosts to a test:

1. Prerequisites

   - To assign Elastic Cloud hosts to a test, a cloud account must have been set up for provisioning load generators. For details, see Provision elastic cloud load generators.

   - To assign Elastic Docker hosts to a test, the project must be linked to an orchestrator (performed by your administrator). For details, see Set up Dockerized hosts.

2. Click the Navigation menu and select Test Management > Tests & Scripts. Select a performance test in the test management tree, and click Edit Test.

3. Assign elastic Cloud or Dockerized load generators to Vuser groups for the test. For details, see Distribute load generators among Vuser groups.

4. (Optional) Set the Post Run Action if your administrator did not set a post run action.

   Note: We recommend selecting Collate Results to ensure that run results are not lost after a performance test ends, because elastic hosts are freed immediately after the run finishes. For details, see Post Run Action.

5. Save and then run the test to check its performance. When the test has finished, elastic hosts are automatically removed from the test. For details on running a test, see Run performance tests.

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See also:

- Define test workloads
- Provision Docker hosts automatically
- Provision elastic cloud load generators

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