Distribute load generators

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

Load generator types

A load generator is a host machine on which Vusers run during a test. There can be many load generators for a given test.

There are three types of load generators:

Type

Description

Specific load generator An actual load generator. For example, machine host1, located in London.
Automatch load generator 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 load generator

(Available only if the project is linked to an orchestrator in Performance Center Administration)

A load generator placeholder, for example DOCKER1, that is installed and run on a Docker distribution. When you assign an elastic 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 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.

Back to top

Estimate how many load generators you need

To estimate the number of load generators that are needed to run a Vuser script, you can use the Load Generator Calculator tool (Technical Preview). On the host machine, select Start > Programs > Micro Focus Software > Performance Center Host > Tools > Load Generator Calculator.

Back to top

Customize load generator attributes

You can customize load generator attributes. For details about how to customize host attributes, see Customizing Project Entities in the ALM Lab Management Guide.

When customizing load generator attributes, consider the following:

  • Create attributes that represent properties about your hosts that will help tell one host apart 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.

Back to top

Distribute load generators among Vuser groups in a test

  1. Prerequisites

    Add Vuser groups to participate in the test. For details, see Define a performance test workload.

  2. In the Performance Test Designer window, click Groups & Workload. On the Groups pane toolbar, click Assign LG. The Assign Load Generators dialog box opens. For user interface details, see Assign Load Generators to Groups dialog box.

  3. Select the groups to use in the test

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

    If load generators have already been assigned to a group, you can see the list by clicking the button. You can unassign load generators using the x or Unassign All button.

  4. Specify the load generators to assign to the groups

    1. In the Load Generators column, select the load generators you want to assign to the selected groups from the following load generator types: Specific, Automatch, and/or Elastic. For an explanation about the different load generator types, see Load generator types.

      You can use to search the list of load generators by name or attributes.

      Note:  

      • The Elastic tab is displayed only if the project has been linked to an orchestrator. For details, see Manage elastic load generators.

      • For automatch or elastic load generators: You can add additional load generators to the list by clicking , and entering the number of additional load generators required for the test. You can also, update load generator properties by clicking the Properties link. For details, see Load Generator Management dialog box.

    2. Select the check box for each load generator you want to assign to the selected groups.

      To select multiple load generators, click and drag a box around the load generators you want to select. To select all load generators in the column, select the check box next to the Name column heading, or press CTRL + A.

    3. Click to open the Preview window, where you can review all the load generator assignments.

    4. Click Assign to assign the selected load generators to the selected groups in the test, and then click OK to save your changes.

      Conversely, if you unassigned load generators from groups, click Unassign, and then click OK to save your changes.

  5. Select properties for the automatch load generators - optional

    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, expand the Automatch tab, and click the LG<#> link 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.

      You can also use to copy properties from one automatch load generator, and 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 user interface details, see Load Generator Management dialog box.

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

Back to top

Assign elastic load generators to a test

Using elastic load generators automates the testing process by provisioning and de-provisioning load generators on demand, and seamlessly adding them to tests on the fly without having to reserve resources in advance.

  1. Prerequisites

    To be able to assign Dockerized load generators to a test, the project must be linked to an orchestrator (performed by your Performance Center administrator). For details, see Set up elastic load generator provisioning on Windows or Linux containers.

  2. Select a test

    From the Performance Center navigation toolbar, click and select Test Management (under Testing). Select a performance test in the test management tree, and click Edit Test.

  3. Assign elastic load generators to Vuser groups

    Follow the steps in Distribute load generators among Vuser groups in a test, and assign elastic load generators to the groups for the test.

  4. Set Post-Run Action to collate results (if your Performance Center administrator did not set a post-run action)

    To ensure that run results are not lost after a performance test ends (since elastic load generators are freed immediately after the run finishes), we recommend you select Collate results. For details, see Run Test dialog box.

  5. Run the performance test

    Save and then run the test to check its performance. For details on running a test, see Manage a performance test run.

    When the test has finished, the elastic load generators are automatically removed from the test.

Back to top