Load generators are the machines that run the Vuser scripts in your scenarios. Each Vuser script that runs on a load generator results in a single Vuser. Each load generator can run multiple Vuser scripts, thereby resulting in multiple Vusers. While these Vusers run, they create load on your system, enabling you to analyze your system under load.
Creating a load generator
To create a load generator, you install LoadRunner's Load Generator software on a host computer. Load generators can be either Windows-based or Linux-based. For details on how to install the appropriate Load Generator software, see the LoadRunner Installation Guide.
Calculating the number of load generators
To estimate the number of load generators that are needed to run a Vuser script, use the Tools > Load Generator Calculator.
Including load generators in a scenario
After you have installed the Load Generator software on a host computer to create a load generator, you can include the new load generator in a scenario. You use the Controller to add the new load generator to a scenario.
In order to enable a scenario to develop significant load on a system, a typical scenario may include multiple load generators. You define and maintain the list of load generators that are available in a scenario. When you add a load generator to the list of load generators in a scenario, you define various attributes of the load generator, such as the platform on which the load generator runs. You can modify some - but not all - of these attributes after the load generator is created.
Note: If a script was created in a version of VuGen or TruClient that is later than the controller version, the script may not run. In this case you may be prompted whether to allow the script to run. A notice will be put in the Load Generator log.
Status of a load generator
The Controller's Load Generators dialog box shows the status of each load generator in a scenario. The status of a load generator changes during a scenario run. For example, when you add a load generator to the list of load generators in a scenario, the load generator has the status Down. The status of the load generator changes to Ready when the load generator is connected to the Controller and is available to run Vuser scripts, and then to Running while the load generator executes a Vuser script. For a full list of load generator statuses, see Load Generator Status Values.
Load generator configuration
In order to create and run accurate real-life scenarios, you can configure numerous settings for each load generator that is included in a scenario. For details on how to modify these settings, see How to Modify Load Generator Settings.
Local vs. cloud-based load generators
A load generator can be located on either a local computer or in the cloud. A scenario can include both local and cloud-based load generators. The procedure for defining and maintaining load generators is similar for local and cloud-based load generators. For details on cloud-based load generators, see Adding a Cloud-Based Load Generator - Overview.
Enabling and disabling a load generator
If a specific load generator is included in the list of load generators for a scenario, but is temporarily unavailable for a particular scenario run, you can disable the load generator instead of removing it permanently from the list. You can then enable the load generator if and when it becomes available.
Note: The LoadRunner standalone Load Generator (LG SA) and standalone Monitor over Firewall (MOFW SA) cannot be installed on the same machine. However, LG SA can be used for monitoring purposes, the same way as the MOFW SA. Note that a single machine cannot be used simultaneously for both running Vusers and monitoring.