Cloud Load Engine - Web Performance
Cloud Load Engine

Cloud Load Engine

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New with Load Tester's 4.0 release is the ability to create and utilize load engines running in Amazon's EC2 Cloud. This feature complements Load Tester's built-in load engine, and is a simple and easily available way to generate more testing load than you could from a single computer.


Using cloud load engines is a comparatively inexpensive alternative to acquiring, configuring and running additional dedicated hardware. Only a few steps are needed to configure a cloud client and to run tests.

Configuring a Cloud Client

You will use an EC2 account that you have already established with Amazon Web Services. See the AWS EC2 tutorial for help setting up an account.

In Load Tester, go to Window->Preferences and select the Web Performance->Cloud Accounts node as shown below. Then press the Add... button. Read the short disclaimer, and agree to it.

Window->Preferences menu selection

Cloud Accounts window

At this point the dialog will ask you for your Access Key ID and Secret Access Key.

Credentials for Cloud Account

To get these keys, log into your Amazon account and choose Your Account->Security Credentials to see a screen resembling this example:

AWS Access Key and Secret Key

Copy and paste your Access Key ID into field (1) shown in the previous image above.

Generate a Secret Access Key if you do not already have one, show it, and paste it into field (2).

Select the geographical region, field (3), in which your load engine is to run.

Optionally, select the appropriate security key, field (4). Press the help icon for more information.

You will note that there is a check box labeled Create Security Group if Needed. By default, it is checked, which will be correct for most use cases. If you do not already have an Amazon security group created by Load Tester, an appropriate group will be created for you. When the load engines start they'll need to open proper ports in their internal firewalls. Without the correct security group settings you would not be able to connect to the engines after you created them.

The Load Tester now has the security credentials that are required for it to access and control your EC2 account as it allocates and connects to engines running in the cloud.

The OK button is disabled until you have provided valid credentials. If the OK button is not enables, but there is no error message, pressing the Verify button will force verification. 

Subscribe to Load Tester

After you press OK for the credentials, you will be prompted to subscribe to the Load Tester in your Amazon account:

"Almost Done" screen

For any new Amazon account you must subscribe to Load Tester on the Amazon subscription screen. Subscription is needed only once per account, and does not incur a setup fee or a monthly fee. Your charges are based on bandwidth and actual usage. See the usage section of the Amazon screen for an explanation of the charges.

Here is an example showing confirmation of an Amazon subscription for Load Tester:

Amazon subscription screen

Prepare for Load Test

You have probably already created load tests and are familiar with the process of running tests with Load Tester. If you are not, see our tutorials and videos to help you get started. When you have a load test ready to run, you can continue with this tutorial.

Adding Engines

Bring up the Engines View and press the Add Engines button. Select Create new cloud engine(s) using your Amazon EC2 account and press the OK button. 

Adding Engines

Specify the number of engines you intend to start. The Instance image will automatically be selected for you. The security group field should automatically select the security group created in an earlier step (WPLoadEngine). Selecting a security group with the wrong permission may prevent use of the load engine.

Pressing the Create button in the Create Cloud Engines dialog creates the instances in the Amazon cloud, and can eventually be seen in the Instances section of the AWS Management Console.

Screen for creating cloud engines

As the engine starts up, Load Tester's Engines tab shows the engine's status. It will initially show pending, then running, and eventually Idle, when the engine is ready for use.

Engine Idle

Running the Tests

You can click the check mark in the Engines view to alternate between running and Idle. With the engine idle, press the start  button image button in the Load Configuration view, and watch the test run.

As the test runs, the Load Configuration view continuously displays updated charts, including the CPU and memory utilization of the load engines. See the tutorials and videos for examples of the charts and for information about interpreting them, as well as for instructions on generating reports that summarize the test results.

After you have finished the tests

When you no longer need the load engines, you may select the Engines view, select the engines to be removed, and click Remove to remove each load engine, terminating the load engine's instance. Your load engine will now be shut down in EC2.

Shutting down the cloud engine

To avoid any unnecessary charges to your EC2 account, Load Tester automatically asks you whether it should shut down unterminated engines if any remain at the end of a load test run, or when you shut down Load Tester.

We recommend that you always log into the AWS Management Console for your account and inspect the dashboard to verify that all your load engine instances have terminated. To terminate an instance inadvertently left running, select it and click Instance Actions > Terminate, as shown in this example:

Terminating an EC2 Engine

Feedback & Comments

Comments about this report may be posted at the company blog post.


Peter A. Neilson
�2009 Web Performance, Inc.; v1.0

Version History

v1.0 - 1st public release (24 September 2009)


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