When running a load test, ReadyAPI sends requests to the service, and then analyses responses from it. This is a demanding task, especially when simulating a large number of virtual users. Large-scale load tests that simulate 500 and more virtual users need more powerful hardware than the average ReadyAPI installation.
If your load test hits a hardware bottleneck, the load simulation will become unstable, and the test results will no longer be reliable. Depending on the resources on your computer that ReadyAPI can access, it may fail to simulate the number of users required for the test, or prevent the system from responding until the end of the test.
In this topic, you can find some recommendations for your load tests.
Up to 500 virtual users
To run a load test with 500 or fewer virtual users, we recommend the following system configuration:
- A 64-bit operating system.
- The 3rd generation (or newer) Intel Core i7 desktop processor (or an equivalent AMD processor).
- 16 GB of RAM.
- An SSD disk with enough space to store data.
- A network connection sufficient to handle all transactions. (The actual bandwidth required depends on your test)
We do not recommend simulating more than 500 virtual users on a single machine regardless of the hardware. Instead, distribute your tests to multiple computers in your network, or use Amazon images to run your tests from the cloud.
The hardware recommendations above assume that you are using a simple project. If your test is large, uses many assertions, test steps and data sources, you may need a more powerful CPU and more RAM.
Up to 5000 virtual users
We do not recommend simulating over 500 virtual users from one computer. Instead, use one of the following options:
Over 5000 Virtual Users
To run a load test with over 5000 virtual users, distribute it to multiple r3.2xlarge Amazon EC2 instances, with each instance simulating 5000 or fewer virtual users.
Factors affecting performance
It is impossible to tell exactly what hardware you will need to run your test more efficiently. Here are some factors that may impact your test performance:
The number of virtual users
As you add more and more users, it becomes increasingly complex for the computer to handle all parallel events, leading to system slowdown and errors.
Complexity of your SoapUI and LoadUI tests
Send a short request and get a simple response requires minimum resources. Sending a large file in a request, parsing the response and using extracted data to configure the subsequent request is a lot more demanding.
Using files from the hard drive
Read and write operations with files stored on the hard drive require a long time, especially if these files are on HDD (non-SSD) drives. We recommend limiting these operations as much as possible.
Select the VU number
For more information on the factors that affect the load test performance, and on how to find the number of VUs your computer can run, see Set Virtual User Number.