Application software is developed to be uploaded and run on the internet. Thus its performance is crucial for its success. Statistically, if a web application takes more than 5 seconds to load, the chances of the user bouncing off the website increase by 90%. Similarly, if there are too many elements present on a page, the user conversion rate drops by about 95%. Both instances harm the bottom line of the software customer.
Hence, any software or app needs to undergo load and stress testing. Both the tests form a part of the non-functional testing but the objectives and methods used are subtly different from each other.
While the load test measures the system performance when faced with unexpected load, a stress test measures the breaking point of a system by overloading it way beyond the normal operational limits. In load testing, the load limit applied is the same as the breaking point threshold while in stress testing, the load limit exceeds this breaking point.
Load testing is performed using multiple users, while stress testing is conducted under varying data volumes.
Thus load test can be said to test the performance of the system or application and determine its operating capacity while stress test checks for stability, robustness and security of the system or application that is under test.
Load and stress test objectives
Load testing helps the user to understand if the hardware and infrastructure present is capable of handling the load that is expected to be put on it. Key indicators that are monitored here are CPU and the current memory utilization, network throughput, I/O reads and others. The results of the load test enable the hardware architects and infrastructure teams to:
- Re-establish metrics for baseline performance and
- Redo capacity planning to meet the requirements.
The stress test, on the other hand, helps identify issues occurring due to the overloading of the current system. It also checks to see whether the system can recover from this overloading.
Thus both of these tests are critical for customer-facing apps since they help to identify and remove plausible bottlenecks before the software goes into production. It is a proactive approach which needs to be taken early.
Since the tests include load and stress simulation, manually performing it is a cumbersome, time-taking and inefficient process. With test automation services, both the required load and stress can be stimulated and emulated, thereby ensuring the accuracy of results so that precise methods can be adopted to clear the bottlenecks. Thus automation of these tests helps to:
- Avoid bad customer experiences, launch failures,
- Provide developers with quick feedback about performance errors and,
- Enable performance regression checks, especially in the CI/CD pipelines.
Simply speaking, these test automation services help to simulate users realistically so that the performance, scalability and reliability of the app infrastructure can be checked. Thus these tests help identify:
- Software designing issues like incorrect concurrency, memory build-up, poor optimization etc.,
- Server configuration issues related to the web, database and application server, load balancer and others,
- Hardware limitations like CPU maximization, network bottleneck, memory limitation etc.
Using automation services for load testing
The following steps need to be undertaken to enable automation of load testing:
- Creation of a dedicated load testing environment,
- Defining the load testing scenarios,
- Determining the load testing parameters and transactions for the app with stress on:
- Data preparation for each transaction,
- Prediction of the possible number of users who will be accessing the system,
- Determining connection speed after taking into account even those users who might connect trough dial-up modems and leased lines,
- Taking stock of the different operating systems and browsers that the users are likely to use,
- Configuring all the available servers like application servers, DB servers and web servers.
- Execution of the load test scenarios with constant monitoring and collection of the required metrics,
- Analysis of the obtained results and making the required recommendations based on the same,
- Fine-tuning and configuring the system according to the recommendations made and
- Re-testing the system.
The whole cycle needs to be run as many times as the system is fine-tuned and configured to achieve an error-free environment with regards to load testing.
There are certain guidelines which need to be followed for automated load testing like:
- The application needs to be functionally stable,
- Data pool needs to contain a vast amount of unique data,
- Each scenario or script needs to have a predefined number of users,
- Detailed log creation needs to be avoided since they take up disk I/O space,
- Website image downloading should be avoided,
- Response time consistency over the elapsed period needs to be logged and compared.
Using test automation services for stress testing
There are 5 steps involved in performing an automated stress test. They are:
- Planning stage wherein data is gathered to analyze the system and define the goals of the stress test,
- Creation of automation scripts so that stress scenario data can be generated,
- Execution of the created scripts involves stress testing these automated scripts and storing the results,
- Analysis of the stored results enables software developers to identify possible bottlenecks and
- Tweaking and optimization stage wherein the system is fine-tuned, configurations changed based on the stress test results and the code is optimized with the goals to meet the required benchmark set.
This entire cycle needs to be run as many times as changes are made to the system. This finally results in an error-free system and entirely in sync with the performance goals.
Some commonly used metrics for evaluating stress test are:
- Measurement of scalability and performance with regards to pages per second, throughput, rounds etc.
- Application response regarding hit time, page time, time taken to return the first byte etc. and
- Failures as in failed connections, rounds and hits.
There are several test automation service tools available to enable both load and stress testing as well as test the performance of the software developed. These tools need to be implemented to ensure accurate and precise implementation of the load and stress tests and enable software developers to clear all hassles proactively.