Load testing and stress testing are often seen as analogs because they’re types of performance testing. Both primarily intend to make us aware of the possibilities and criteria of the software’s operation in states of vast exploitation by a given group of users and prevent unforeseen, unauthorized actions, such as DDOS attacks carried out by hackers.
However, there exists a fine line of difference between load testing and stress testing that lies in their meaning, process, goals, and other similar factors. If you’re considering performance testing services, it is necessary to understand these differences; why are load and stress tests are carried out, and what are their main goals? What basic tools are used for testing, and are there any benefits of load and stress tests? We will present these main divisions of performance tests and indicate other interesting real-life cases where they are carried out.
Load Testing Meaning
Load testing is a non-functional testing that measures a module or system’s behavior given increasing load, such as the number of active users at a time or the transaction number, to determine the upper load limit the module or system can handle. It also helps in finding application bottlenecks.
Why Do a Load Test?
The main goal of a load test is to describe the optimal load a system can manage without significant performance deterioration. Load tests ought to simulate users, which would enable testing the software’s capacity at the expected load.
Hence, this testing is suitable for complete applications with all their major features. In such a way, load testing will be more сomplex and effective. Load tests are also practical when separate software components (for instance, when the system is divided into microservices, and you need to test their interaction speed).
Load Test Example
For example, we can imagine that company X built an app for an estimated 10,000 users. The objective was to run an advertising campaign for a new product that is very much in demand. So, company X invests a large part of its funds in the product’s advertising campaign. The product can be pre-ordered at a great discount, but only through the app.
On the day of the premiere, sending the purchase form is repeated at the same time by a considerable number of people, and everything goes fine. But subsequently, requests (information sent by users) sent to the server begin to accumulate because the resources associated with the server only allow for the execution and processing of a finite number of inquiries and responses.
With the advancement of time and the increase in the number of users willing to purchase the X product, the situation gets out of hand, resulting in a complete application failure. Although company X spent enormous amounts of money on advertising campaigns and attracted many potential customers, it failed to achieve its goal through negligence. Its image also suffers.
Doing load testing here helps us achieve two things. First, it ensures that the app can indeed carry the estimated 10 000 active users. Second, it avoids the situation presented above.
Benefits of Load Tests
What does load testing help us do? Here are some of its advantages:
- Minimizes the cost of failure for organizations.
- Improves software scalability.
- Guarantees greater customer satisfaction.
- Reduces the risk for system downtime.
- Helps identify inefficient codes. Identifies hidden bugs in the system.
- Facilitates simultaneous web app usage by multiple users.
Stress Testing Meaning
In this type of testing, the most critical aspect is the assimilation of many users operating simultaneously, exceeding the server resources’ capabilities, and then testing whether the software reacted appropriately and predictably. Application defects that cause data loss or memory leaks are also examined and found.
Why Do a Stress Test?
A stress test’s main goal is to estimate the software’s strength and error handling abilities under hefty load circumstances and guarantee that the app doesn’t crash under overbearing conditions.
Stress Test Example
As already mentioned, in life, we can come across many applications that connect, for example, to servers via the internet, which are used by a certain number of recipients logging in, be it in offices, in companies and enterprises, or on ordinary websites. It happens that such an application or website works very well in a limited environment for a small number of recipients. However, under the influence of increased activity, various unpleasant things start to happen.
As an example, a gaming company decides to release an online game. In the first hours after the production’s final release, the servers were unable to withstand the players’ activity. Many incoming data resulted in overloading and complete shutdown of the servers, and players lost server connection for several hours until the failure was resolved. As you would expect, the players felt disappointed that they could not play the game, even after purchasing the premier package.
In contrast to a load test, an early stress test in the above example would have helped ascertain the maximum number of active users the game app could carry before the servers broke down. And of course, validate if the software can tolerate errors while handling this maximum load.
Benefits of Stress Testing
Here are a few advantages of a stress test:
- Finds bugs and some synchronization problems
- Detects Interlock flaws (mutually dependent functions)
- Requests priority issues
- Reveals loss of resource problems
- Catches memory leaks
- Identifies system’s corruption and loss
What are the Differences and Similarities between Load Testing and Stress Testing?
The differences between load and stress testing are elaborated in the table below:
| Load Testing | Stress Testing |
| We assess if the software functions as intended under a given load. | We assess if the software functions as intended under maximum pressure. |
| We determine the app’s operational capacity. | We determine the app’s error tolerance and security outages. |
| Load stays within the expected threshold | Load/pressure is beyond the expected threshold. |
| Testers’ logic is to establish an acceptable efficiency of the system. | Testers’ logic is to establish the max efficiency of a system. |
| This can be carried out as soon as the load bearing receiver, capacity, or storage is developed and integrated into the software | This can be carried out as soon as any operational script is written. |
| Checks require simulating the external data/ loads effects coming into the software | Checks require simulating both internal and external operations’ effects coming in or out of the software. |
Still, load testing and stress testing have some things in common. Their similarities include:
- They are performance test types as their purpose is to guarantee that an app works effectively as intended.
- Both testing should be integral parts of the SDLC (and not merely after everything ships and the app goes to production).
- These two tests equally require execution by skilled QA engineers with the right frameworks, tools, and test environments.
Stress Testing and Load Testing Tools
Frequently used load and stress testing tools include:
Apache JMeter: is among the most common and popular tools dedicated to performing performance, stress, and functional tests. This program is written in Java and free-to-use. It allows users to download additional plugins. Its GUI is easy-to-operate (but when performing load tests, it is advisable to execute using commands from the CMD console). This lets the user run tests from multiple machines at once. Also, you can collect and analyze statistics in detail, and generate reports. However, the tool’s shortcoming is that it has extensive hardware requirements for the app to operate (mainly memory resources). The GUI with Java is reflected in the application speed, which may disturb the measurements. JMeter can be used primarily to send GET requests.
Gatling: This is a free Apache-based benchmarking tool written based on the Scala language. It has an asynchronous architecture. It introduces the messaging-oriented actor model instead of creating dedicated threads (this generates more significant overhead). It fully supports JMS and HTTP protocols.
SoapUI: This is a tool primarily designed to automate web service tests based on the SOAP protocol. (Simple Object Access Protocol – is a network protocol that uses XML to code calls). It supports functional, stress, and security tests. It allows you to test REST, JMS, AMF, and JDBC applications.
Conclusion
In summary, performance tests, such as load testing and stress testing, are an essential element in the testing culture. They should be carried out relatively systematically with the development of the application. Thanks to them, we can obtain the data we need to estimate appropriate and optimal resources for the application’s proper operation. These tests also help us find errors caused by a large amount of data and create protection against external attacks.
That said, obtaining the correct data from performance testing is no easy job. Performance test metrics are integral to any software’s success. It’s crucial that QA teams monitor the chief performance metrics during testing and focus on these areas to assess an application’s health accurately. After all, key success factors are only applicable if they are acknowledged and tracked.
To understand which KPI matters during performance testing, check out our blog post on software performance metrics.
