June 29, 2022

Performance Testing vs. Load Testing vs. Stress Testing

Performance Testing

If you’re a developer or QA engineer or if you work in DevOps, you know you need to conduct different performance testing types in order to make sure each code change or feature addition (a) doesn’t break the system and (b) works.

But which types of performance tests should you conduct, what’s the difference between load testing and stress testing, and which test is suitable for which situation? In this blog post, we’ll cover the answers to these questions and more.

Table of Contents:

Performance Testing vs. Load Testing vs. Stress Testing

There are multiple types of tests that fall under the performance testing umbrella. For instance, load testing and stress testing are both types of performance testing that check how your application performs when many people use it at once. 

While there are those who compare all three types of testing, the more popular comparisons that testers make include: 

  • Performance testing vs. load testing.
  • Load testing vs. stress testing.

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Let us take a closer look at the above comparisons.

Performance Testing vs. Load Testing

Performance testing generally checks a system’s behavior at any given time, focusing on factors like speed and reliability.

Load testing pays particular attention to how the system behaves when multiple users are trying to engage with it at the same time.   

Load Testing vs. Stress Testing

While load testing simulates real-life application load, stress testing tests application performance at peak times.

Therefore, the main way to differentiate between these two types of testing is by focusing on their end goal.

To summarize, load testing and stress testing are two popular types of performance testing that each focus on different application behaviors, such as a system’s general behavior under load or the upper limits of a system’s load capacity.

With the comparisons out of the way, let us explore each type of testing on its own. 

What is Performance Testing?

Performance testing is the general name for tests that check how the system behaves and performs. Software performance testing examines responsiveness, stability, scalability, reliability, speed, and resource usage of your software and infrastructure.

Different types of performance tests provide you with different data, as we will further detail.

Before performance testing, it is important to determine your system’s business goals, so you can tell if your system behaves satisfactorily or not according to your customers’ needs.

After running performance tests, you can analyze different KPIs, such as the number of virtual users, hits per second, errors per second, response time, latency, and bytes per second (throughput), as well as the correlations between them. Through different test reports, you can identify bottlenecks, bugs, and errors, then decide what needs to be done.

When to Use Performance Testing

Run performance tests when you want to check your website and app performance, which may extend to testing servers, databases, networks, etc. If you follow the waterfall methodology, test at least once before you release a new version of your application. If you’re shifting left and going agile, you should test continuously.

The following figure shows an example of a performance testing report on BlazeMeter. This is a good test, given the growing number of users does not affect the response time, the error rate remains low, and the hits per second rise with the number of users, but remain stable.

performance testing report on BlazeMeter

What is Load Testing?

A load test is a type of performance test that checks how systems function under a heavy number of concurrent virtual users performing transactions over a certain period of time

In other words, the test measures how systems handle heavy load volumes. There are a few types of open-source load testing tools, JMeter being the most popular.

When to Use Load Testing

Load test when you want to determine how many users your system can actually handle. You can configure tests to simulate various user scenarios which can focus on different parts of your system (such as a checkout page, for example).

You can determine how the load behaves when coming from different geo-locations or how the load might build up, then level out to a sustained level.

Load tests should be performed all the time in order to ensure your system is always on point, which is why it should be integrated into your continuous integration cycles (utilizing tools such as Jenkins andTaurus.)

The following figure shows what a load test can look like in JMeter. This test analyzes adding 100 users every 30 seconds until reaching 1,000 users. The entire stepping process takes 300 seconds. After reaching 1,000 threads, all of them will continue running and hitting the server together for 5 minutes.

JMeter load test

What is Stress Testing?

A stress test is a type of performance test that checks the upper limits of your system by testing it under extreme loads, a simple task with a tool like BlazeMeter. Stress tests examine how the system behaves under intense loads and how it recovers when going back to normal usage. Are the KPIs like throughput and response time the same as before spike in load? Stress tests also look for memory leaks, slowdowns, security issues, and data corruption.

Stress testing can be conducted through load testing tools by defining a test case with a very high number of concurrent virtual users. 

Just as a stress test is a type of performance test, there are types of load tests as well. If your stress test includes a sudden, high ramp-up in the number of virtual users, it is called a Spike Test. If you stress test for a long period of time to check the system’s sustainability over time with a slow ramp-up, it’s called a Soak Test.

The following example shows how to create a traffic spike using JMeter’s “Ultimate Thread Group” component. We presume the system will be under traffic three minutes into the test. We define more threads to be added within fixed time windows using the “Initial Delay” setting.

Sample stress test

When to Use Stress Testing

Run stress tests against your website or app before major events, likeBlack Friday, ticket selling for a popular concert with high demand, or elections. We recommend stress testing every once in a while so you know your system’s endurance capabilities. This ensures you’re always prepared for unexpected traffic spikes and gives you more time and resources to fix your bottlenecks.

Other Performance Testing Types

While load testing and stress testing are two of the most popular types of performance testing, they are far from the only performance testing options available. 

Let us explore three other types of performance tests: soak tests, spike tests, and scalability tests.

Soak Tests

Also known as endurance testing, capacity testing, or longevity testing, soak testing tracks how an application performs under a growing number of users or draining tasks happening over an extended period. 

Soak tests are especially known for their extended duration. Once you go through a ramp-up process and reach the target load that you want to test, soak tests maintain this load for a longer timeframe, ranging from a few hours to a few days.

Spike Tests

Spike testing assesses performance by increasing the number of requests very quickly up to stress levels and decreasing it again soon after. A spike test will then continue to run with additional ramp-up and ramp-down sequences in either random or constant intervals to ensure continued performance.

Spike tests are great to use for scenarios like auto-scaling, failure recovery, and peak events like Black Friday.

Scalability Tests

Scalability tests measure how an application can scale certain performance test attributes up or down. When running a scalability test based on a factor like the number of user requests, testers can determine the performance of an application when the user requests scale up or down.

Bottom Line

Utilize all the types of performance tests detailed here to ensure you are always aware of any issues and can have a plan for dealing with them.

With BlazeMeter, teams can run their performance testing at a massive scale against all your apps, including web and mobile apps, microservices, and APIs. With advanced analytics, teams using BlazeMeter can validate their app performance at every software delivery stage.

BlazeMeter lets you simulate over two million virtual users from 56 locations across the globe (Asia Pacific, Europe, North and South America) to execute performance tests continuously from development to production. 

See for yourself how you can easily build, scale, analyze, and automate performance tests.



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