Performance Testing, Load Testing & Stress Testing Explained
Performance testing is key for understanding how your system works. Without good performance testing, you don’t know how your system will deal with expected—or unexpected—demands.
Load testing and stress testing are two kinds of performance testing. Knowing when to use load testing and when to use stressing testing depends on what you need:
Do you need to understand how your system performs when everything is working normally?
Do you want to find out what will happen under unexpected pressure like traffic spikes?
To ensure that your systems remain accessible under peak demand, run your system through performance testing.
Let’s take a look.
Performance vs load vs stress testing
Performance testing is an umbrella term for load testing and stress testing.
When developing an application, software, or website, you likely set a benchmark (standard) for performance. This covers what happens under:
Regular parameters: If everything goes as planned, how does it work?
Irregular parameters: Can my website application survive a DDoS attack?
Load testing is testing how an application, software, or website performs when in use under an expected load. We intentionally increase the load, searching for a threshold for good performance. This tests how a system functions when it faces normal traffic.
Stress testing is testing how an application, software, or website performs when under extreme pressure—an unexpected load. We increase the load to its upper limit to find out how it recovers from possible failure. This tests how a system functions when it faces abnormal traffic.
Now let’s look at each in more detail.
What is performance testing?
When you want to find out how the components of a system are performing under a given situation, performance testing is the way to go. You’ll want to find out three key factors about your product:
The resource usage
As a subset of performance engineering, this type of testing addresses performance issues in the architecture and design of the system. Using performance testing tools, we can begin practicing risk management.
Load testing and stress testing are merely subsets of performance testing. As such, performance testing is a wide term that encompasses:
How frequently you test performance depends on your development methodology:
A team using a waterfall approach will want to test with each individual release.
If they are using the agile methodology, performance testing should be a constant practice alongside development.
Why use performance testing?
Want to establish the benchmark behavior of your system? The first step to testing your functionality is performance testing. During performance testing, you’re looking to meet or exceed a number of industry-defined benchmarks.
Importantly, performance testing is not in any way aimed at finding defects with the application.
Rather, it’s meant to set the benchmark and standard for the application. The key is to ensure that utmost accuracy is observed during performance testing. Close monitoring is necessary for ensuring the performance of a system or application.
When setting a benchmark, examine attributes such as:
These are examples of KPIs—Key Performance Indicators. Essentially, performance testing analyzes KPIs like these.
Performance testing best practices
When or how often to performance test depends on what kind of testing you are doing. Here are some tips for getting the most out of your performance testing measures.
Your performance testing should not include any actual users. Performance testing should use software to measure how well it performs or does not perform. User Acceptance Testing (UAT) is when we start to use real software or system users to see how it performs in the real world.
Test as often as possible. There are specific times to test, usually near the last step. When it is time to test, do it repeatedly. Repeat tests over and over to get the most accurate results. If your application, software, or website can successfully pass the tests over and over again, you can tick it off as ready for the next stage.
Do not change what you are testing. When we make lots of changes to an experiment, it becomes more difficult to identify what exactly we’re testing. Between each test, your environment should stay the same. This includes the load or stress that you place upon the system.
Use automated tools to make the process as simple as possible. Automating your testing process will boost efficiency. You can:
Save time and money
Minimize navigating complex architecture
Provide more accurate results faster
Common tools for performance testing include:
Visual Studio Test Professional
Micro Focus LoadRunner
What is load testing?
Load testing is the process of putting pressure on a software, system, or device to measure its response under an expected load.
By simulating production (pressure), load testing shows the behavior under normal and expected peak conditions. The goal is to ensure a given function, system, or program can handle what it’s designed for. This is important because when you’re building your product, you’re only accounting for a few individual users. Load testing helps you prepare for what happens when you deploy your product to hundreds or thousands of users.
More specifically, the goals of load testing include:
Determining the upper limit of all the components of an application (the hardware, database, network, etc. ). This test ensures that the application has the ability to manage any load it will be exposed to in the future.
Detecting defects in applications that relate to buffer overflow, memory mismanagement, and memory leaks. Load testing is likely to expose a number of issues including bandwidth issues, load balancing problems, and the carrying capacity of the system.
Usually, you load test a system that is as close as possible to becoming a finished product, ready for deployment to the masses. It shows your team whether the product is working as expected and/or intended, under the given conditions.
How load testing works
During load testing, the system is taken through a steadily and constantly increasing load until it reaches the threshold. You want to find the weight limit—the weight (load) of activity that an application, software, or website can handle under normal conditions.
The weight limit should be our peak load. Load testing should help you identify:
Page load issues
Additional issues arising when multiple users accessing the system
Good load testing probably looks something like this:
We have four bars to look at:
Green means hits (visitors)
Red means errors
Yellow means response time
Blue means users
This is a good experiment for a number of reasons. We want to see the blue and green lines climbing while the yellow one stays relatively flat. If the yellow line drops, we know that the software can’t stand up to high demands (users and visitors).
As we add hits to the software, the system should be able to withstand traffic until we reach our expected weight limit. Seeing a drop in the yellow line on the graph would indicate that there is a problem and that the weight limit is a lot lower than desired. If it can’t perform well with the expected load, there may be some serious problems in the design.
Of course, you want to know what will happen to the system when the traffic increases suddenly. You may not be able to detect some of these issues during development and testing. This could include testing for:
Traffic from different or varying geo-locations
Sudden spikes in traffic
When to load test
Load testing as a process doesn’t start till a project is close to its end. This is when system performance and actual user engagement can undergo accurate simulation and testing.
(Technically, you don’t have to wait till software development is completed before testing. You can test a specific component in a focused way for the load at any stage of the development process. Still, to test the demand of hundreds of thousands of users, it’s best to wait till development is nearly complete. )
Load testing tools usually mimic the actions of multiple concurrent users of the program, website, app, etc. It is a repeated procedure that involves collecting and monitoring both software and hardware statistics. Of particular interest are the:
Memory of the physical servers
The test will also show the response time and throughput of the system along with other KPIs. When checking backend performance issues, the endurance of input over prolonged periods of time or simultaneous user input is important to understand. However, checking for things that could cause lag, broken functionality, or memory leaks before completing development is load testing in a limited form.
After analysis, the load testing software will generate a load testing report. Compare these results to your expected goals (benchmarks).
What is stress testing?
Where load testing tests expected loads, stress testing applies unrealistic load scenarios—to the point of overloading the system till it breaks. The aim is to find out how stable your product is by stretching it beyond its bandwidth capability. Stress testing evaluates how an application will behave beyond normal conditions and normal peak load.
Why do you need to know this ahead of time? The biggest reason is to see whether your sensitive data remains protected when the system fails. Is there a particular situation where you’re more vulnerable to data leaks?
When you stress test, you deliberately induce failures to analyze the risks at the breaking points. You can then tweak the programs to make inevitable failures more graceful. If it’s going to break, we want our functionality testing to show that it can recover! Exploring the outer limits of a system is the best way to do this.
Some of the issues that can be exposed during stress testing include:
When you’ve completed a round of stress testing, analyze the post-crash report to understand whether your application failed gracefully, as expected—or not.
How to stress test
Stress testing works on anything you’re developing: software, an app, a website, or a backend system, like a host server. The key to successful stress testing is ensuring a controlled environment before and during the test.
Stress testing can include various activities such as:
Overloading the system with lots of jobs
Removing system components
Checking the behavior when the number of users suddenly increases (known as spike tests)
Checking the sustainability of a system over a period of time through a gradual increase in the number of users (known as soak tests)
Performance testing is critical
Performance testing of any kind is not merely a development need—it’s a business requirement.
Stakeholders and customers demand fast and reliable digital experiences. This means that your applications must be able to support thousands or even hundreds of thousands of users seamlessly. Knowing what test to do at what time and for what purpose will help you achieve this goal.
Still confused? This is a helpful video about JMeter, an open source performance testing tool:
BMC IT Operations Blog
BMC DevOps Blog
Shift Left Testing: What, Why & How To Shift Left
Testing in DevOps: Introduction & Best Practices
What’s Testing as a Service? TaaS Explained
Beginner’s Guide to Test Automation Frameworks
These postings are my own and do not necessarily represent BMC’s position, strategies, or opinion.
See an error or have a suggestion? Please let us know by emailing
Web performance: How to load test – Stackify
Website owners commonly ask why they need a website performance load tester. Throughout web history, some extremely popular sites have had their fair share of serious downtimes. Either they get massive traffic volumes, or their website simply crashes. Thus, web performance load tester services check the application’s ability to perform under anticipated user loads.
Online presence requires site owners to identify performance bottlenecks before a website goes live to ensure optimal system performance. Here are some real events that will serve as our foundation in getting the gist of load testing:
The Macy’s website and mobile app crashed due to heavy traffic loads during Black Friday of 2016. As one of the largest US department store chains, it was unfortunate that Macy’s online portals crashed under Black Friday loads with its move to do business online. This unavailability resulted in unsatisfied customers and massive backlash on social media.
After the 2016 US election, the Canadian Immigration website crashed due to a huge traffic volume of Americans looking to move to Canada.
Encyclopedia Britannica gave free access to their online database. It turned out to be disastrous as the website failed to keep up with the onslaught of visitors.
Indeed, many websites suffer delayed load times due to heavy traffic. Not only that, but they also suffer revenue loss. According to Neil Patel, “If an e-commerce site is making $100, 000 per day, a one-second page delay may cost $2. 5 million in lost sales annually. ”
Therefore, there is a demand for developers to create a balance between development and testing. It requires strategies and tools to perform proper load testing practices.
This is where Application Performance Management (APM) solutions like Retrace come into play. Retrace by Stackify is a well-rounded APM that allows you to deploy with confidence. It doesn’t only focus on load testing but caters to the overall health of your website or your web app.
Want to know more? Try your FREE, 14 day Retrace trial today!
What is Load Testing?
Load testing is part of performance testing. Its objective is to provide confidence in the system with its reliability and performance. Bottlenecks are identified under heavy user stress scenarios before they occur in a production environment. Therefore, load testing not only provides excellent protection against poor performance but also accommodates complementary strategies.
It is a type of non-functional testing in the field of Software Engineering that determines how the website application or websites behave while being accessed by multiple users simultaneously. Also, most load testing practices are commonly used for web-based applications.
Overall, load testing works to identify the following:
The maximum operating capacity of the websiteThe current website infrastructure is sufficient to run in the actual environmentSustainability of the website or web app concerning peak user loadThe number of concurrent users that the app or site can supportScalability feature to allow more users’ accessibility
Goals, Strategies, Prerequisites, and Guidelines
“When to load test a website? ”
Developers are often asked by business owners this simple yet tricky question. Load testing is not just for Quality Assurance compliance as it is also a critical part of performance testing.
The answer is that load testing should be part of the development, and it will always be around as owners continuously scale their web presence.
On the other hand, for those who already have existing websites with issues about the website’s availability and scalability, the best approach is to perform load testing first. Also, when you have a small number of users, consider load testing as the initial step.
Goals of Load Testing
In website development, the goal of load testing is to identify the following problems before moving it into production or going live.
Measures the response time for each the performance of system components under various sesses the performance of database components under different lculates the response time between the client and the termines if there are software design if there are server configuration issues in web server, application server, database server, termines if there are hardware limitation issues like CPU maximization, memory limitations, network bottleneck, whether the system needs to be fine-tuned or needs hardware and software modification.
Strategies of load Testing:
Load testing comes in different variants. Here are some ways to perform it:
Manual Load Testing
This type of load testing is mostly done by users and doesn’t produce repeatable results. It is not conclusive measurable levels of load testing and a complicated process to coordinate. Users often use the concept of time study but it doesn’t reflect the overall status of the website.
In house developed load testing tools
It is more on a custom load tester when an organization sees the need for load testing.
Open source load testing tools
For website owners who are on a tight budget, there are several load testing tools available as open-source. These are free of charge but may slightly differ in terms of features and capabilities compared to their paid counterparts.
Enterprise-class load testing tools
For extremely huge companies with a global audience, this type of testing is ideal. It has a capture or playback facility and simulates a large number of web users.
Prerequisites of load testing
Response time is the fundamental metric for load testing. However, there are other prerequisites to consider. So before you begin, you must determine that:
There is an initial quantitative measurement of response time. Meaning, it is already measured and is the relevance between the response time and the transaction. For example, generating a PDF file compared to loading an image will have a large difference in response time. The response time is justifiable, realistic, achievable, and measurable (using a tool or stopwatch for manual testing).
Guidelines for load testing
Too often, guidelines for load testing are only exclusive for software testers. However, developers must also know that:
Load testing should be part of the software development plan. For every use case scenario, there should be a consistent and realistic number of consistency of response time over the elapsed period is should be various test runs, and comparisons are well documented.
How to Perform Load Testing?
In load testing, the first thing to decide is what to test. You may start with your critical services. This way, you get an idea of how your most valuable services affect your business. Also, work on the most frequent user journey and assess its most significant risks.
This information is just an initial step on how load testing works. It is either simple or complex depending on the features of the site or web app.
Here are some steps on how to perform load testing:
Create a dedicated test environment for load termine the load test termine load testing transactions for an epare data for each edict the number of users that will access the termine connection speeds as users are connected via wired or the different browsers and operating systems used by the users. Check all the server’s configuration like web, application, and DB the scenario execution, monitor, and collect various metrics. Analyze the results and create performance the system and repeat testing as required.
This is a straightforward list that applies to all. Now, let’s have an example with an e-commerce website.
Mostly, e-commerce websites invest heavily in advertising campaigns but fail in load performance testing. Since this is an on-demand site, focus on testing the performance of your backend requests. Also, consider the two most fundamental aspects that are often present in most web performance load tester services: server response time and the number of returned errors.
A load test simulation on an e-commerce site using hundreds of concurrent users could validate that:
The server doesn’t respond with is an average response time for a certain percentage of is an average response time for downloading images.
Furthermore, with all the steps in performing load testing, consider these three vital aspects to have a successful load testing process.
Ensure that test cases are well-defined. Test cases follow the concept of having test inputs, execution conditions, and expected results. It has a specific objective, such as to execute a particular program path or to verify compliance with a specific requirement.
Test cases are part of test plans that simulate users’ behaviors. It is done using virtual users on emulators, or it may involve using real users with different physical devices. They are significant as they allow website owners to see how their sites or web apps perform under virtually realistic conditions.
The load environment plays a critical role in load testing. Hence, consider even the smallest hardware configuration differences as it can have a big impact on the test results.
To have an ideal environment, ensure proper assessment of your hardware limits. It can help you with determining possible bottlenecks ahead of time. Although no test environment will ever exactly replicate your production, ensure to get things as accurate as possible.
Increment Load Testing
Load testing takes time, and the best approach is to run the load test incrementally. You don’t want to test everything at first. Instead, start with a small number of distributed users and then scale up slowly. It will help you to identify the bottlenecks better. Establish the time and location that contributes to loading problems or when the system crashes.
It is a looping process, and you should perform analytics after each iteration. Fix the bottlenecks and move on to the next test case.
Load Testing Tools
The success of your load test depends on the strategies and the kind of tools you choose. To achieve best-in-class website monitoring and load testing tools, try Stackify’s products!
For example, take a look at how and ROC Commerce stay ahead with Retrace. It provides optics on how the system responds to peak traffic loads and how APMs help in knowing about the issues before they strike. Using this tool offers a proactive rather than a reactive approach. It is good for the business and ultimately leads to better performance and satisfied customers.
Yet, the dilemma of choosing the right tool is daunting as the market has lots of options. As a tip, it would be better to choose a on-demand, easy to learn, and customizable tool to effectively address the required load testing.
Let’s have a look at the top 10 performance testing tools that also caters load testing:
ReadyAPI is a REST and SOAP API functional testing tool. It enables software developers, QA engineers, and manual testers to work together to create, maintain, and execute complex end-to-end API tests in their respective CI/CD, from Apache, is a load and performance testing tool that caters to different Application Testing Suite is an impressive testing tool that not only provides load testing but gives a complete performance testing Focus LoadRunner is formerly owned by HP and was known as HP LoadRunner. It is a load and performance testing tool that simulates thousands of users and provides in-depth oLoad is a load and performance testing tool that focuses on ogress Test Studio is an easy-to-use Web Automation tool on the market. Test Studio IDE is an innovative and easy-to-use tool to gather system performance and stability. SmartBear LoadComplete is a complete testing tool for web applications, including, Ajax, Flash/Flex, and Atest, from Parasoft, is a load and performance testing tool that is used for APIs and API-driven is a software testing platform that allows users to perform web regression testing. It works well with web, desktop, and mobile applications. Its features include playback of tests, test script editing, and data-driven testing. WebLOAD from RadView Software is an enterprise-class load and performance testing tool that offers scalable verification of web and mobile applications.
Pros and Cons
While load testing is necessary for online presence, it also has some challenges to consider. Here are the advantages and challenges of load testing:
It identifies performance bottlenecks before productionImproves scalability of the systemMinimizes risk related to system downtimeReduces the costs of failureIncreases customer satisfaction
It needs programming knowledge to execute load testing toolsLoad testing tools are expensive as pricing depends on the number of users supported
Always keep in mind your end-users
When conducting or planning load testing, always consider your end-users. They’re the bread and butter of your online presence. Without your site visitors and online customers, there will be no revenue. Hence, construct your website performance monitoring plan and testing strategies that keep the end-user experience at the forefront.
Load testing doesn’t end after each load test. Each result is deeply analyzed and compared against the previously identified metrics. Also, ensure that it works towards the business goals and aligns with the business objectives.
Overall, the purpose of load testing is to provide a top-notch user experience. Thus, your happy customers should be returning to your website and engaging with your brand, products, and services.
About the Author Latest Posts
What is Load Testing? How It Works, Tools, Tutorials, and More
Load testing is a type of performance testing that simulates a real-world load on any software, application, or website. Without it, your application could fail miserably in real-world conditions. That’s why we build tools like Retrace to help you monitor application performance and fix bugs before your code ever gets to production. Load testing examines how the system behaves during normal and high loads and determines if a system, piece of software, or computing device can handle high loads given a high demand of end-users. This tool is typically applied when a software development project nears completion.
In this article, you will learn:
how to load test,
load testing vs stress testing,
load testing software and tools,
benefits and examples,
and best practices
How it Works
How to load test? A load test can be done with end-to-end IT systems or smaller components like database servers or firewalls. It measures the speed or capacity of the system or component through transaction response time. When the system components dramatically extend response times or become unstable, the system is likely to have reached its maximum operating capacity. When this happens, the bottlenecks should be identified and solutions provided.
Performance Testing: Load Testing vs. Stress Testing
There is not much difference between load testing and stress testing, which is the reason why they are often confused with each other. Load testing and stress testing are both subsets of performance testing. Performance testing aims to examine system behavior and performance. Specifically, it monitors the response time, scalability, speed, and resource utilization of the software and infrastructure.
So how are the two different from each other? Load testing checks how the systems behave under normal or peak load conditions. Stress testing, on the other hand, is applied to check how the system behaves beyond normal or peak load conditions and how it responds when returning to normal loads.
Load Testing Tools
It’s important to choose a tool that best fits your business needs. Stackify Retrace helped stay ahead of its competitors through Application Performance Management.
There are a lot of load testing tools you’ll find in the market, but not all of them are the perfect fit to help your business succeed. Examples of these load tester software and tools are WebLOAD, LoadView, and Loadrunner.
WebLOAD works on any internet application using Ajax, NET, Oracle Forms, HTML5, and other technologies. LoadView measures performance in real browsers (not headless phantom browsers). Lastly, LoadRunner can manage thousands of users at the same time. For a comprehensive list of many of the tools available today, check out our list of 50 load testing tools.
Possible Use Cases and Examples
Below are a few of the many possible use cases:
Airline Website During Promotion Period. Evaluating an airline’s website that will be launching a flight promotion offer and is expecting 10, 000+ users at a time.
Government Web Portal. Evaluating a website of government agencies, particularly during the filing date of income tax returns when traffic will spike.
Running numerous concurrent requests on a server, thus, subjecting the server to a massive volume of traffic.
The nonstop transfer of multiple files to and from a hard disk. This could take the form of measuring the speed of a laptop with the transfer of 8GB-15GB files to and from a laptop with speeds of 1 Mbps.
Downloading a huge volume of large files from a company website to test performance.
Requesting various jobs on printers in a queue simultaneously.
Benefits of Load Testing
Benefits include the discovery of bottlenecks before production, scalability, reduction of system downtime, improved customer satisfaction, and reduced failure costs. Specifically:
Discovering bottlenecks before deployment. Evaluating a piece of software or a website before deployment can highlight bottlenecks, allowing them to be addressed before they incur large real-world costs.
Enhance the scalability of a system. It can help identify the limit of an application’s operating capacity. This can aid in determining infrastructure needs as the system scales upward.
Reduced risk for system downtime. It can be used to ferret out scenarios that can cause a system to fail. This makes it a great tool for finding solutions to high-traffic problems before they arise in the real world.
Improved customer satisfaction. If a website’s response times are short even as it scales up to a higher audience, one-time customers will be more apt to revisit.
Reduced failure cost. Identifying concerns at the earliest stage possible, especially before launch, decreases the cost of failures. By contrast, after-launch failures can incur exponentially greater costs.
Best Practices for Load Testing
The best tool and software is not all it takes for you to perform favorable load testing of your application. What you need most is knowledge of the best practices when load testing. Here are a few tried and tested practices:
Identify business goals. A strong understanding of future goals for scope and volume will draw clear guidelines to inform the process.
Determine key measures for the application and web performance. Agree on criteria to track. Some criteria include response times, throughput, resource utilization, maximum user load, and business performance metrics.
Choose a suitable tool. Select a tool that best caters to your needs. Some tools include but are not limited to WebLOAD, LoadView, and Loadrunner.
Create a test case. In writing a test case, make sure both positive and negative scenarios are taken into account. Test cases must be accurate and capable of being traced to requirements.
Understand your environment. Consider different types of deployments you might want to test. Create configurations similar to typical production. Test different system capacities like security, hardware, software, and networks.
Run tests incrementally. During these tests, the system will ultimately fail. One key goal is determining what volume results in failure, and spotlighting what fails first.
Always keep end-users in mind. The satisfaction of customers and site visitors is crucial to the achievement of business metrics. This plays into their willingness to revisit a site or re-access an application.
Load Testing Should Be on Your List
Performance testing is not something you can simply disregard, which also means load testing. This performance analysis process preps your system to be ready when it comes to real-world handling. If you launch your software without testing it beforehand, you’ll likely have missed a lot of issues. What’s worse, is that users are the ones who’ll find these issues, leaving a bad first impression and tarnishing your application’s reputation.
That is why you must highlight load testing in your software development process. But in addition to load testing, there are a lot of subsets in performance testing that you must know. For overall software performance management, look to application performance management software like Stackify Retrace.
Retrace proactively identifies various issues in QA and non-production stages of development. What’s more, is that it offers continuous improvement in the production environment. With Retrace, find issues and resolve them within your system before you introduce it to the market.
Start your FREE TRIAL now and enjoy the benefits of a developer-friendly, easy to use Application Management Tool (APM)!
About the Author Latest PostsWhat to Do About Java Memory Leaks: Tools, Fixes, and More – September 3, 2021What is Load Testing? How It Works, Tools, Tutorials, and More – February 5, and ROC Commerce stay ahead with Retrace – September 25, 2020Stackify’s New Pricing: Everything you need to know – September 9, 2020INNOVATORS VS COVID 19 Matt Watson, the CEO at Stackify, advises Entrepreneurs to focus on the things that make them happy, regardless if work is a giant dumpster fire – September 2, 2020
Frequently Asked Questions about how does load testing work for websites
How do you do a load test on a website?
Here are some steps on how to perform load testing:Create a dedicated test environment for load testing.Determine the load test scenarios.Determine load testing transactions for an application.Prepare data for each transaction.Predict the number of users that will access the system.More items…•Dec 18, 2020
What is website load testing?
Load testing is a type of performance testing that simulates a real-world load on any software, application, or website. … Load testing examines how the system behaves during normal and high loads and determines if a system, piece of software, or computing device can handle high loads given a high demand of end-users.Feb 5, 2021
How load testing is done?
As the best known and most commonly conducted type of performance testing, load testing involves applying ordinary stress to a software application or IT system to see if it can perform as intended under normal conditions.