When your software development project is nearing completion, one crucial test is essential to assess its deployment readiness: load testing. This form of performance testing enables you to evaluate how your web application behaves under both normal and peak load conditions, including identifying its breaking point, if it occurs below the peak load condition. Essentially, load testing is employed to confirm that your web application meets the intended performance goals outlined in a service level agreement (SLA).
Given the increasing reliance of users on web applications to access products or services, load testing plays a pivotal role in validating your application's ability to function seamlessly under realistic load scenarios. Not only does load testing minimize the risk of software failure, but it also reduces the chances of users experiencing frustration due to application downtime, potentially leading them to abandon the application—impacting your company's financial bottom line significantly. According to Gartner, the average cost of network downtime for businesses is $5,600 per minute, translating to well over $300,000 per hour.
For those unfamiliar with load testing or preparing for their first one, this guide is a valuable resource. Below, we will outline how load testing operates, provide insights into successfully conducting a load test, and discuss various load testing tools you might consider.
What is load time?
Load testing is a critical process in software testing where the software's performance is evaluated under specific loads to observe its behavior during expected or heavy usage. This type of performance testing aims to assess the speed, scalability, and reliability of a system, providing valuable insights into its overall performance characteristics.
How does load testing work?
Load testing, facilitated by specialized testing software, involves applying a simulated "load" or demand on your web application to ensure its stability during operation. In the process of load testing, the testing software assesses your web application's capacity by measuring transaction response times. If your application exhibits extended response times or becomes unstable under a specific level of simulated traffic, it likely indicates that your software has reached its peak operating capacity. Addressing and implementing a solution for this bottleneck is crucial in such cases.
Load testing provides development teams with the ability to measure and analyze various aspects, including:
- Throughput rates: Especially those required to support peak load conditions.
- Resource utilization levels: Evaluating CPU and RAM performance.
- Load balancer performance: Ensuring efficient distribution of the traffic load.
- Concurrency issues: Identifying problems related to simultaneous user interactions.
- Software functionality errors: Investigating how the software behaves under different levels of load.
- Software design flaws: Discovering potential weaknesses in the application's architecture.
- User capacity: Determining the number of users the application can handle before breaking down.
Load testing is invaluable for developers as it helps them identify issues like system lag, slow page load times, or crashes that might occur when the application faces varying levels of traffic during production, rather than discovering these problems after the application has been launched. An example of load testing could be a tax preparation company evaluating their web application's performance before the peak income tax filing season, anticipating the traffic spikes it will experience.
When is the best time to do load testing?
Load tests should be conducted regularly as a proactive measure, with a particular emphasis before high-traffic events or following significant changes to your application architecture, system dependencies, or code algorithms.
A substantial 57% of organizations perform performance and/or load tests with each sprint, and an overwhelming 95% commit to annual testing. Only a minimal 5% of IT professionals admit to "never" running load or performance tests, underlining the widespread recognition of their importance in ensuring application reliability and performance.
Absolutely, load testing before high-traffic events is a crucial practice for companies and organizations. Such events can include:
- The Launch of a New Product or Service: Ensuring that the infrastructure can handle the influx of users eager to explore the new offering.
- Major Flash Sales like Black Friday: As these events often attract a massive surge in online shoppers, load testing is essential to prevent website crashes and maintain a seamless shopping experience.
- Ticket Onsales for Hyped Concerts or Events: Ticketing platforms experience intense demand during these periods, making load testing vital to handle the ticket-buying frenzy without disruptions.
- High-Profile Public Sector Registrations: Government websites dealing with registrations, especially during critical periods like elections or official announcements, must be load-tested to handle the surge in traffic efficiently.
- Large Marketing Campaigns or PR Appearances: Load testing is necessary to ensure that the increased traffic resulting from successful marketing efforts doesn't overwhelm the website, ensuring a positive user experience.
In essence, load testing before such high-traffic events is a proactive measure to guarantee that the services remain stable, responsive, and reliable, even under extreme loads. This helps in maintaining customer satisfaction and prevents potential revenue losses due to downtime or a poor user experience.
Absolutely, preparing for unexpected traffic spikes is equally important, even if your site doesn't have scheduled high-traffic events. Unexpected surges in traffic can occur due to various reasons, including:
- PR Appearances or Features in Major News Outlets: Positive media coverage or features in influential publications can drive a sudden influx of visitors to your website.
- Celebrity Endorsements or Mentions: When a celebrity promotes or mentions your brand, it can lead to a significant increase in website traffic.
- Viral Social Media Posts or Frontpage Exposure on Platforms like Reddit: A post going viral on social media platforms or making it to the front page of popular websites like Reddit can result in a massive surge in visitors, often referred to as the “Reddit hug of death” or the “Slashdot effect.”
Indeed, the load testing process is not a one-time task; it's iterative and requires careful planning and early initiation. Here's why starting early and being proactive is crucial:
Complex Iterative Process: Load testing is iterative. The first test might reveal a bottleneck.
Fixing it might expose another issue, and so on. Achieving the desired capacity or throughput often takes multiple iterations and adjustments. Starting early allows for thorough testing and refinement.
- Time Constraints: 38% of IT professionals find time to be a significant constraint in load testing. Initiating the process early provides ample time to identify issues, make necessary changes, and retest the application before deployment.
- Code Freeze Challenges: Many organizations implement code freezes before major sales events, making it crucial to complete testing and implement changes well in advance. Delaying load testing until it's too late could mean being unable to address critical issues before the event.
- Proactive Approach: Queue-it prioritizes reliability, availability, and performance under load. They conduct load tests whenever changes occur in design, architecture, or algorithms, or when new infrastructure is set up. Additionally, they perform load tests for client events with anticipated high traffic. This proactive approach ensures readiness for unexpected traffic spikes.
- Scheduled Automated Load Testing: Queue-it is working on developing scheduled automated load testing, which enables continuous monitoring and tracking of performance over time. Automated testing generates reports, allowing for proactive identification of performance trends and potential issues.
In summary, initiating load testing early, maintaining a proactive stance, and embracing an iterative approach are key strategies to ensure a web application's reliability and performance under varying loads, ultimately providing a seamless user experience.
Load Testing vs. Stress Testing
Absolutely, load testing and stress testing are essential components of the software performance testing process, each with distinct objectives in evaluating web application performance.
- Load Testing is focused on assessing how an application behaves under normal and peak load conditions. It involves simulating realistic user scenarios to measure the application's response times, throughput rates, and resource utilization levels. The primary goal is to ensure the application's stability and functionality within expected usage parameters.
- Stress Testing, on the other hand, goes a step further. It evaluates the application's behavior beyond its normal or peak load conditions. Stress testing involves pushing the application to its limits and even exceeding them to observe how it performs under extreme stress. This helps identify breaking points, bottlenecks, and potential weaknesses in the system. Stress tests also examine how the application recovers and behaves once the stress is reduced, providing insights into its resilience and recovery capabilities.
How do you perform a load test?
To perform a successful load test, it's crucial to follow a systematic approach and incorporate the right tools. Here are the steps you should follow:
- Identify Web Application Objectives: Begin by defining the scope and volume of your web application. Determine critical functionalities for testing, including response times, resource utilization levels, and maximum user load. Establish clear guidelines to inform the testing process based on these objectives.
- Outline User Journeys: Map out how users interact with your web application. Utilize data from application performance monitoring tools (APMs) if available. Focus on key application processes and performance metrics based on these user interactions. Understanding user behavior is essential for designing relevant and effective load tests.
- Select a Load Testing Tool: Choose a load testing tool that aligns with your requirements. Look for tools that are user-friendly, scalable, provide accurate results, and seamlessly integrate with your existing tools.
8 Essential Cloud-based Load Testing Tools
- Load View: LoadView offers a free stress-testing opportunity by providing $20 in credits for on-demand testing. This credit allows users to conduct a couple of tests with default parameters at no cost. If you find the service beneficial, you have the option to continue using it on-demand by paying for each test individually. Alternatively, you can choose to subscribe to a monthly or annual plan for more regular and consistent stress testing of your website. This flexible approach enables users to explore the service without an initial financial commitment and tailor their usage based on their specific testing needs.
- Flood IO: Flood IO is a cloud-based performance testing service that lets you upload JMeter or Selenium test plans or create tests using their GUI. The free plan offers unlimited concurrent users with a few limitations, making it a popular choice for diverse testing needs.
- Loader: Loader.io provides a free account option allowing a one-minute load test with 1000 user requests, making it convenient for testing against a substantial user load. The service offers configuration options including request parameters, error thresholds, and HTTP methods, allowing users to tailor their tests according to their specific needs.
- Blazemeter: BlazeMeter is a must-try for JMeter enthusiasts. It offers effortless scenario property configuration and allows testing from various global locations. The free account allows load tests with up to 50 users. After the test, users receive a detailed summary, load report, monitoring, logs, and error analysis, enhancing the testing experience.
- OctoPerf: OctoPerf is a SaaS-based performance testing tool that utilizes JMeter to test web, API, REST, and mobile applications. With OctoPerf, users can design, monitor, execute, and analyze website performance directly through a web browser, simplifying the testing process.
- K6: You can scale for up to 100,000 concurrent users and execute tests using CLI, CI pipelines, or web GUI. You can initiate a test from 17 geolocations. Test results are easy to understand, and you can filter them for in-depth visualization.
- LoadNinja: LoadNinja is a user-friendly SaaS load testing tool that significantly reduces web and API testing time, allowing users to complete tests in minutes instead of hours. It's designed for individuals with limited or no coding experience, making it accessible to a broader range of users.
- Gatling: Gatling is a continuous testing tool that seamlessly integrates with the development process. It specializes in simulating heavy traffic to conduct extensive stress testing, ensuring your application or website can handle extreme loads in real-time scenarios.
What should you do when you fail a load test?
When your load test fails, the initial step is to analyze the results, identify the bottleneck(s) hindering performance, and address them. This may involve actions such as:
- Analyze Results: Thoroughly examine the test results to identify performance bottlenecks and areas of failure.
- Identify Bottlenecks: Pinpoint specific bottlenecks, whether in code, server resources, third-party services, or elsewhere.
- Address Bad Code: Fix any inefficient or problematic code that affects performance.
- Optimize Resources: Ensure server resources (CPU, memory, etc.) are properly allocated and optimized.
- Review Third-Party Services: Contact third-party service providers to enhance their throughput or consider alternatives.
- Toggle Intensive Features: Temporarily disable or optimize performance-intensive features.
- Optimize CDN: Review and optimize your Content Delivery Network (CDN) settings.
- Implement Auto Scaling: Set up auto scaling to dynamically adjust resources based on demand.
- Retest: After making changes, rerun the load test to assess improvements.
- Continuous Monitoring: Implement continuous monitoring and regular load testing to prevent future issues and ensure ongoing performance optimization.
Handling high traffic events presents several common external challenges, including:
- Sudden Traffic Spikes: Unpredictable events, promotions, or social media mentions can lead to rapid traffic increases.
- Limited Inventory: Events with limited goods, like ticket sales, may face challenges related to fair allocation and potential overselling.
- Third-Party Service Dependencies: Reliance on third-party services (payment processors, APIs) can lead to bottlenecks if these services face issues.
- Geographical Variability: Websites serving a global audience must handle traffic from diverse geographical locations, each with varying network conditions.
- Network Issues: DDoS attacks or network congestion can disrupt traffic flow and cause website downtime.
- Device and Browser Diversity: Visitors may use a wide array of devices and browsers, each with different performance capabilities, adding complexity to handling traffic.
- Regulatory Compliance: Compliance requirements can affect how user data is handled, impacting site performance during high traffic events.
- Bot Attacks: Malicious bots can flood websites, causing server overload and disrupting user access.
Addressing these challenges requires strategic planning, robust infrastructure, and continuous monitoring to ensure smooth operations during high traffic periods.
If you’re facing these challenges handling high traffic events, there is another solution. It is quick and straightforward to implement, needing minimal optimization. It ensures a fair, dependable customer experience and safeguards your site or app against any level of load.
This solution is known as a Virtual Waiting Room.
A virtual waiting room provides control over a crucial aspect that other performance optimization methods cannot: managing traffic.
If you have a sale or registration event scheduled to start at a specific time, you can implement a scheduled waiting room. This waiting room holds early visitors on a countdown page and randomizes their entry, akin to a raffle, ensuring everyone has an equal chance. Subsequent visitors are added to the queue based on a first-in, first-out basis.
NetFUNNEL enables organizations to keep their website and applications online without outages. Virtual Waiting Rooms provide organizations with the means to manage their web traffic effectively, ensuring a fair and smooth user experience for their visitors. Along with the EUM (End-user monitoring) tool, you can prevent bots and abuse while enhancing protection against sudden traffic surge. NetFUNNEL empowers them to focus on core business strengths which involve delivering good-quality products & services to their visitors, ultimately improving user experience.