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Load testing with Locust – A modern tool for quality assurance

Saad Shaikh - Associate Data Engineer
Saad Shaikh

November 26

 Data Science Dojo is offering Locust for FREE on Azure Marketplace packaged with pre-configured Python interpreter and Locust web server for load testing. 


Why and when do we perform testing? 

Testing is an evaluation and confirmation that a software application or product performs as intended. The purpose of testing is to determine whether the application satisfies business requirements and whether the product is market ready. Applications can be subjected to automated testing to see if they meet the demands. Scripted sequences are used in this method of software testing, and testing tools carry them out. 

The merits of automated testing are: 

  • Bugs can be avoided 
  • Development costs can be reduced 
  • Performance can be improved till requirement 
  • Application quality can be enhanced 
  • Development time can be saved 

Testing is usually the last phase of the SDLC (Software Development Life Cycle)  

What is load testing and why choose Locust?  

Performance testing is one of several types of software testing. Load testing is an example of performance testing to evaluate performance under real-life load conditions. It involves the following stages: 

  • Define crucial metrics and scenarios 
  • Plan the test load model 
  • Write test scenarios 
  • Execute test by swarming load 
  • Analyze the test results 

It is a modern load testing framework. The major reason senior testers prefer it over other tools like JMeter is because it uses an event-based approach for testing rather than thread based. This results in less consumption of resources and thus saves costs. 

Pro Tip: Join our 6-months instructor-led Data Science Bootcamp to master data science skills 

Challenges faced by QA teams  

Before such feasible testing tools, the job of testing teams was not much easier as it is now. Swarming a large number of users to direct as a load on a website was expensive and time-consuming.  

Apart from this, monitoring the testing process in real time was not prevalent either. Complete analytics were usually drawn after the whole testing process concludes, which again required patience. 

The testers needed a platform through which they can evaluate quality of product and its compliance with the specified requirements under different loads without the prolonged wait and high expense. 

Working of Locust 

Locust is an open-source web-based load testing tool. It is based on python and is used to evaluate the functionality and behavior of the web application. For the quality assurance process in any business, load testing is an extremely critical element to assure that the website remains up during traffic influx as it will eventually contribute to the success of the company. Through Locust, web testers can determine the potential of the website to withstand the number of concurrent users. With the power of python, you can develop a set of test scenarios and functions that imitate many users and can observe performance charts on web UI. 


Locust file
Figure 1: A sample locustfile.py 


The self.client.get function points to the pages of a website that you want to target. You can find this code file and further breakdown here. The host domain, users and the spawn rate for the load testing are supplied at the web interface. After running the locust command, the web server is started at 8089. 


locust web interface
Figure 2: Locust web interface


It also allows you to capture different metrics during the testing process in real-time. 


graphs with metrics
Figure 3: Graphs with metrics visualizations


Key characteristics of Locust 


  • An interactive user-friendly web UI is started after executing the file through which you can perform load testing 
  • Locust is an open-source load-testing tool. It is extremely useful for web app testers, QA teams and software testing managers 
  • You can capture various metrics like response time, visualized in charts in real-time as the testing occurs 
  • Achieve increased throughput and high availability by writing test codes in pre-configured python interpreter 
  • You can easily scale up the number of users for extensive production level load testing of web applications 


What Data Science Dojo provides 


Locust instance packaged by Data Science Dojo comes with a pre-configured python interpreter to write test files, and a Locust web UI server to generate the desired amount of load at specific rates without the burden of installation.  

Features included in this offer:  

  • VM configured with Locust application which can start a web server with rich UX/UI 
  • Provides several interactive metrics graphs to visualize the testing results 
  • Provides real-time monitoring support 
  • Ability to download requests statistics, failures, exceptions, and test reports 
  • Feature to swarm multiple users at the desired spawn rate 
  • Support for python language to write complex workflows 
  • Utilizes event-based approach to use fewer resources 

Through Locust, load testing has been easier than ever. It has saved time and cost for businesses as QA engineers and web testers can perform testing now with few clicks and few lines of easy code. 





Locust can be used to test any web application. By swarming many clients spawning at a specific rate, the functionality of a website can be assured that it can manage concurrent users. To achieve extensive load testing, you can use multi-cores on Azure Virtual Machine. Also, the Its web interface calculates metrics for every test run and visualizes them as well. This might slow down the server if you have hundreds upon hundreds of active test units requesting multiple pages. The CPU and RAM usage may also be affected but through Azure Virtual Machine this problem is taken care of. 

At Data Science Dojo, we deliver data science education, consulting, and technical services to increase the power of data. We are adding a free Locust application dedicated specifically for testing operations on Azure Marketplace. Now hurry up install this offer by Data Science Dojo, your ideal companion in your journey to learn data science!  


Click on the button below to head over to the Azure Marketplace and deploy Locust for FREE by clicking on “Try now” 

CTA - Try now 

Note: You will have to sign up to Azure, for free, if you do not have an existing account. 

Saad Shaikh - Associate Data Engineer
Written by Saad Shaikh

He is an Associate Data Engineer at Data Science Dojo. He focuses mostly on Azure Cloud services as he develops Azure Marketplace offers and has published many of them, belonging to various categories.

Interested in writing for us? Apply here: Submit your guest post with us
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