Locust installation and setup

Installation

To install Locust, follow the instructions at Locust Installation

• Create a directory for the Locust project
• Create a subdirectory for the source code
• Create a new Anaconda virtual Python environment. ( At the time of writing Python version 3.10 is the latest. )
  conda create -n locust python=3.10
• Activate the new virtual environment
  conda activate locust
• Install Locust
  pip3 install locust
• Check the success of the installation
  locust -V

Troubleshooting

If the check fails with the error message

ValueError: greenlet.greenlet size changed, may indicate binary incompatibility. Expected 152 from C header, got 40 from PyObject

Make sure you use the Anaconda virtual Python environment to avoid version conflicts between installed Python components.

Create your first test

See https://docs.locust.io/en/stable/quickstart.html for the Quick Start tutorial.

• Create the test file
  locustfile.py
• Specify the actions to be taken

import time
from locust import HttpUser, task, between

class QuickstartUser(HttpUser):
  wait_time = between(1, 5)

  @task(3)
  def view_items(self):
    # self.client.get(url + "/")
    self.client.get("/")

  @task
  def hello_world(self):
    # self.client.get(url + "/about")
    self.client.get("/about")


  def on_start(self):
    a = 0 # Just a placeholder, as every def has to have at least one executable instruction
    # No login is necessary for this site
    # self.client.post("/login", json={"username":"foo", "password":"bar"})

Starting Locust

• Open a terminal in the directory where the locustfile.py is located.
• Start Locust with
  locust -f locustfile.py
• Open the web UI at http://localhost:8089/
• Specify the number of concurrent users and the span rate of the users. Enter the URL of the site to be tested. IMPORTANT: Make sure there is no slash at the end of the URL, otherwise the generated URL will contain double slashes!!!
  
• Click the Start swarming button.

Changing the load test script

To make sure, Locust will execute the updated script

• Stop the Locust process in the terminal with CTRL-C
• Modify and save the locustfile.py file
• Start the Locust process with
  locust -f locustfile.py