Locust: Comprehensive Strategies for Load Test Execution

Posted on by

After setting up the Locust environment, it’s time to explore the different ways to run load tests. This guide will cover local executions, command-line runs, and distributed server configurations.

Locust load testing execution strategies qa debug

Local Execution with Web Interface

Preparing the Environment

  1. First, activate your virtual environment:
# Linux/Mac
source your-environment-name/bin/activate

# Windows
your-environment-name\Scripts\activate

2. Then, start Locust by running:

locust -f tests/main.py

3. Now, access the web interface at:
http://localhost:8089

Command-Line Execution

Essential Configuration Parameters

To run Locust in headless mode (without the web UI), use the following command:

locust -f tests/main.py --headless \
  -u 100 -r 10 \
  --run-time 5m \
  --host=https://example.com

Parameter Breakdown:

  • -u 100: Simulates 100 concurrent users
  • -r 10: Spawns 10 new users per second
  • --run-time 5m: Test duration of 5 minutes
  • --host: Specifies the target system URL

Distributed Testing: Master-Worker Configuration

Understanding Distributed Testing Architecture

For high-load scenarios, using a master-worker architecture ensures better scalability.

Step 1: Start the Master Machine

On the main server, execute:

locust -f tests/main.py --master \
  --master-bind-host=0.0.0.0 \
  --master-bind-port=5557

Step 2: Start Worker Machines

On each worker machine, connect to the master:

locust -f tests/main.py --worker \
  --master-host=MASTER_SERVER_IP \
  --master-port=5557

Advanced Distributed Configuration

Example of a Complete Setup

  • Master Server (192.168.1.100): bashCopyEditlocust -f tests/main.py --master \ --master-bind-host=0.0.0.0 \ --master-bind-port=5557 \ --web-host=0.0.0.0 \ --web-port=8089
  • First Worker (192.168.1.101): bashCopyEditlocust -f tests/main.py --worker \ --master-host=192.168.1.100 \ --master-port=5557
  • Second Worker (192.168.1.102): bashCopyEditlocust -f tests/main.py --worker \ --master-host=192.168.1.100 \ --master-port=5557

Key Considerations for Distributed Testing

Infrastructure Requirements

To ensure seamless execution, all servers must have:
✅ The same test script
✅ A compatible version of Locust
✅ Network access between master and workers
✅ The same Python version

Best Practices

To optimize performance:
✔️ Configure the firewall to allow communication
✔️ Monitor computing resources during execution
✔️ Run incremental tests before large-scale execution
✔️ Validate network configurations

Generating Reports

Saving Test Results

To export test statistics to a CSV file, use:

locust -f tests/main.py --csv=test-report \
  --headless -u 100 -r 10 --run-time 5m

Generated Files:

📂 test-report_stats.csv: General test statistics
📂 test-report_stats_history.csv: Historical test data

Conclusion

Mastering different Locust execution strategies allows for robust and scalable load testing.

Next Steps:

✅ Automate test execution
✅ Integrate with CI/CD tools
✅ Develop more complex test scripts