Apache JMeter is a 100% pure Java open-source performance testing tool. It is widely used for web and API testing due to its zero license costs and extensibility.
JMeter Core Components
- Thread Group: Represents virtual user pools. Controls ramp-up and iteration duration.
- Samplers: Send requests to servers (HTTP Request, JDBC, SOAP, etc.).
- Listeners: Collect and display execution stats (View Results Tree, Summary Report).
- Assertions: Checkpoints to verify response content.
Best Practice
Never run high-volume load tests using the JMeter GUI. It consumes significant client-side memory, distorting response time results. Use CLI mode (`jmeter -n -t test.jmx -l results.jtl`) for execution.