Introduction to JMETER and Performance Testing

 JMeter

• JMeter is an open-source load-testing tool used by developers and performance engineers to measure the performance of web applications.
• It can be used to simulate a heavy load on a server, network or object to test its strength or to analyze overall performance under different load types.
• Measure the application performance and response times.

Test Plan: (Top level directory)

• A complete test plan will consist of one or more Thread Groups, logic controllers, sample-generating controllers, Listeners, Timers, Assertions, and configuration elements.

1. Adding elements.
2. Removing elements.
3. Saving test plans.
4. Running test plans.
5. Stopping a test plan(immediate shutdown), Shutdown(graceful shutdown).
6. Logging the info and errors.

Important components of a Test Plan:

1. Thread Group
2. Listeners
3. Timers
4. Assertions

Thread Group:

• The beginning point of any test plan.
• The thread group element controls the number of threads Jmeter will use to execute your test.
• All controllers and samplers must be under a thread group.

Main properties of thread group:

• Set the number of threads (simulation of a number of concurrent users).
• Set the ramp-up period (time taken to threads up and running = ramp-up period/Thread 

Samplers:

• Samplers send requests to the server and collect the response.
• JMeter supports several types of samplers, including HTTP, FTP, JDBC, LDAP and SOAP.

Listeners:

• Listeners can be added to test plans or thread group level.
• Listeners provide a way to view the results of a test in JMeter.
• Listener options - Graph result, view results tree, view result table, aggregate report, aggregate graph, response time graph.