Performance Testingwith JMeter

Adam Goucher

http://adam.goucher.ca

adam_goucher@hotmail.com

Lecture Objective

Give students an introduction to performance testing concepts and implementation using JMeter.

Definitions

Performance Testing

Performance testing determines or validates the speed of the AUT (X per T)

Load Testing

Load testing identifies the maximum operating capacity of an application as well as any bottlenecks that might interfere with its operating at capacity

(Or, when does it blow up?)

Stress Testing

Stress testing is focused on determining an application’s robustness, availability, and reliability under extreme conditions

• heavy loads

• high concurrency

• limited computational resources

Scalability

Scalability testing determines or validates whether adding another Y resource (database, memory, disk, CPU, etc) increases speed of X proportionally

Pre-testing Activities

Design Review

The cheapest performance issues to address are ones that are never put into the code.

Testers should review the application design to see if there are any obvious potential performance problems.

Environment Prep - Network

Performance testing is often a network intensive activity which can affect others in the organization

Testing should be done on a separate, segregated network.

Environment Prep - Hardware

Depending on what your goals are for your testing, different hardware is appropriate for both the AUT and load generators.

Testers should acquire and configure the correct hardware.

Environment Prep - Software

Generating load is not as easy as it sounds.

Testers should acquire or create load generators and configure them for their desired goal

Mission

Performance testing without a Mission is just throwing load at a server to see what is going to happen.

Testers should determine Why they are doing their testing.

Audience

Determining who you are generating numbers for, will largely dictate what you do

• Development

• Marketing

• Operations

Metrics

Performance testing is all about numbers and metrics.

Testers should determine which metrics they are concerned about and how to get them.

Give Warning

Let anyone who might be affected by your testing advance warning.

Generic Testing Steps

1. Create / Record Test

2. Add measurement hooks

3. Data drive script

4. Add logging

5. Build workload profile

6. Execute test

JMeter

JMeter

JMeter is a free, open-source performance measurement tool written in Java

Thread Groups

The Thread Group is the basic element of a JMeter Test Plan

Each thread represents a user setting a thread group to 1000 simulates 1000 users

Samplers

Samplers do the actual work in JMeter and interact with the server you are loading

There are a number Samplers in JMeter by default. For web testing, use ‘HTTP Request'

Listeners

The information produced by Samplers is consumed by Listeners

Popular listeners are:

• Graph Results

• View Results Tree

• Simple Data Writer

Logic Controllers

Logic Controllers determine the order that Samplers are processed

More complex scripts will make use of• Loops• Interleave• Random• If

Assertions

A test isn’t a test unless it checks something. Assertions are what do the checking

For web applications, these are the useful ones

• Response• Duration• HTML Assertion

Configuration Elements

Configuration Elements set default values for other parts of the Test Plan as well as configure variables

• CSV Data Set Config allows you do to DDT within JMeter

• HTTP Cookie Manager will automatically intercept and sent cookies with requests

• HTTP Request Defaults saves you time when doing lots of HTTP Samplers

Variables

In JMeter, you can reference variables as such

${VARIABLE}

Batch

JMeter can run in a non-gui mode to save resources on the load generating machines

Recording

There is a way to record tests (as in LoadRunner) but I find it easier to build scripts one element at a time