Apache JMeter Properties Customization Guide

Ready to customize your JMeter properties? This guide will go over some of the most popular JMeter property customizations. 

Feel free to read along or skip to the section that interests you most.

Types of JMeter Properties

There are 2 types of properties that are in use by Apache JMeter which we recommend starting with: 

System Properties

JMeter Properties

System Properties

System properties are commonly used by any Java application. Since Apache JMeter is a purely Java application, it inherits all default properties and has the capabilities to access and override them. 

The properties class documentation is available on the Oracle website.

You can see a full set of predefined properties by using the BeanShell Sampler. 

1. Add a Thread Group to Test Plan.
2. Add a BeanShell Sampler to Thread Group as a child.
3. Add the following code to BeanShell Sampler in “Script” area:
   • System.getProperties().list(System.out);
4. See output in STDOUT for details.

There is a file in %JMETER_HOME%\bin folder called “system.properties” which is designed for overriding system properties. 

Sample Use Case: Changing the “file.encoding” Property

1. Obtain the default value of “file.encoding” property

- Option 1 – use the BeanShell Sampler and  System.getProperty(“file.encoding”)get “file.encoding” property value from STDOUT.

- Option 2 – use the Debug Sampler and View Results Tree 

• Add a Thread Group to Test Plan.
• Add Debug Sampler to Thread Group.
• Set “System properties” to “true”, others to “false.”
• Add View Results Tree listener to Test Plan.
• Run the test.
• Note the “file.encoding” property value in the Debug Sampler “Response Data.”

- Option 3 – use JMeter __P or __property function.

• Add a Thread Group to Test Plan.
• Add a HTTP Request Sampler with the following:
  • Server name - google.com.
  • Path - /
  • Parameters: Name:  q, Value: ${__P(file.encoding,)} 
• Add View Results Tree Listener.
• Run the test.
• Note the characters after /?q= in “Request” tab of View Results Tree listener.

- Option 1 – Command line argument –Dpropertyname=propertyvalue or invoke your JMeter startup script with “-Dfile.encoding=UTF8”  parameter

- Option 2 – Add “file.encoding=UTF-8” (without quotes) anywhere to “system.properties” file

Start or Restart JMeter and check “file.encoding” property with any of methods listed above. 

Both options are available on BlazeMeter: 

- Command line way – see Advanced Test Properties -> Additional JMeter Console Command Line Arguments and Additional JMeterEngine Command Line Arguments

- system.properties way – “system.properties” override file can be uploaded via Files interface 

JMeter Properties

JMeter Properties are like System Properties and are widely used in advanced JMeter scripting. They are used for passing data between thread groups or storing something more permanent where JMeter Variables cannot be used.

Pre-defined properties live in the “jmeter.properties” file; it provides rather good reference on what they’re for. 

The default list can be viewed in several ways: 

1. By reading “jmeter.properties” file using any text viewer tool

2. Listing via BeanShells script. Beanshell sampler, post- and pre- processors provide “props” object which can be used for getting/setting JMeter properties. The script code is as follows:

• props.list(System.out);

Basically, it returns all the System Properties PLUS JMeter properties remote_hosts, jmeter.version, etc. are JMeter Properties.

Almost any area of a JMeter application can be controlled by JMeter Properties starting from look and feel, timestamps, log levels, output file formats, and ending with low-level parameters of underlying libraries like Http Client timeouts, bind addresses, etc. used for different protocols connections. 

A good place to set or override these properties is the “user.properties” file. 

The values, specified in the “user.properties” file override the corresponding values from the “jmeter.properties” file. 

Sample Use Case: Changing “CookieManager.save.cookies” Property

Sometimes in the case of cookie-based authentication, it’s necessary to store HTTP cookies, which are coming from server under test in Set-Cookie header. This is to ensure that each thread is considered to be a unique user from server perspective.

By default the CookieManager.save.cookies property is set to “false” – this option won’t allow to save cookies for later usage. This example will demonstrate capability of overriding default behavior. 

Starting with next test plan structure: 

• HTTP Cookie Manager (all defaults).
• HTTP Request (all defaults, Server Name or IP – google.com).
• Debug Sampler (JMeter Variables – true, others – false).
• View Results Tree.

Now, execute the script and look into “Response Data” tab of Debug Sampler:

As we can see, no cookies were stored; however, they were set. Looking into “HTTP Request” -> Sample Result -> Response Headers – the following is present:

Restart JMeter and re-run the script. 

Now the cookies will be stored as a JMeter variable and can be iterated by For Each controller, stored to properties, etc. 

Assuming all above, there are two ways of overriding JMeter Properties:

1. Command-line argument –Jpropertyname=propertyvalue.

BlazeMeter supports all the above property overriding mechanisms and simplifies the setting custom properties process to a matter of seconds. In addition, the Real Time JMeter Properties Control feature during test execution enables you to play with any property and immediately see the impact in Load Report section.

Want to learn more about JMeter? Check out BlazeMeter University.

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