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JMeter Functions

JMeter functions can be referred as special values that can populate fields of any Sampler or other element in a test tree.

Syntax of a function in JMeter:

Here "__functionName" matches the name of a function and Parentheses surround the parameters sent to the function.

If a function parameter contains a comma then be sure to escape this with "\", otherwise JMeter will treat it as a parameter delimiter.

For example:

List of Functions

Type of function	Name	Comment
Information	threadNum	Get thread number.
Information	samplerName	Get the sampler name (label).
Information	log	Log (or display) a message (and return the value).
Information	machineName	Get the local machine name.
Input	StringFromFile	Read a line from a file.
Input	FileToString	Read an entire file.
Input	CSVRead	Read from CSV delimited file.
Input	XPath	Use an XPath expression to read from a file.
Calculation	Counter	Generate an incrementing number.
Calculation	intSum	Add int numbers.
Calculation	longSum	Add long numbers.
Calculation	Random	Generate a random number.
Calculation	RandomString	Generate a random string.
Scripting	BeanShell	Run a BeanShell script.
Scripting	javaScript	Process JavaScript (Mozilla Rhino).
Scripting	jexl, jexl2	Evaluate a Commons Jexl expression.
Properties	Property	Read a property.
Properties	P	Read a property (shorthand method).
Variables	Split	Split a string into variables.
Variables	V	Evaluate a variable name.
Variables	eval	Evaluate a variable expression.
String	regexFunction	Parse previous response using a regular expression.
String	escapeOroRegexpChars	Quote meta chars used by ORO regular expression.
String	Char	Generate Unicode char values from a list of numbers.
String	Unescape	Process strings containing Java escapes (e.g. \n & \t).
String	unescapeHtml	Decode HTML-encoded strings.
String	escapeHtml	Encode strings using HTML encoding.
String	TestPlanName	Return name of current test plan.

Note: JMeter Functions and Variables are always case sensitive.

Let us consider an example of Log Function to understand the use of functions in JMeter.

Syntax of JMeter Log Function:

First, we will create a simple test plan with HTTP request sampler.

Create JMeter Test Plan

Go to your JMeterbin folder and double click on the Apache JMeter ".jar" file to launch JMeter interface.
Select the test plan node and right click on the selected item.
Mouse hover on "Add" option then elements list will be displayed.
Select Threads (Users) > Thread Group.
Rename this Thread Group as Thread Group 1.

Add Sampler

We have to add a HTTP request sampler in our Thread Group.

Select the Thread Group and right click on the selected item.
Mouse hover on "Add" option then elements list will be displayed.
Select Sampler > HTTP request option.
It will add an empty HTTP Request Sampler.

Configure the fields of HTTP Request Sampler as

Name - HTTP Request Sampler 1.
Server Name or IP - In our case, web server name will be www.w3cschoool.com.
Protocol - This field is left unaltered.
Path - We will write it as "/" (slash). It indicates that we want the root page of the server.

Now, copy the entire Thread Group 1 and paste it three times in our test plan.

Rename the other thread groups as Thread Group 2 and Thread Group 3 respectively.
Rename the other samplers as HTTP Request 2 and HTTP Request 3 respectively.

The following image shows the directory structure of our test plan.

Add Listener

Select the Test Plan node and right click on the selected item.
Mouse hover on "Add" option then elements list will be displayed.
Select Listener > Summary Report.

Save and Execute Test Plan

Click on File > Save Test Plan as.
Save the entire test plan as Function_test.jmx

Click on Run > Start to execute the test plan.

Verify the Output

Hence, we have successfully executed our test plan. Now, we will use the log function as name for the first HTTP Request Sampler.

Click on Run > Start to execute the test plan.

You can see that the Log Function has printed "Hello World" instead of complete sampler name. Let us consider one more example of Time Function which we will use again as name for second HTTP Sampler.

Syntax for time function:

Click on Run > Start to execute the test plan.

You can see that the Time Function has printed the exact time and date instead of complete sampler name.

To get more knowledge of JMeter Functions and their usage, refer the document release by Apache JMeter provided under the link: http://jmeter.apache.org/usermanual/functions.html

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