JMeter Switch Controller or How to Run a sampler with a certain Percentage

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Context:

• you want to run different parts of a Test plan a different rate
• you want to be sure one and only one of the samples occur

Example:

• You want to run 4 types of searches:
  • Search by Last Name
  • Search by Mail
  • Search by Phone Number
  • Search by Card Number
• You want to use the search result (so be sure it executed once)

How-To:

Create a Test Plan like this one:

• Important parts are:
  • BeanShell Sampler
  • SwitchController which uses ${SWITCH_VALUE} as switch condition
  • 4 samplers (could be transaction controller or any other sampler)

• Content of BeanShell Sampler are the following:

// Array of values that contain the % repartition we want
int[] values = (int[])vars.getObject("RANDOM_VALUES");
if(values==null) {
	values = new int[] {0,1,2,3,2,3,1,3,2,3};
	vars.putObject("RANDOM_VALUES",values);
}
// Increment that will be used in SwitchController value will be between 0 and 3
// because there are 4 samplers
Integer increment = (Integer)vars.getObject("INCREMENT");
if(increment==null) {
	increment = Integer.valueOf(0);
} else {
	increment = Integer.valueOf((increment.intValue()+1)%10);	
}
vars.put("SWITCH_VALUE", new Integer(values[increment.intValue()]).toString());
vars.putObject("INCREMENT", increment);

• Note the following:
  • BeanShell Sampler generates SWITCH_VALUE, a number between 0 and 3 (because there are 4 samples)
  • The percentages are held in RANDOM_VALUES array, note we have:
    • 10% of 0
    • 20% of 1
    • 30% of 2
    • 40% of 3
  • The generated number will decide which sampler is ran:
    • If 0 is generated, the first one will be run (Sampler-10%)
    • If 1 is generated, the second one will be run (Sampler-20%)
    • If 2 is generated, the third one will be run (Sampler-30%)
    • If 3 is generated, the fourth one will be run (Sampler-40%)

That's it.

Result:

2 VUs with Loop of 50:

Want to Learn more?:

• Read our other articles on Load Testing
• Wiki JMeter
• JMeter Component Reference
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Author:

Philippe Mouawad