threadNum is an in-build function of Apache JMeter and its type is ‘Information’, which provides specific details about the thread. By the way, JMeter in-build functions are divided into eight categories which are:
- Information
- Input
- Calculation
- Formatting
- Scripting
- Properties
- Variables
- Strings
Syntax: ${__threadNum}
Type: Information
Purpose: To get the Thread Number under a Thread Group. If there are multiple thread groups under the same test plan then threadNum() will return the separate thread number concerning each thread group. Example: If there are 2 thread groups under the same test plan then ${__threadNum} will return the values for each thread like below:
| Thread Group | Number of Threads | Return Value |
|---|---|---|
| Thread Group 01 | 2 | ${__threadGroup} = 1 // called by thread 1 ${__threadGroup} = 2 // called by thread 2 |
| Thread Group 02 | 4 | ${__threadGroup} = 1 // called by thread 1 ${__threadGroup} = 2 // called by thread 2 ${__threadGroup} = 3 // called by thread 3 ${__threadGroup} = 4 // called by thread 4 |
Input Argument: No input value can pass in the threadNum() function.
Return Value: A natural number i.e. 1 to the maximum thread run under a thread group. The number belongs to the individual thread.
Use: The threadNum function has a specific use. If you want to get the response time of a transaction/request for each thread then you can pass the thread number in the name of the transaction/request.
Limitation:
- The threadNum() does not work in any Configuration elements (e.g. User Defined Variables) as these are run from a separate thread.
- It works only under the Thread Group level; not at the Test Plan level.
Related Functions:
- getThreadNum(): It returns a number between zero and (max number of running threads minus one). You can use this function as below under the JSR223 post-processor.
- Note: ctx is a variable to call JMeterContextClass.
log.info("Thread Number is: "+ctx.getThreadNum());You may be interested: