beanshell property not updated in subsequent iteration of While Controller - properties

Question

I have a JMeter test which should execute a fixed number of REST calls executed by a configurable number of users concurrently. So depending on the responsetime of the REST call, one user may have executed a slightly more number of REST calls than an other user.
To do this i have created a Beanshell PreProcessor with a script. This script copies the value from a user defined variable maxdocumentuploads to the property documentuploads.
props.put("documentuploads",${maxdocumentuploads})
log.info(">>>INIT> " + props.get("documentuploads"));
In a Thread Group a While Controller is created with condition ${__groovy(props.get("documentuploads") > 0 )}. The first child of the While Controller is a BeanShell PreProcessor with a script that reads the property, decrements the value of the property and puts the decremented value.
log.info(">>>GET> " + props.get("documentuploads"));
int counter = props.get("documentuploads") ;
counter--;
log.info(">>>INC> " + counter);
props.put("documentuploads", counter);
log.info(">>>CHK> " + props.get("documentuploads"));
Simplified the Testplan is setup like this;
Test Plan
+ init counter (Beanshell PreProcessor)
+ Users (Thread Group)
+ While Contoller
+ BeanShell PreProcessor
The log.info shows that the property is updated with the new value, but on each iteration the value of the property is back to the initial value.
The BeanShell PreProcessor 'init counter' is executed on each iteration of the While Controller. How can i initialize a property on start of a test plan with the value of a test plan User Defined Variable without having it re-set each iteration of the while controller.

Answer 1

Add parent for preprocessor so it will execute once before parent
Put as parent Flow Control Action with Duration, which will do nothing except executing the beanshell script
Consider changing beanshell to JSR223 script
Another option is to add as parent an If Controller and check while controller's counter
Another option is to use Sampler instead of PreProcessor so it will executed once.