junit - Java Unit Tests - Parallelization + Multiple Threads + Infinite times

I have bunch of Java JUnit test classes that make REST calls to Elastic Search. I am trying to check what is the best way to orchestrate the test suite so it satisfies the following -

1. Run them infinitely with different input parameters [helps me to load test ElasticSearch and gather response time(s) and check on caching features of ES etc]


2. Run several of these test classes in parallel


3. Run them in a multi-threaded fashion

Note # I understand there are several different ways to achieve it, for example using JMeter etc. I am trying to see if this can be achieved programatically.

One idea is to create a test suite in TestNG with parallelism option enabled and setting a cron to invoke the Test suite every X number of minutes.[how can I change the thread count here?]

Thanks!