Problem: The concurrent.futures ThreadPoolExecutor is not explicitly shut down when exiting flux-job-validator. This MAY be causing the program to occasionally hang at exit.
Add a stop() method to the JobValidator class which calls the shutdown() method of the executor. Call validator.stop() from flux-job-validator(1) before exit.
Problem: The concurrent.futures ThreadPoolExecutor is not explicitly shut down when exiting flux-job-validator. This MAY be causing the program to occasionally hang at exit.
Add a stop() method to the JobValidator class which calls the shutdown() method of the executor. Call validator.stop() from flux-job-validator(1) before exit.
Fixes #6434