If the threads/processes are simply doing tests and not writing to anything, such that they will not leave anything in an inconsistent state, then you can simply terminate the parent process and the children will necessarily die. C'est la guerre. No permanent harm will be caused. Ignore the message.
Comment on Re: How to simply terminate all running threads?
Sunny, do shut up. You're pathetic attempts to disguise your posts are useless when you use one of your signature phrases like "C'est la guerre". Even when you omit your usual graphstrionics.
Especially when, as normal, you use it in a totally inappropriate context.