Question: Is it recommed to put a while loop, which never ends in a constructor? Or should I use threads to get the same result?
Is it good when a constructor never terminates? Or is it more secure to avoid segmentation faults?

Hope you understand my bad English..

Answer: 
An object does not exist if its constructor does not finish. So putting a while(1) loop in a constructor will prevent objects being created using that constructor. You need to describe what problem you think doing this will solve.
Your code shouldn't generate a segmentation fault whether or not it uses multiple threads or contains infinite loops.

None of those have anything to do with segmentation faults. If those occur, you need to fix that problem