IMO it's fine to be scared of these, and fine to be scared of threads (and I have similar feelings about floating-point). You don't actually need threads; threads can't do anything that processes can't, indeed in the Linux 2.4 days threads and processes were the same thing to the scheduler. The fact that there are programs in common use that handle signals does not convince me that it's possible to handle signals correctly in all cases; lots of programs get used for decades while being subtly broken (see the famous "you are not expected to understand this").