UTop blocks and has to be kill'd -9 after a forked child terminates

[Armael]

Not sure this title is the most accurate description of the problem, but after running the following piece of code:

match Unix.fork () with
| 0 -> print_endline "hello"; exit 0
| pid -> Unix.waitpid [] pid

utop blocks; then if I try to hit Control-C, utop completely freezes and I have to kill it by sending SIGKILL (kill -9).

[Armael]

Any news?

[ghost]

I had a look; this is linked to lwt and some at_exit handler. Currently there are two ways to solve the problem:

• replace Unix.fork by Lwt_unix.fork

• replace exit by this external which doesn't run exit handlers:

  external sys_exit : int -> unit = "caml_sys_exit"
  

Unfortunately I don't have a better solution for now. At some point I'm planning to stop using lwt in lambda-term, so that one is free to use lwt, async or something else. That will solve these problems but I haven't had the time to work on this yet