Re: [Caml-list] BUG in unix.ml (was: strange errors when linking lwt.unix)

[Jeremie Dimino <jdimino@janestreet.com>]

On Fri, Mar 15, 2013 at 9:18 AM, Florian Hars <florian@hars.de> wrote:
> It probably escaped notice so far because only lwt_unix does enough strange
> things with signals in the default config to trigger it reliably.

Indeed.  BTW the only "strange" thing lwt does by default with signals
is to set a handler for SIGCHLD.

Actually here is a way to reproduce this behavior without lwt on OSX
and some other systems:

    # #load "unix.cma";;
    # Sys.set_signal Sys.sigchld (Sys.Signal_handle ignore);;
    - : unit = ()
    # Unix.system "true";;
    Exception: Unix.Unix_error (Unix.EINTR, "waitpid", "").

This will happen in any program setting a handler for SIGCHLD.

To avoid this you can:

- if you are using lwt, use Lwt_unix.system
- block SIGCHLD in the current thread while calling Unix.system
- write your own system function

Maybe this should be the default behavior.  Can you open a ticket on
mantis about this?

Cheers,
Jeremie