On Jun 4, 2019, at 08:11, STINNER Victor <report@bugs.python.org> wrote:
> Ned Deily:
>> No, it has *always* been unsafe. What's new as of 10.13/14 is that macOS tries much harder at runtime to detect such cases and more predictably cause an error rather than letter than let the process run on and possibly fail nondeterministically.
> 
> Hum, in the doc, I wrote:
> 
> .. versionchanged:: 3.8
> 
>   On macOS, *spawn* start method is now the default: *fork* start method is no
>   longer reliable on macOS, see :issue:`33725`.
> 
> Should we change this text? Any proposition?

Thanks Victor.  I don’t think “reliable” is strong enough, since this will definitely lead to core dumps under certain conditions.  What about:

   On macOS, the *spawn* start method is now the default.  The *fork* start method should
   be considered unsafe as it can lead to crashes of the subprocess.  See :issue:`33725`.