Implement multiprocessing without inheriting parent file handle

Chris Angelico rosuav at
Fri Mar 21 23:50:07 CET 2014

On Sat, Mar 22, 2014 at 5:16 AM, Mark H Harris <harrismh777 at> wrote:
> On 3/21/14 12:42 PM, Marko Rauhamaa wrote:
>> It's got the optional close_fds parameter, which is True by default.
>> IOW, you don't need to do anything if you use subprocess.Popen() to
>> start your child process. Incidentally, that's the preferred way.
> hi Marko, of course this depends on the environment; if unix-like, then yes,
> elif windows well, not so much...
> There are caveats about stdin, stdout, and stderr;  as well, there are
> caveats about passing fds between the two. Well, Popen() is implemented on
> unix and windows differently, so there is some study needed here if code is
> going to be run in both environments.

There were some recent changes, though, including making CLOEXEC the
default, which means that fork/exec on Unix will retain only the fds
you actually want.


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