> We've moved illumos-gate wsdiff python tool from Python 2 to Python 3.

I guess that you're talking about https://github.com/illumos/illumos-gate/blob/master/usr/src/tools/scripts/wsdiff.py

This project is part of illumos: "An open-source Unix operating system". It's a fork of Solaris.

Python does not officially support Solaris not Illumos. If someone provides a patch, we can review it. But I'm not aware of anyone working actively on supporting Illumos.

In the meanwhile, there are two workarounds:

* Use subprocess.Popen(close_fds=False): it should be safe since PEP 446 has been implemented in Python 3.4... except for C extension modules and C libraries which don't implement it.
* Reduce the maximum number of file descriptors.

On Linux and FreeBSD (if fdescfs kernel module is loaded and mounted), Python 3 iterates on /proc/self/fd/. On FreeBSD, the closefrom() syscall can be used: PR 19697. But I'm not aware of any more efficient solution for Illumos.

Since the latest comment of the original poster was last August, I close the issue.