[Bug 242274] lang/python??: adopt local closefrom(2) patches

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242274

--- Comment #4 from commit-hook at freebsd.org ---
A commit references this bug:

Author: koobs
Date: Fri Nov 29 10:55:03 UTC 2019
New revision: 518640
URL: https://svnweb.freebsd.org/changeset/ports/518640

Log:
  lang/python{27,35,36,37,38}: Add closefrom(2) support

  A single close(fd) syscall is cheap, but when MAXFDS (maximum file
  descriptor number) is high, the loop calling close(fd) on each file
  descriptor can take several milliseconds.

  The default value of subprocess.Popen "close_fds" parameter changed to True
  in Python 3. Compared to Python 2, close_fds=True can make Popen 10x
  slower: see bpo-37790 [1]

  The present workaround on FreeBSD to improve performance is to load and
  mount the fdescfs kernel module, but this is not enabled by default.

  This change adds minimum viable (and upstreamable) closefrom(2) syscall
  support to Python's subprocess and posix modules, improving performance
  significantly for loads that involve working with many processes, such as
  diffoscope, ansible, and many others.

  For additional optimizations, upstream recently (3.8) landed posix_spawn(2)
  support [3] and has stated that they will adopt close_range(2) after Linux
  merges it [4]. Linux/FreeBSD developers are already collaborating on
  ensuring compatible implementations, with FreeBSD's implementation pending
  in D21627. [5]

  Thank you emaste, cem, kevans for providing analysis, input,
  clarifications, comms/upstream support and patches.

  [1] https://bugs.python.org/issue37790
  [2] https://bugs.python.org/issue38061
  [3] https://bugs.python.org/issue35537
  [4] https://lwn.net/Articles/789023/
  [5] https://reviews.freebsd.org/D21627

  Additional References:

  https://bugs.python.org/issue8052
  https://bugs.python.org/issue11284
  https://bugs.python.org/issue13788
  https://bugs.python.org/issue1663329
  https://www.python.org/dev/peps/pep-0446/

  PR:           242274, 221700
  Submitted by: kevans (emaste, cem)
  Approved by:  koobs (python (maintainer), santa)

Changes:
  head/lang/python27/Makefile
  head/lang/python27/files/patch-Modules_posixmodule.c
  head/lang/python35/Makefile
  head/lang/python35/files/patch-Modules___posixsubprocess.c
  head/lang/python35/files/patch-Modules_posixmodule.c
  head/lang/python36/Makefile
  head/lang/python36/files/patch-Modules___posixsubprocess.c
  head/lang/python36/files/patch-Modules_posixmodule.c
  head/lang/python37/Makefile
  head/lang/python37/files/patch-Modules___posixsubprocess.c
  head/lang/python37/files/patch-Modules_posixmodule.c
  head/lang/python38/Makefile
  head/lang/python38/files/patch-Modules___posixsubprocess.c
  head/lang/python38/files/patch-Modules_posixmodule.c

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