python-peps/pep-0006.txt

PEP: 6
Title: Bug Fix Releases
Version: $Revision$
Author: aahz@pobox.com (Aahz)
Status: Draft
Type: Informational
Created: 15-Mar-2001
Post-History: 15-Mar-2001


Abstract

    Python has historically had only a single fork of development,
    with releases having the combined purpose of adding new features
    and delivering bug fixes (these kinds of releases will be referred
    to as "feature releases").  This PEP describes how to fork off
    patch releases of old versions for the primary purpose of fixing
    bugs.

    This PEP is not, repeat NOT, a guarantee of the existence of patch
    releases; it only specifies a procedure to be followed if patch
    releases are desired by enough of the Python community willing to
    do the work.


Motivation

    With the move to SourceForge, Python development has accelerated.
    There is a sentiment among part of the community that there was
    too much acceleration, and many people are uncomfortable with
    upgrading to new versions to get bug fixes when so many features
    have been added, sometimes late in the development cycle.

    One solution for this issue is to maintain the previous feature
    release, providing bug fixes until the next feature release.  This
    should make Python more attractive for enterprise development,
    where Python may need to be installed on hundreds or thousands of
    machines.


Prohibitions

    Patch releases are required to adhere to the following restrictions:

    1. There must be zero syntax changes.  All .pyc and .pyo files
       must work (no regeneration needed) with all patch releases
       forked off from a feature release.

    2. There must be zero pickle changes.

    3. There must be no incompatible C API changes.  All extensions
       must continue to work without recompiling in all patch releases
       in the same fork as a feature release.

    Breaking any of these prohibitions requires a BDFL proclamation
    (and a prominent warning in the release notes).


Version Numbers

    Starting with Python 2.0, all feature releases are required to
    have a version number the form X.Y; patch releases will always be
    of the form X.Y.Z.

    The current feature release under development is referred to as
    release N; the just-released feature version is referred to as
    N-1.


Procedure

    The process for managing patch releases is modeled in part on the
    Tcl system [1].

    The Patch Czar is the counterpart to the BDFL for patch releases.
    However, the BDFL and designated appointees retain veto power over
    individual patches.

    As individual patches get contributed to the feature release fork,
    each patch contributor is requested to consider whether the patch is
    a bug fix suitable for inclusion in a patch release.  If the patch is
    considered suitable, the patch contributor will mail the SourceForge
    patch (bug fix?) number to the maintainers' mailing list.

    In addition, anyone from the Python community is free to suggest
    patches for inclusion.  Patches may be submitted specifically for
    patch releases; they should follow the guidelines in PEP 3 [2].

    The Patch Czar decides when there are a sufficient number of
    patches to warrant a release.  The release gets packaged up,
    including a Windows installer, and made public.  If any new bugs
    are found, they must be fixed immediately and a new patch release
    publicized (with an incremented version number).

    Patch releases are expected to occur at an interval of roughly one
    month.  In general, only the N-1 release will be under active
    maintenance at any time.


Patch Czar History

    Moshe Zadka (moshez@zadka.site.co.il) is the Patch Czar for 2.0.1.


Issues To Be Resolved

    What is the equivalent of python-dev for people who are
    responsible for maintaining Python?  (Aahz proposes either
    python-patch or python-maint, hosted at either python.org or
    xs4all.net.)

    Does SourceForge make it possible to maintain both separate and
    combined bug lists for multiple forks?  If not, how do we mark
    bugs fixed in different forks?  (Simplest is to simply generate a
    new bug for each fork that it gets fixed in, referring back to the
    main bug number for details.)


History

    This PEP started life as a proposal on comp.lang.python.  The
    original version suggested a single patch for the N-1 release to
    be released concurrently with the N release.  The original version
    also argued for sticking with a strict bug fix policy.

    Following feedback from the BDFL and others, the draft PEP was
    written containing an expanded patch release cycle that permitted
    any previous feature release to obtain patches and also relaxed
    the strict bug fix requirement (mainly due to the example of PEP
    235 [3], which could be argued as either a bug fix or a feature).

    Discussion then mostly moved to python-dev, where BDFL finally
    issued a proclamation basing the Python patch release process on
    Tcl's, which essentially returned to the original proposal in
    terms of being only the N-1 release and only bug fixes, but
    allowing multiple patch releases until release N is published.


References

    [1] http://dev.scriptics.com:8080/cgi-bin/tct/tip/28.html

    [2] http://python.sourceforge.net/peps/pep-0003.html

    [3] http://python.sourceforge.net/peps/pep-0235.html


Copyright

    This document has been placed in the public domain.



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