[tahoe-lafs-trac-stream] [tahoe-lafs] #1658: drop support for Python < 2.6

[tahoe-lafs]

#1658: drop support for Python < 2.6
---------------------------+----------------------------------------------
     Reporter:  zooko      |      Owner:  somebody
         Type:  defect     |     Status:  new
     Priority:  major      |  Milestone:  1.10.0
    Component:  packaging  |    Version:  1.9.0
   Resolution:             |   Keywords:  packaging backward-compatibility
Launchpad Bug:             |
---------------------------+----------------------------------------------

Old description:

> Let's drop support for versions of Python < 2.6. According to
> distrowatch's tables about the versions of packages that come with
> distros, this would exclude Tahoe-LAFS 1.10 from being usable with the
> included Python on the following versions of major distros:
>
> ||= distro =||= excluded version =||= excluded version release date =||=
> oldest supported version of the operating system =||= oldest supported
> release date =||= Python in oldest supported =||= notes =||= next version
> =||= Python in next version =||
> ||=[http://distrowatch.com/table.php?distribution=fedora Fedora]   =||=10
> =||=2008-11-25 =||=15        =||=2011-05-24 =||=2.7 =||= =||=rawhide will
> be 17 =||=2.7.2 =||
> || [http://distrowatch.com/table.php?distribution=ubuntu Ubuntu]    ||
> 8.10 || 2008-10-30  || 10.04 LTS  || 2010-04-29  || 2.6  || || will be
> 12.04 precise ||2.7.2 ||
> ||=[http://distrowatch.com/table.php?distribution=debian Debian]
> =||=5.0 =||=2009-02-15 =||=6.0       =||=2011-02-06 =||=2.6 =||=
> =||=unstable sid will be 7.0 =||=2.7.2 =||
> || [http://distrowatch.com/table.php?distribution=freebsd FreeBSD]  ||
> 7.2  || 2009-05-04  || 7.1        || 2009-01-05  || 2.5  || but upgrading
> is supposed to be pretty safe within the same major series (7.x) and 7.3
> (2010-03-23) has Python 2.6  ||10 CURRENT ||2.7.2 ||
> ||=[http://distrowatch.com/table.php?distribution=redhat RedHat]
> =||=5.7 =||=2011-07-21 =||=5.7       =||=2011-07-21 =||=2.4 =||= I'm told
> that people tend to install their own newer version of Python when they
> want to use newer Python programs on older RHEL  =||=(current, not next)
> 6.2 =||=2.6.6 =||
>
> Among other benefits, dropping support for Pythons older than 2.6 would
> allow us to remove the
> [source:git/src/allmydata/_auto_deps.py?annotate=blame&rev=76e7f0ad4b0d109a9a92e451ac9b3c9e8a827eb0#L15
> dependency on simplejson] and the (complex imperatively decided)
> [source:git/src/allmydata/_auto_deps.py?annotate=blame&rev=76e7f0ad4b0d109a9a92e451ac9b3c9e8a827eb0#L92
> dependency on pysqlite].

New description:

 Let's drop support for versions of Python < 2.6. According to
 distrowatch's tables about the versions of packages that come with
 distros, this would exclude Tahoe-LAFS 1.10 from being usable with the
 included Python on the following versions of major distros:

 ||= distro =||= excluded version =||= excluded version release date =||=
 oldest supported[*] version =||= oldest supported[*] release date =||=
 Python in oldest supported[*] =||= notes =||= next version =||= Python in
 next version =||
 ||=[http://distrowatch.com/table.php?distribution=fedora Fedora]   =||=10
 =||=2008-11-25 =||=15        =||=2011-05-24 =||=2.7 =||= =||=rawhide will
 be 17 =||=2.7.2 =||
 || [http://distrowatch.com/table.php?distribution=ubuntu Ubuntu]    ||
 8.10 || 2008-10-30  || 10.04 LTS  || 2010-04-29  || 2.6  || || will be
 12.04 precise ||2.7.2 ||
 ||=[http://distrowatch.com/table.php?distribution=debian Debian]   =||=5.0
 =||=2009-02-15 =||=6.0       =||=2011-02-06 =||=2.6 =||= =||=unstable sid
 will be 7.0 =||=2.7.2 =||
 || [http://distrowatch.com/table.php?distribution=freebsd FreeBSD]  || 7.2
 || 2009-05-04  || 7.1        || 2009-01-05  || 2.5  || but upgrading is
 supposed to be pretty safe within the same major series (7.x) and 7.3
 (2010-03-23) has Python 2.6  ||10 CURRENT ||2.7.2 ||
 ||=[http://distrowatch.com/table.php?distribution=redhat RedHat]   =||=5.7
 =||=2011-07-21 =||=5.7       =||=2011-07-21 =||=2.4 =||= I'm told that
 people tend to install their own newer version of Python when they want to
 use newer Python programs on older RHEL  =||=(current, not next) 6.2
 =||=2.6.6 =||

 Among other benefits, dropping support for Pythons older than 2.6 would
 allow us to remove the
 [source:git/src/allmydata/_auto_deps.py?annotate=blame&rev=76e7f0ad4b0d109a9a92e451ac9b3c9e8a827eb0#L15
 dependency on simplejson] and the (complex imperatively decided)
 [source:git/src/allmydata/_auto_deps.py?annotate=blame&rev=76e7f0ad4b0d109a9a92e451ac9b3c9e8a827eb0#L92
 dependency on pysqlite].

 [*] that is, the oldest OS version supported by the OS distributors and
 still receiving security patches.

--

Comment (by davidsarah):

 sqlite bindings are in Python 2.5, and so is `hashlib.sha256`. When we've
 had buildslave failures for unsupported syntax, they've usually been for
 2.4.x and not 2.5. So is the `simplejson` dependency the only reason to
 drop support for 2.5?

 If so, note that the `json` module in the stdlib is ''not'' identical to
 `simplejson`. According to [http://stackoverflow.com/questions/712791
 /json-and-simplejson-module-differences-in-python], the stdlib version is
 less frequently updated and slower (although I would be more concerned
 about security-relevant bugfixes than speed).

 I agree we should definitely drop support for 2.4.x.

 zooko wrote:
 > "oldest supported version of the operating system" is supposed to be the
 oldest release of the operating system that is supported *by the operating
 system distributors*, i.e. the oldest release of the operating system that
 still gets security patches.

 Oh, ok, that wasn't at all obvious.

-- 
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1658#comment:10>
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