Changes/Python 3.4

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(Finish the rough proposal, to be reviewed before submitting)
(Improvements, more specific schedule)
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== Current status ==
 
== Current status ==
 
* Targeted release: [[Releases/21 | Fedora 21 ]]  
 
* Targeted release: [[Releases/21 | Fedora 21 ]]  
* Last updated: August 26
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* Last updated: August 26, 2013
 
<!-- After the change proposal is accepted by FESCo, tracking bug is created in Bugzilla and linked to this page  
 
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Compare with the [[Features/Python_3.3| Python 3.3 feature page]].
 
Compare with the [[Features/Python_3.3| Python 3.3 feature page]].
  
We need to wait for Python 3.4 to reach feature freeze, so that the bytecode format for .pyc files is frozen, together with the ABI for extension modules.
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We need to wait for Python 3.4 to reach feature freeze (planned for 3.4.0 beta 1: November 24, 2013), so that the bytecode format for .pyc files is frozen, together with the ABI for extension modules.
  
 
At that point we can rebase python3 to the latest release candidate of that code.  We would then need to rebuild all python 3 packages.  See https://fedoraproject.org/wiki/Python3#Python_3_already_in_Fedora
 
At that point we can rebase python3 to the latest release candidate of that code.  We would then need to rebuild all python 3 packages.  See https://fedoraproject.org/wiki/Python3#Python_3_already_in_Fedora
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* Proposal owners:
 
* Proposal owners:
This change is isolated to Python 3 stack, which is not yet crucial for Fedora. Still, as the time of moving Fedora to Python 3 is hopefully approaching, we need to do this very cautiously. I will prepare Python 3.4 prerelease RPMs in a private repo and will do a test rebuild of all Python 3 dependent packages, filing bugs/sending patches to upstreams. This will give us a good notion of how drastic this change will be and whether or not we really want to undergo it. Overall, the change will consist of these steps:
+
This change is isolated to Python 3 stack, which is not yet crucial for Fedora. Still, as the time of moving Fedora to Python 3 is hopefully approaching, we need to do this very cautiously. I will prepare Python 3.4 prerelease RPMs in a private repo and will do a test rebuild of all Python 3 dependent packages, filing bugs/sending patches to upstreams. This will give us a good notion of how drastic this change will be and whether or not we really want to undergo it. Overall, the change should have roughly this schedule:
** Build Python 3.4 prerelease in a private repo, continuously upgrading with latest upstream prerelease versions.
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# After change is accepted: Start building Python 3.4 prereleases in a private repo, continuously upgrading with latest upstream prerelease versions.
** Build Python 3 dependent packages in the repo continuously.
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# November 24, 2013 (3.4.0 beta 1: feature freeze): Start rebuilding Python 3 dependent packages in the repo.
** Some time before final release (e.g. around 3.4.0 candidate 1: January 19, 2014) request a side tag in Koji and start rebuilding there.
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# January 19, 2014 (3.4.0 candidate 1) Request a side tag in Koji and start rebuilding there.
** If everything goes well, merge into F21.
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# February 23, 2014 (3.4.0 final) If everything goes went well up to this point, merge into F21.
 
<!-- What work do the feature owners have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
 
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== Contingency Plan ==
 
== Contingency Plan ==
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As mentioned in "Scope" above, we will be building everything in Koji sidetag, so we may decide not to merge it in F21, if anything seems to be wrong.
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<!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration".  Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
 
<!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration".  Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
* Contingency mechanism: (What to do?  Who will do it?) N/A (not a System Wide Change)  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
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* Contingency mechanism: Don't merge Koji sidetag into F21.
 
<!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
 
<!-- When is the last time the contingency mechanism can be put in place?  This will typically be the beta freeze. -->
* Contingency deadline: N/A (not a System Wide Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
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* Contingency deadline: TBD (probably F21 beta change deadline)
 
<!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
 
<!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
* Blocks release? N/A (not a System Wide Change), Yes/No <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
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* Blocks release?: We will merge to F21 only under the condition that reasonably small amount of packages doesn't build/work with Python 3.4. (will be decided before merge)
  
 
== Documentation ==
 
== Documentation ==
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As mentioned in "Scope" above, we will be building everything in Koji sidetag, so we may decide not to merge it in F21, if anything seems to be wrong.
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http://www.python.org/dev/peps/pep-0429/
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http://docs.python.org/dev/whatsnew/3.4.html
  
 
== Release Notes ==
 
== Release Notes ==

Revision as of 08:04, 26 August 2013


Contents

Python 3.4

Summary

Update the Python 3 stack in Fedora from Python 3.3 to Python 3.4.

Owner

  • Name: Slavek Kabrda
  • Email: <bkabrda@redhat.com>
  • Release notes owner:

Current status

  • Targeted release: Fedora 21
  • Last updated: August 26, 2013
  • Tracker bug: <will be assigned by the Wrangler>

Detailed Description

Python 3.4 adds numerous features and optimizations. See the upstream notes at http://www.python.org/dev/peps/pep-0429/#features-for-3-4 and http://docs.python.org/dev/whatsnew/3.4.html.

Benefit to Fedora

Fedora aims to showcase the latest in free and open source software - we should have the most recent release of Python 3.

Scope

Compare with the Python 3.3 feature page.

We need to wait for Python 3.4 to reach feature freeze (planned for 3.4.0 beta 1: November 24, 2013), so that the bytecode format for .pyc files is frozen, together with the ABI for extension modules.

At that point we can rebase python3 to the latest release candidate of that code. We would then need to rebuild all python 3 packages. See https://fedoraproject.org/wiki/Python3#Python_3_already_in_Fedora

For bonus points, we ought to tell "file" and "rpmlint" about the new bytecode format for .pyc files.

Note that the suffix of some files should change, and this may require slight packaging tweaks in the various packages that ship Python 3 code:

  • bytecode files changing from .cpython-33.pyc (and .cpython-33.pyo) to .cpython-34.pyc (and .cpython-34.pyo)
  • extension modules changing from .cpython-33m.so to .cpython-34m.so and .cpython-33dm.so to .cpython-34dm.so

Notes about porting from Python 3.3 can be found at http://docs.python.org/dev/whatsnew/3.4.html#porting-to-python-3-4.


  • Proposal owners:

This change is isolated to Python 3 stack, which is not yet crucial for Fedora. Still, as the time of moving Fedora to Python 3 is hopefully approaching, we need to do this very cautiously. I will prepare Python 3.4 prerelease RPMs in a private repo and will do a test rebuild of all Python 3 dependent packages, filing bugs/sending patches to upstreams. This will give us a good notion of how drastic this change will be and whether or not we really want to undergo it. Overall, the change should have roughly this schedule:

  1. After change is accepted: Start building Python 3.4 prereleases in a private repo, continuously upgrading with latest upstream prerelease versions.
  2. November 24, 2013 (3.4.0 beta 1: feature freeze): Start rebuilding Python 3 dependent packages in the repo.
  3. January 19, 2014 (3.4.0 candidate 1) Request a side tag in Koji and start rebuilding there.
  4. February 23, 2014 (3.4.0 final) If everything goes went well up to this point, merge into F21.
  • Other developers:

I'll gladly accept any help with rebuilding/porting/patching/bug reporting of dependent packages as well as suggestions for Python 3.4 packaging itself. When we're sure that we really want to do the transition, it'd be great if package owners rebuild their packages themselves.

  • Release engineering:

We will most likely require a side tag in Koji for this.

  • Policies and guidelines:

Probably none.

Upgrade/compatibility impact

User written Python 3 scripts/applications may require a small amount of porting, but mostly Python 3.3 is forward compatible with Python 3.4.

How To Test

Interested testers do not need special hardware. If you have a favorite Python 3 script, module, or application, please test it with Python 3.4 and verify that it still works as you expect.

My own test plan:

  • Smoketest of the interpreter
  • Run the upstream regression test suite (this is done during %check)

User Experience

Users should not notice any difference, other than the availability of the 3.4 interpreter

Dependencies

See notes in "Scope" above.

Contingency Plan

As mentioned in "Scope" above, we will be building everything in Koji sidetag, so we may decide not to merge it in F21, if anything seems to be wrong.

  • Contingency mechanism: Don't merge Koji sidetag into F21.
  • Contingency deadline: TBD (probably F21 beta change deadline)
  • Blocks release?: We will merge to F21 only under the condition that reasonably small amount of packages doesn't build/work with Python 3.4. (will be decided before merge)

Documentation

http://www.python.org/dev/peps/pep-0429/ http://docs.python.org/dev/whatsnew/3.4.html

Release Notes

http://docs.python.org/dev/whatsnew/3.4.html