[Bug 1638695] Re: Python 2.7.12 performance regression

[Łukasz Zemczak]

Hello Major, or anyone else affected,

Accepted python2.7 into zesty-proposed. The package will build now and
be available at
https://launchpad.net/ubuntu/+source/python2.7/2.7.13-2ubuntu0.2 in a
few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-zesty to verification-done-zesty. If it does not fix
the bug for you, please add a comment stating that, and change the tag
to verification-failed-zesty. In either case, details of your testing
will help us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Changed in: python2.7 (Ubuntu Zesty)
       Status: New => Fix Committed

** Tags added: verification-needed verification-needed-zesty

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https://bugs.launchpad.net/bugs/1638695

Title:
  Python 2.7.12 performance regression

Status in python2.7 package in Ubuntu:
  Fix Released
Status in python2.7 source package in Xenial:
  Confirmed
Status in python2.7 source package in Zesty:
  Fix Committed

Bug description:
  SRU: Looks like only the math.o build without -fPIC makes it into the
  SRU. There shouldn't be any regression potential when building without
  -fPIC for the static interpreter.  Acceptance criteria is running the
  benchmarks and not showing any performance regressions.

  I work on the OpenStack-Ansible project and we've noticed that testing
  jobs on 16.04 take quite a bit longer to complete than on 14.04.  They
  complete within an hour on 14.04 but they normally take 90 minutes or
  more on 16.04.  We use the same version of Ansible with both versions
  of Ubuntu.

  After more digging, I tested python performance (using the
  'performance' module) on 14.04 (2.7.6) and on 16.04 (2.7.12).  There
  is a significant performance difference between each version of
  python.  That is detailed in a spreadsheet[0].

  I began using perf to dig into the differences when running the python
  performance module and when using Ansible playbooks.  CPU migrations
  (as measured by perf) are doubled in Ubuntu 16.04 when running the
  same python workloads.

  I tried changing some of the kerne.sched sysctl configurables but they
  had very little effect on the results.

  I compiled python 2.7.12 from source on 14.04 and found the
  performance to be unchanged there.  I'm not entirely sure where the
  problem might be now.

  We also have a bug open in OpenStack-Ansible[1] that provides
  additional detail. Thanks in advance for any help you can provide!

  [0] https://docs.google.com/spreadsheets/d/18MmptS_DAd1YP3OhHWQqLYVA9spC3xLt4PS3STI6tds/edit?usp=sharing
  [1] https://bugs.launchpad.net/openstack-ansible/+bug/1637494

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