[Bug 1627190] Re: livecd-rootfs: .pyc files stripped from desktop ISO livefs, makes python startup slower

[Steve Langasek]

On Fri, Sep 30, 2016 at 01:22:22PM -0000, Iain Lane wrote:
> > > Should we make this call for flavours too?

> > They should have the option, and we shouldn't make such a change during
> > release freeze.  But I think the evidence is strong that we should reverse
> > the default.

> I don't really understand this bit. Are you saying that we should *not*
> change this for Yakkety for Ubuntu Desktop?

> What I propose to do (now or next cycle, as decided) is make .pyc
> stripping opt-in.

> If this cycle, then opt every flavour except Ubuntu Desktop and the ones
> already excluded in and mail announcing the change to give flavours a
> chance to switch too.

> At the start of next cycle, opt every flavour out and give the chance to
> opt opt back in. If there are no takers, then we can delete the code
> altogether.

Ok.  I'm comfortable with the desktop team making this decision for their
own images post-beta.  I just don't want us to be making a change that
impacts any other flavors post-beta without their buy-in.

So if we do it now, the process is:

 - invert the logic
 - compile a complete list of all flavors building livefses and add them to
   the opt-in list
 - send mail to ubuntu-release or something encouraging flavors to drop
   themselves from the opt-in list if they're comfortable with the change
 - wait forever for everybody to do this

If we wait until the opening of the cycle, the process can be:

 - invert the logic
 - add support for opt-in list but leave it empty by default
 - send mail to ubuntu-release letting flavors know about the change,
   encouraging them to leave everything as-is unless they have specific size
   problems

The latter seems preferable to me, but means we have to leave this bug open
for 2 more weeks :)

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https://bugs.launchpad.net/bugs/1627190

Title:
  livecd-rootfs: .pyc files stripped from desktop ISO livefs, makes
  python startup slower

Status in livecd-rootfs package in Ubuntu:
  New

Bug description:
  It seems we've had code in livecd-rootfs for roughly forever to strip
  .pyc files out of the squashfs included on desktop images.  There is
  an override to skip this for server and cloud images, but we
  discovered this recently because the missing .pyc files on ubuntu-core
  images causes very long start-up times for python apps on some armhf
  systems.

  So the question is, is this still a sensible optimization on Ubuntu
  Desktop images?  It was done at a time when space was tight; that's
  much less of a concern now than it was.

  If this does still make sense for Desktop, we should probably at least
  invert the logic to make this opt-in rather than opt-out so that new
  image types on ARM don't get caught out with the problem.

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