[Distutils] entry points PEP

[Joe Gordon]

I have gone ahead and gathered some information using our standard
development environment, devstack, I ran cProfile on our application, with
the contents of it mocked out,

http://paste.openstack.org/show/40948/


When I try importing pkg_resources in our development environment it is
very slow:


vagrant at precise64:/opt/stack/nova$ time python -c "from pkg_resources
import load_entry_point"

real    0m0.185s
user    0m0.136s
sys     0m0.044s


vagrant at precise64:/opt/stack/nova$ time python -c "print 'hi'"
hi

real    0m0.047s
user    0m0.036s
sys     0m0.008s



I also ran cProfile on just the import line:


http://paste.openstack.org/show/40949/



and

$ python -vvvvvv -c "import pkg_resources"


http://paste.openstack.org/show/40952/



As for python 3, we have to maintain python 2.6  and 2.7 compatibility
so a Python 3 only fix isn't acceptable



On Fri, Jul 19, 2013 at 5:58 AM, Daniel Holth <dholth at gmail.com> wrote:

> On Fri, Jul 19, 2013 at 5:32 AM, Robert Collins
> <robertc at robertcollins.net> wrote:
> > On 19 July 2013 21:24, Vinay Sajip <vinay_sajip at yahoo.co.uk> wrote:
> >> Robert Collins <robertc <at> robertcollins.net> writes:
> >>
> >>> So my question here would be - can we make it faster? We have just
> >>> been diagnosing a performance problem in nova due to rootwrap being a
> >>> pkg_resources scripts entry point : just getting to the first line of
> >>> main() takes 200ms, and we make dozens of subprocess calls (has to be,
> >>> we're escalating privileges) to the script in question : that time is
> >>> nearly entirely doing introspection of metadata from disk.
> >>
> >> Is there more detailed information about where the time is being spent?
> e.g.
> >> os.stat(), file I/O, parsing of the actual metadata files,
> load_entry_point()
> >> etc.
> >
> > Not sure. Joe?
> >
> > -Rob
>
> You should at least time it against the simpler "import sys, x.main;
> sys.exit(main())" style wrapper.
>
> As a pkg_resources optimization it might be worthwhile to try using
> https://github.com/benhoyt/scandir/ or in Python 3, the undocumented
> cache used by the importer system, to try to speed things up.
>
> It is a bit tricky to profile pkg_resources since it does a lot of
> work at import.
>
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