[Python-Dev] More optimisation ideas

[Brett Cannon]

On Sat, 30 Jan 2016 at 10:21 Serhiy Storchaka <storchaka at gmail.com> wrote:

> On 30.01.16 18:31, Steve Dower wrote:
> > On 30Jan2016 0645, Serhiy Storchaka wrote:
> >> $ ./python -m timeit -s "import codecs; from encodings.cp437 import
> >> decoding_table" -- "codecs.charmap_build(decoding_table)"
> >> 100000 loops, best of 3: 4.36 usec per loop
> >>
> >> Getting rid from charmap_build() would save you at most 4.4 microseconds
> >> per encoding. 0.0005 seconds if you have imported *all* standard
> >> encodings!
> >
> > Just as happy to be proven wrong. Perhaps I misinterpreted my original
> > profiling and then, embarrassingly, ran with the result for a long time
> > without retesting.
>
> AFAIK the most time is spent in system calls like stat or open.
> Archiving the stdlib into the ZIP file and using zipimport can decrease
> Python startup time (perhaps there is an open issue about this).
>

Check the archives, but  I did trying freezing the entire stdlib and it
didn't really make a difference in startup, so I don't know if this still
holds true anymore.

At this point I think all of our knowledge of what takes the most amount of
time during startup is outdated and someone should try to really profile
the whole thing to see where the hotspots are (e.g., is it stat calls from
imports, is it actually some specific function, is it just so many little
things adding up to a big thing, etc.).
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