[Python-Dev] VM imaging based launch optimizations for CPython?

["Martin v. Löwis"]

>     Of course, you still have the actual interpretation of
>     the top-level module code - if it's not the marshalling
>     but this part that actually costs performance, this
>     efficient marshalling algorithm won't help. It would be
>     interesting to find out which modules have a particularly
>     high startup cost - perhaps they can be rewritten
> 
> 
> I am afraid this is the case.

Is that an unfounded or a founded fear? IOW, do you have hard numbers
proving that it is the actual interpretation time (rather than the
marshaling time) that causes the majority of the startup cost?

> I hope we could marshal an arbitary
> application state (not even Python specific) into a fast loading dump
> file (hibernation/snapshot).

I understand that this is what you want to get. I'm proposing that
there might be a different approach to achieve a similar speedup.

> logging - defines lots of classes which are used only if they are
> specified by logging options. I once hacked this for my personal use to
> be little lighter.

So what speedup did you gain by rewriting it? (i.e. how many
microseconds did "import logging" take before, how much afterwards?)
How much of it was parsing/unmarshaling, and how much time byte
code interpretation? Of the byte code interpretation, what opcodes
in particular?

> urllib - particular heavy, imports httplib, ftplib and stuff even if it
> is not used

Same questions here. This doesn't sound like any heavy computation is
being done during startup.

> Nokia has just released Python 2.5 based PyS60. I think we'll come back
> this after a while with a nice generic profiler which will tell the
> import cost.

Looking forward to hear your numbers!

Regards,
Martin