[Pythonmac-SIG] Slow loading of modules

[Jack Jansen]

On zaterdag, feb 22, 2003, at 12:30 Europe/Amsterdam, Doug Wyatt wrote:
> Try this:
>
> /python.exe -c "import Carbon.AE" & ; sample python.exe 10 10
>
> and then look at the sample log written to /tmp

Doug,
thanks a lot!!!! I looked at this, and it turns out most of the time is 
spent in _dyld_link_module, and specifically in _resolve_undefineds and 
_relocate_modules_being_linked.

On a hunch I disabled prebinding for the main executable, which I had 
enabled only a couple of weeks ago. The results are staggering:

- With prebinding:
% time ./python.exe -c "pass"
0.130u 0.130s 0:00.62 41.9%     0+0k 24+3io 0pf+0w
% time ./python.exe -c "import _AE"
8.140u 0.170s 0:08.54 97.3%     0+0k 8+4io 0pf+0w

- Without prebinding:
% time ./python.exe -c "pass"
0.100u 0.130s 0:00.28 82.1%     0+0k 0+0io 0pf+0w
% time ./python.exe -c "import _AE"
1.130u 0.110s 0:01.39 89.2%     0+0k 0+1io 0pf+0w

I definitely do remember a speedup for the initial empty startup (I did 
actually test that -prebind made a difference:-), so the fact that even 
that is now worse may be an artifact of changes in site.py or something.

It appears that a program that does a lot of dynamic loading of code is 
worse off when linked prebound. Does anyone have a good explanation for 
this, or should I file an Apple bug report (even only suggesting that 
they document this)?
--
- Jack Jansen        <Jack.Jansen@oratrix.com>        
http://www.cwi.nl/~jack -
- If I can't dance I don't want to be part of your revolution -- Emma 
Goldman -