2017-07-21 4:52 GMT+02:00 Nick Coghlan <ncoghlan@gmail.com>:
On 21 July 2017 at 12:44, Nick Coghlan <ncoghlan@gmail.com> wrote:
> We can separately measure the cost of unmarshalling the code object:
>
> $ python3 -m perf timeit -s "import typing; from marshal import loads; from
> importlib.util import cache_from_source; cache =
> cache_from_source(typing.__file__); data = open(cache, 'rb').read()[12:]"
> "loads(data)"
> .....................
> Mean +- std dev: 286 us +- 4 us

Slight adjustment here, as the cost of locating the cached bytecode
and reading it from disk should really be accounted for in each
iteration:

$ python3 -m perf timeit -s "import typing; from marshal import loads;
from importlib.util import cache_from_source" "cache =
cache_from_source(typing.__spec__.origin); data = open(cache,
'rb').read()[12:]; loads(data)"
.....................
Mean +- std dev: 337 us +- 8 us

That will have a bigger impact when loading from spinning disk or a
network drive, but it's fairly negligible when loading from a local
SSD or an already primed filesystem cache.

Cheers,
Nick.

--
Nick Coghlan   |   ncoghlan@gmail.com   |   Brisbane, Australia
Thanks for your tests, Nick. It's quite evident that the marshal code cannot improve the situation, so I regret from my proposal.

I took a look at the typing module, and there are some small things that can be optimized, but it'll not change the overall situation unfortunately.

Code execution can be improved. :) However, it requires a massive amount of time experimenting...

Bests,
Cesare

Mail priva di virus. www.avast.com