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