On Wed, Jan 15, 2020 at 06:05:42PM +0100, Miro Hrončok wrote: > ### File types (and bytecode caches) > > The orthogonal dimension is the file type. Python standard library > contains directories with both "extension modules" (written in C > (usually) and compiled to `*.cpython-38-x86_64-linux-gnu.so` shared > object file) and "pure Python" modules (written in Python and saved > as `*.py` source file). > > Each pure Python module comes in 4 files: > > - `module.py` -- the source > - `__pycache__/module.cpython-38.pyc` -- regular (not optimized) bytecode > cache > - `__pycache__/module.cpython-38.opt-1.pyc` -- optimized bytecode cache > (level 1) > - `__pycache__/module.cpython-38.opt-2.pyc` -- optimized bytecode cache > (level 2)
I suspect that the difference in speed between loading various .pyc files is negligible. Do you have actual benchmarks for this? > ### Solution 5: Stop shipping mandatory bytecode cache > > This solution sounds simple: We do no longer ship the bytecode cache > mandatorily. Technically, we move the `.pyc` files to a subpackage > of `python3-libs` (or three different subpackages, that is not > important here). And we only *Recommend* them from `python3-libs` -- > by default, the users get them, but for space critical Fedora > flavors (such as container images) the maintainers can opt-out and > so can the powerusers. > > This would **save 18.6 MiB / 50%** -- quite a lot. > > However, as said earlier, if the bytecode cache files are not there, > Python attempts to create them upon first import. That can result in > several problems, here we will try to propose how to workaround > them. Below using a flag file in each __pycache__ directory is suggested. What about a different route: having a flag file for all descendants of a directory? For example, /usr/lib/python3.8/.dont_write_bytecode would cover all modules under /usr/lib/python3.8/. If a .pyc file is present, python could still make use of it. This would be a nicer solution because it wouldn't require modifying individual packages, but would still avoid the selinux issues and slowdowns from failed attempts to write the optimized files. The __pycache__ files wouldn't need to exist at all. Zbyszek _______________________________________________ python-devel mailing list -- python-devel@lists.fedoraproject.org To unsubscribe send an email to python-devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/python-devel@lists.fedoraproject.org
