On 9/28/2021 8:36 AM, Victor Stinner wrote:
On Mon, Sep 27, 2021 at 6:58 PM Eric Snow <ericsnowcurren...@gmail.com> wrote:
We've frozen most of the stdlib modules imported during "python -c
pass" [1][2], to make startup a bit faster. Import of those modules
is controlled by "-X frozen_modules=[on|off]". Currently it defaults
to "off" but we'd like to default to "on". The blocker is the impact
on contributors. I expect many will make changes to a stdlib module
and then puzzle over why those changes aren't getting used. That's an
annoyance we can avoid, which is the point of this thread.
Possible solutions:
1. always default to "on" (the annoyance for contributors isn't big enough?)
2. default to "on" if it's a PGO build (and "off" otherwise)
3. default to "on" unless running from the source tree
Thoughts?
Honestly, for me, #1: always on, is the most reasonable choice.
I dislike when Python behaves differently depending on subtle things
like "was it built with optimizations" or "is Python started from its
source tree"?
When I built Python without optimization and/or from its source tree,
I do that to debug an issue. If the bug goes away in this case, it can
waste my time.
So I prefer to teach everybody how to use "-X frozen_modules=off" if
they want to hack the stdlib for their greatest pleasure. I prefer
that such special use case requires an opt-in option, the special use
case is not special enough to be the default.
I agree with Victor here: I'd rather have #1.
As a compromise, how about go with #1, but print a warning if python
detects that it's not built with optimizations or is run from a source
tree (the conditions in #2 and #3)? The warning could suggest running
with "-X frozen_modules=off". I realize that it will probably be ignored
over time, but maybe it will provide enough of a reminder if someone is
debugging and sees the warning.
Eric
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