Issue 28596: on Android _bootlocale on startup relies on too many library modules

Android does not have langinfo.h and this results in _bootlocale importing locale on startup (see issue 26928).

IMHO it is not acceptable to fallback to locale.py if CODESET is not available (in answer to Victor question in msg199367), because there are now two code paths to investigate weird bugs such as the one described by Antoine in issue 9548. Also note that Android platforms have a slow processor and limited RAM size, so they would strongly benefit from a startup sequence avoiding the imports made by the locale module. Since there is already a _bootlocale module, what are now the objections to implement the patch Antoine has proposed in issue 9548 ?

Nosying people from issue 9548.

Here's my try: force UTF-8 on Android as explained in msg281110. sys.getfilesystemencoding() is already UTF-8 since issue22747.

Testing:
1. Starting up time 0.18~0.19s => 0.11~0.12s, on Android 6.0, ASUS ZE500KL (Qualcomm MSM8916 QuadCore 1.2GHz)
2. test_site passes

Version 2 - use sys.implementation._multiarch to determine whether it's Android or not

I created the issue #28740: Add sys.getandroidapilevel().

Patch version 3, using sys.getandroidapilevel()

Thanks Victor. Here's new patch, which uses hasattr

android-locale-utf8.patch LGTM, but I added minor comments on the review.

I would prefer to let Xavier merges this one, since he can test it.

This is a performance issue. I will look at it shortly.

Patch version 5, updated comments. Thanks for all of those feedbacks :)

New changeset 1756beed417c by Xavier de Gaye in branch 'default':
Issue #28596: The preferred encoding is UTF-8 on Android.
https://hg.python.org/cpython/rev/1756beed417c

Closing the issue. Thanks for the patch Chi Hsuan Yen.

stage: patch review -> resolved

messages: + msg282616

messages: + msg282386

messages: + msg282339

messages: + msg281153

nosy: + yan12125
messages: + msg281131

keywords: + patch