Port zoneinfo module to use module state #99138

sobolevn · 2022-11-05T18:34:32Z

Feature or enhancement

Following https://github.com/ericsnowcurrently/multi-core-python/wiki/0-The-Plan we need to convert _zoneinfo to use module state.

Pitch

Right now there are several global objects:

cpython/Modules/_zoneinfo.c

Lines 23 to 25 in 47ab848

    
           static PyObject *io_open = NULL; 
        
           static PyObject *_tzpath_find_tzfile = NULL; 
        
           static PyObject *_common_mod = NULL;

and

cpython/Modules/_zoneinfo.c

Lines 96 to 101 in 47ab848

    
           static PyObject *TIMEDELTA_CACHE = NULL; 
        
           static PyObject *ZONEINFO_WEAK_CACHE = NULL; 
        
           static StrongCacheNode *ZONEINFO_STRONG_CACHE = NULL; 
        
           static size_t ZONEINFO_STRONG_CACHE_MAX_SIZE = 8; 
        
           static _ttinfo NO_TTINFO = {NULL, NULL, NULL, 0};

And one static type definition:

cpython/Modules/_zoneinfo.c

Line 93 in 47ab848

static PyTypeObject PyZoneInfo_ZoneInfoType;

If this is indeed planned to be fixed, I would love to work on it.

The text was updated successfully, but these errors were encountered:

corona10 · 2022-11-06T04:00:33Z

I would like to listen to the opinion of the original author @pganssle

pganssle · 2022-11-06T04:27:09Z

I think I originally planned to do this but it made the implementation a bit more complicated and maybe all the pieces to do it weren't in place / stable yet, and after talking to Eric it seemed like it wasn't time sensitive back then.

I don't remember any major show stoppers, just, "This is hard enough, I should spend my effort points on other stuff that matters more." Which isn't to say there aren't show stoppers, just that I don't remember any.

I think the big thing to be aware of when doing this is that the weak cache is not for performance, it is guaranteeing specific semantics, detailed in PEP 615. So hopefully it is possible to do this while maintaining the relevant guarantees.

erlend-aasland · 2022-11-06T21:51:41Z

FWIW, I have a two year old branch (now rebased onto main) that converts PyZoneInfo_ZoneInfoType to a heap type and establishes a global state struct:

https://github.com/erlend-aasland/cpython/pull/new/isolate-zoneinfo

sobolevn added type-feature A feature request or enhancement expert-subinterpreters labels Nov 5, 2022

sobolevn self-assigned this Nov 5, 2022

Port zoneinfo module to use module state #99138

Port zoneinfo module to use module state #99138

sobolevn commented Nov 5, 2022

corona10 commented Nov 6, 2022 •

edited

pganssle commented Nov 6, 2022 •

edited

erlend-aasland commented Nov 6, 2022 •

edited

Port zoneinfo module to use module state #99138

Port zoneinfo module to use module state #99138

Comments

sobolevn commented Nov 5, 2022

Feature or enhancement

Pitch

corona10 commented Nov 6, 2022 • edited

pganssle commented Nov 6, 2022 • edited

erlend-aasland commented Nov 6, 2022 • edited

corona10 commented Nov 6, 2022 •

edited

pganssle commented Nov 6, 2022 •

edited

erlend-aasland commented Nov 6, 2022 •

edited