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Creation of an internal decimal context for _pylong has side effects on decimal #123284
Closed as not planned
Description
Bug report
Bug description:
The _decimal module was recently fixed in #123243. I also found that _pylong leaks globals due to the creation of a global context to use as a local context:
_unbounded_dec_context = decimal.getcontext().copy()
_unbounded_dec_context.prec = decimal.MAX_PREC
_unbounded_dec_context.Emax = decimal.MAX_EMAX
_unbounded_dec_context.Emin = decimal.MIN_EMIN
_unbounded_dec_context.traps[decimal.Inexact] = 1 # sanity checkThis context is used as with decimal.localcontext(_unbounded_dec_context). On the other hand decimal.getcontext().copy() returns a copy of the decimal context for the current thread (or set it to decimal.DefaultContext if none exists). Instead of setting it like that, I suggest that we construct a decimal.Context() object directly in _pylong instead of possibly polluting the decimal module (whether it's the C or the python implementation).
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Activity
[-]Creation of an internal decimal context for `_pylong` has side effects on `decimal` (and refleaks)[/-][+]Creation of an internal decimal context for `_pylong` has side effects on `decimal`[/+]vstinner commentedon Sep 5, 2024
How do you see such leak?
picnixz commentedon Sep 5, 2024
I just used
./python -X showrefcounts -c 'import _pylong'. I don't really know if it's the_pylongmodule itself that leaks or if it's thedecimalmodule that leaks becausedecimal.getcontext()was called.What I however know is that there is a side-effect on
decimalbecause_pylongcallsdecimal.getcontext()and thus sets the decimal default's context. I'm not really sure whether it's an issue or not, but I was just looking at all./python -X showrefcounts -c 'import MODULE'for every module inLibto see whether a module leaked or not. Feel free to close if you think this is a non-issue though.vstinner commentedon Sep 5, 2024
The problem is unrelated to
_pylong, but related to decimal:picnixz commentedon Sep 5, 2024
Ok, one interrogation confirmed. I'll try to see what I can do tomorrow (not sure if I'll be able to though).
picnixz commentedon Sep 6, 2024
So the reference leaks will be fixed by another PR. I won't bother about setting the decimal's default thread context