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Inconsistency in whether function setters call _PyFunction_SetVersion #109998
Description
Bug report
The function object has a number of settable attributes. For the following, setting the value calls _PyFunction_SetVersion(op, 0):
__defaults____kwdefaults____code____annotations__
But for the following, there is no such call:
__dict____name____qualname____type_params__
I don't think any of these four should affect the interpreter loop, but neither should __annotations__. Should these setters also set the version for consistency, or should __annotations__ not set it as changing the annotations shouldn't affect the runtime?
cc @markshannon who added this in #27078.
Activity
gvanrossum commentedon Mar 18, 2024
The
func_versionfield is intended for use by the PEP 659 adaptive specializing interpreter and the Tier 2 optimizer (and JIT) only. You're right that the fields in the second list (as well as "plain" function attribute assignments likef.foo = 42) don't affect the specializer at all. You're also right that__annotations__doesn't affect it! IMO that attribute should not call_PyFunction_SetVersion(); I think the call was added by mistake.Separately, I think that the specializer should just not bother picking a new version for functions which have a "critical" attribute (the first list, less
__annotations__) changed. Setting those is pretty obscure, and I think it's fine if the interpreter falls back to unspecialized Tier 1 bytecode for those cases. We could do that by changing_PyFunction_GetVersionForCurrentState()to just leave it zero. (Or just get rid of that function and usefunc->func_versiondirectly in the specializer.)TBH, I would also be open to making the critical attributes read-only, although I suspect that PyTorch might be using this feature (and then the idea would be dead on arrival).
gvanrossum commentedon Mar 18, 2024
PS.
__closure__also belongs in the "critical" list. (And it does call_PyFunction_SetVersion().)gh-117045: Add code object to function version cache (#117028)
pythongh-117045: Add code object to function version cache (python#11…
Squashed commit of the following:
Squashed commit of the following:
pythongh-117045: Add code object to function version cache (python#11…