On 2016-01-18 5:43 PM, Victor Stinner wrote:
Is someone opposed to this PEP 509?
The main complain was the change on the public Python API, but the PEP
doesn't change the Python API anymore.
I'm not aware of any remaining issue on this PEP.
Victor,
I've been experimenting with the PEP to implement a per-opcode
cache in ceval loop (I'll share my progress on that in a few
days). This allows to significantly speedup LOAD_GLOBAL and
LOAD_METHOD opcodes, to the point, where they don't require
any dict lookups at all. Some macro-benchmarks (such as
chameleon_v2) demonstrate impressive ~10% performance boost.
I rely on your dict->ma_version to implement cache invalidation.
However, besides guarding against version change, I also want
to guard against the dict being swapped for another dict, to
avoid situations like this:
def foo():
print(bar)
exec(foo.__code__, {'bar': 1}, {})
exec(foo.__code__, {'bar': 2}, {})
What I propose is to add a pointer "ma_extra" (same 64bits),
which will be set to NULL for most dict instances (instead of
ma_version). "ma_extra" can then point to a struct that has a
globally unique dict ID (uint64), and a version tag (unit64).
A macro like PyDict_GET_ID and PyDict_GET_VERSION could then
efficiently fetch the version/unique ID of the dict for guards.
"ma_extra" would also make it easier for us to extend dicts
in the future.
Yury
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
https://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
