Add comment to explain the implications of not sorting keywords#3331
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In Python 3.6, sorted() was removed from _make_key() for the lru_cache and instead rely on guaranteed keyword argument order preservation. This makes keyword argument handling faster but it also causes multiple callers with a different keyword argument order to be cached as separate items. Depending on your point of view, this is either a performance regression (increased number of cache misses) or a performance enhancement (faster computation of keys).
jimmylai pushed a commit to jimmylai/cpython that referenced this pull request Sep 5, 2017
* 'master' of https://github.com/python/cpython: (32 commits) Conceptually, roots is a set. Also searching it as a set is a tiny bit faster (python#3338) bpo-31343: Include sys/sysmacros.h (python#3318) bpo-30102: Call OPENSSL_add_all_algorithms_noconf (python#3112) Prevent a few make suspicious warnings. (python#3341) Include additional changes to support blurbified NEWS (python#3340) Simplify NEWS entry to prevent suspicious warnings. (python#3339) bpo-31347: _PyObject_FastCall_Prepend: do not call memcpy if args might not be null (python#3329) Revert "bpo-17852: Maintain a list of BufferedWriter objects. Flush them on exit. (python#1908)" (python#3337) bpo-17852: Maintain a list of BufferedWriter objects. Flush them on exit. (python#1908) Fix terminology in comment and add more design rationale. (python#3335) Add comment to explain the implications of not sorting keywords (python#3331) bpo-31170: Update libexpat from 2.2.3 to 2.2.4 (python#3315) bpo-28411: Remove "modules" field from Py_InterpreterState. (python#1638) random_triangular: sqrt() is more accurate than **0.5 (python#3317) Travis: use ccache (python#3307) remove IRIX support (closes bpo-31341) (python#3310) Code clean-up. Remove unnecessary pre-increment before the loop starts. (python#3312) Regen Moduls/clinic/_ssl.c.h (pythonGH-3320) bpo-30502: Fix handling of long oids in ssl. (python#2909) Cache externals, depending on changes to PCbuild (python#3308) ...
GadgetSteve pushed a commit to GadgetSteve/cpython that referenced this pull request Sep 10, 2017
…on#3331) In Python 3.6, sorted() was removed from _make_key() for the lru_cache and instead rely on guaranteed keyword argument order preservation. This makes keyword argument handling faster but it also causes multiple callers with a different keyword argument order to be cached as separate items. Depending on your point of view, this is either a performance regression (increased number of cache misses) or a performance enhancement (faster computation of keys).
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In Python 3.6, sorted() was removed from _make_key() for the lru_cache and instead rely on guaranteed keyword argument order preservation. This makes keyword argument handling faster but it also causes multiple callers with a different keyword argument order to be cached as separate items. Depending on your point of view, this is either a performance regression (increased number of cache misses) or a performance enhancement (faster computation of keys).