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bpo-39028: Performance enhancement in keyword extraction (GH-17576) 

All keywords should first be checked for pointer identity. Only
after that failed for all keywords (unlikely) should unicode
equality be used.
The original code would call unicode equality on any non-matching
keyword argument. Meaning calling it often e.g. when a function
has many kwargs but only the last one is provided.
This commit is contained in:
Sebastian Berg 2019-12-18 00:51:22 -06:00 committed by Inada Naoki
parent 50d4f12958
commit 75bb07e92b
2 changed files with 8 additions and 3 deletions
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1
Misc/NEWS.d/next/Core and Builtins/2019-12-17-23-20-51.bpo-39028.SND4TB.rst Normal file
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@ -0,0 +1 @@
Slightly improve the speed of keyword argument parsing with many kwargs by strengthening the assumption that kwargs are interned strings.

10
Python/getargs.c
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@ -2053,14 +2053,18 @@ find_keyword(PyObject *kwnames, PyObject *const *kwstack, PyObject *key)
Py_ssize_t i, nkwargs;
nkwargs = PyTuple_GET_SIZE(kwnames);
for (i=0; i < nkwargs; i++) {
for (i = 0; i < nkwargs; i++) {
PyObject *kwname = PyTuple_GET_ITEM(kwnames, i);
/* ptr==ptr should match in most cases since keyword keys
should be interned strings */
/* kwname == key will normally find a match in since keyword keys
should be interned strings; if not retry below in a new loop. */
if (kwname == key) {
return kwstack[i];
}
}
for (i = 0; i < nkwargs; i++) {
PyObject *kwname = PyTuple_GET_ITEM(kwnames, i);
assert(PyUnicode_Check(kwname));
if (_PyUnicode_EQ(kwname, key)) {
return kwstack[i];