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gh-150942: Optimize stringlib split/splitlines with _PyList_AppendTakeRef #155922

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Merged
corona10 merged 2 commits into from
Aug 17, 2026
+5 −11
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gh-150942: Optimize stringlib split/splitlines with _PyList_AppendTakeRef #155922

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gh-150942: Optimize stringlib split/splitlines with _PyList_AppendTak…
danielKim614 Aug 17, 2026
f3fd338
Delete Misc/NEWS.d/next/Core_and_Builtins/2026-08-17-14-00-00.gh-issu…
corona10 Aug 17, 2026
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16 changes: 5 additions & 11 deletions Objects/stringlib/split.h
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@
#error must include "stringlib/fastsearch.h" before including this module
#endif

#include "pycore_list.h" // _PyList_AppendTakeRef()

/* Overallocate the initial list to reduce the number of reallocs for small
split sizes. Eg, "A A A A A A A A A A".split() (10 elements) has three
resizes, to sizes 4, 8, then 16. Most observed string splits are for human
Expand All @@ -22,12 +24,8 @@
(right) - (left)); \
if (sub == NULL) \
goto onError; \
if (PyList_Append(list, sub)) { \
Py_DECREF(sub); \
goto onError; \
} \
else \
Py_DECREF(sub);
if (_PyList_AppendTakeRef((PyListObject *)list, sub)) \
goto onError;

#define SPLIT_ADD(data, left, right) { \
sub = STRINGLIB_NEW((data) + (left), \
Expand All @@ -37,12 +35,8 @@
if (count < MAX_PREALLOC) { \
PyList_SET_ITEM(list, count, sub); \
} else { \
if (PyList_Append(list, sub)) { \
Py_DECREF(sub); \
if (_PyList_AppendTakeRef((PyListObject *)list, sub)) \
goto onError; \
} \
else \
Py_DECREF(sub); \
} \
count++; }

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