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gh-148085: datetime cache time module lookups #148088

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Merged
StanFromIreland merged 16 commits into from
Aug 29, 2026
Merged

gh-148085: datetime cache time module lookups #148088

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36c494b
simple caching
maurycy Apr 4, 2026
48e9ea1
news
maurycy Apr 4, 2026
ae32bfd
oops, lint
maurycy Apr 4, 2026
7e7b739
lazy
maurycy Apr 4, 2026
cd247ca
i thought it existed... ok, now. no warnings?
maurycy Apr 4, 2026
2f3dbe0
mv to library
maurycy Apr 4, 2026
d3944fe
stan is right; just call PyTime_Time directly?
maurycy Apr 6, 2026
33c64f2
revert lazy
maurycy Apr 7, 2026
ff27dc4
news
maurycy Apr 7, 2026
056cf08
mv the comment
maurycy Apr 8, 2026
e00aa62
mea culpa!
maurycy Apr 8, 2026
170a3f0
do not lie in the news
maurycy May 17, 2026
7751fc6
line below
maurycy May 17, 2026
75f3992
Update Misc/NEWS.d/next/Library/2026-04-04-14-25-43.gh-issue-148085.o…
maurycy Aug 28, 2026
bab8283
Update Modules/_datetimemodule.c
maurycy Aug 28, 2026
e206500
fix
maurycy Aug 28, 2026
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4 changes: 4 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2026-04-04-14-25-43.gh-issue-148085.o97yTo.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
Cache ``time.time``, ``time.struct_time``, and ``time.strftime`` imports,
speeding up :meth:`~datetime.date.timetuple` and
:meth:`~datetime.date.strftime` by up to 2x. Patch by Maurycy
Pawłowski-Wieroński.
72 changes: 56 additions & 16 deletions Modules/_datetimemodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,10 @@ typedef struct {

/* The interned Unix epoch datetime instance */
PyObject *epoch;

PyObject *time_time;
PyObject *time_struct_time;
PyObject *time_strftime;
} datetime_state;

/* The module has a fixed number of static objects, due to being exposed
Expand Down Expand Up @@ -1879,10 +1883,19 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
assert(object && format && timetuple);
assert(PyUnicode_Check(format));

PyObject *strftime = PyImport_ImportModuleAttrString("time", "strftime");
if (strftime == NULL) {
PyObject *current_mod = NULL;
datetime_state *st = GET_CURRENT_STATE(current_mod);
if (st == NULL) {
return NULL;
}
if (st->time_strftime == NULL) {
st->time_strftime = PyImport_ImportModuleAttrString("time", "strftime");
if (st->time_strftime == NULL) {
RELEASE_CURRENT_STATE(st, current_mod);
return NULL;
}
}
PyObject *strftime = st->time_strftime;

/* Scan the input format, looking for %z/%Z/%f escapes, building
* a new format. Since computing the replacements for those codes
Expand Down Expand Up @@ -2042,7 +2055,7 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
Py_XDECREF(zreplacement);
Py_XDECREF(colonzreplacement);
Py_XDECREF(Zreplacement);
Py_XDECREF(strftime);
RELEASE_CURRENT_STATE(st, current_mod);
return result;

Error:
Expand All @@ -2059,13 +2072,20 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
static PyObject *
time_time(void)
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{
PyObject *result = NULL;
PyObject *time = PyImport_ImportModuleAttrString("time", "time");

if (time != NULL) {
result = PyObject_CallNoArgs(time);
Py_DECREF(time);
PyObject *current_mod = NULL;
datetime_state *st = GET_CURRENT_STATE(current_mod);
if (st == NULL) {
return NULL;
}
if (st->time_time == NULL) {
st->time_time = PyImport_ImportModuleAttrString("time", "time");
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if (st->time_time == NULL) {
RELEASE_CURRENT_STATE(st, current_mod);
return NULL;
}
}
PyObject *result = PyObject_CallNoArgs(st->time_time);
RELEASE_CURRENT_STATE(st, current_mod);
return result;
}

Expand All @@ -2075,21 +2095,27 @@ time_time(void)
static PyObject *
build_struct_time(int y, int m, int d, int hh, int mm, int ss, int dstflag)
{
PyObject *struct_time;
PyObject *result;

struct_time = PyImport_ImportModuleAttrString("time", "struct_time");
if (struct_time == NULL) {
PyObject *current_mod = NULL;
datetime_state *st = GET_CURRENT_STATE(current_mod);
if (st == NULL) {
return NULL;
}
if (st->time_struct_time == NULL) {
st->time_struct_time = PyImport_ImportModuleAttrString("time", "struct_time");
if (st->time_struct_time == NULL) {
RELEASE_CURRENT_STATE(st, current_mod);
return NULL;
}
}

result = PyObject_CallFunction(struct_time, "((iiiiiiiii))",
PyObject *result = PyObject_CallFunction(st->time_struct_time,
"((iiiiiiiii))",
y, m, d,
hh, mm, ss,
weekday(y, m, d),
days_before_month(y, m) + d,
dstflag);
Py_DECREF(struct_time);
RELEASE_CURRENT_STATE(st, current_mod);
return result;
}

Expand Down Expand Up @@ -7414,6 +7440,9 @@ init_state(datetime_state *st, PyObject *module, PyObject *old_module)
.us_per_week = Py_NewRef(st_old->us_per_week),
.seconds_per_day = Py_NewRef(st_old->seconds_per_day),
.epoch = Py_NewRef(st_old->epoch),
.time_time = Py_XNewRef(st_old->time_time),
.time_struct_time = Py_XNewRef(st_old->time_struct_time),
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.time_strftime = Py_XNewRef(st_old->time_strftime),
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};
return 0;
}
Expand Down Expand Up @@ -7458,6 +7487,10 @@ init_state(datetime_state *st, PyObject *module, PyObject *old_module)
return -1;
}

st->time_time = NULL;
st->time_struct_time = NULL;
st->time_strftime = NULL;

return 0;
}

Expand All @@ -7467,6 +7500,10 @@ traverse_state(datetime_state *st, visitproc visit, void *arg)
/* heap types */
Py_VISIT(st->isocalendar_date_type);

Py_VISIT(st->time_time);
Py_VISIT(st->time_struct_time);
Py_VISIT(st->time_strftime);

return 0;
}

Expand All @@ -7482,6 +7519,9 @@ clear_state(datetime_state *st)
Py_CLEAR(st->us_per_week);
Py_CLEAR(st->seconds_per_day);
Py_CLEAR(st->epoch);
Py_CLEAR(st->time_time);
Py_CLEAR(st->time_struct_time);
Py_CLEAR(st->time_strftime);
return 0;
}

Expand Down
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