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bpo-40521: Make slice cache per-interpreter #20637

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Merged
merged 1 commit into from
Jun 4, 2020
Merged

bpo-40521: Make slice cache per-interpreter #20637

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4 changes: 4 additions & 0 deletions Include/internal/pycore_interp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -187,6 +187,10 @@ struct _is {
#endif
struct _Py_tuple_state tuple;
struct _Py_float_state float_state;

/* Using a cache is very effective since typically only a single slice is
created and then deleted again. */
PySliceObject *slice_cache;
};

/* Used by _PyImport_Cleanup() */
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2 changes: 1 addition & 1 deletion Include/internal/pycore_pylifecycle.h
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Expand Up @@ -65,7 +65,7 @@ extern void _PyList_Fini(void);
extern void _PySet_Fini(void);
extern void _PyBytes_Fini(void);
extern void _PyFloat_Fini(PyThreadState *tstate);
extern void _PySlice_Fini(void);
extern void _PySlice_Fini(PyThreadState *tstate);
extern void _PyAsyncGen_Fini(void);

extern void PyOS_FiniInterrupts(void);
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5 changes: 3 additions & 2 deletions Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst
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@@ -1,2 +1,3 @@
Tuple free lists, empty tuple singleton, and float free list are no longer
shared by all interpreters: each interpreter now its own free lists.
The tuple free lists, the empty tuple singleton, the float free list, and the
slice cache are no longer shared by all interpreters: each interpreter now has
its own free lists and caches.
29 changes: 15 additions & 14 deletions Objects/sliceobject.c
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Expand Up @@ -15,7 +15,7 @@ this type and there is exactly one in existence.

#include "Python.h"
#include "pycore_abstract.h" // _PyIndex_Check()
#include "pycore_object.h"
#include "pycore_object.h" // _PyObject_GC_TRACK()
#include "structmember.h" // PyMemberDef

static PyObject *
Expand Down Expand Up @@ -95,16 +95,13 @@ PyObject _Py_EllipsisObject = {

/* Slice object implementation */

/* Using a cache is very effective since typically only a single slice is
* created and then deleted again
*/
static PySliceObject *slice_cache = NULL;

void _PySlice_Fini(void)
void _PySlice_Fini(PyThreadState *tstate)
{
PySliceObject *obj = slice_cache;
PyInterpreterState *interp = tstate->interp;
PySliceObject *obj = interp->slice_cache;
if (obj != NULL) {
slice_cache = NULL;
interp->slice_cache = NULL;
PyObject_GC_Del(obj);
}
}
Expand All @@ -116,10 +113,11 @@ void _PySlice_Fini(void)
PyObject *
PySlice_New(PyObject *start, PyObject *stop, PyObject *step)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
PySliceObject *obj;
if (slice_cache != NULL) {
obj = slice_cache;
slice_cache = NULL;
if (interp->slice_cache != NULL) {
obj = interp->slice_cache;
interp->slice_cache = NULL;
_Py_NewReference((PyObject *)obj);
} else {
obj = PyObject_GC_New(PySliceObject, &PySlice_Type);
Expand Down Expand Up @@ -324,14 +322,17 @@ Create a slice object. This is used for extended slicing (e.g. a[0:10:2]).");
static void
slice_dealloc(PySliceObject *r)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
_PyObject_GC_UNTRACK(r);
Py_DECREF(r->step);
Py_DECREF(r->start);
Py_DECREF(r->stop);
if (slice_cache == NULL)
slice_cache = r;
else
if (interp->slice_cache == NULL) {
interp->slice_cache = r;
}
else {
PyObject_GC_Del(r);
}
}

static PyObject *
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2 changes: 1 addition & 1 deletion Python/pylifecycle.c
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Expand Up @@ -1265,9 +1265,9 @@ finalize_interp_types(PyThreadState *tstate, int is_main_interp)

if (is_main_interp) {
_PyDict_Fini();
_PySlice_Fini();
}

_PySlice_Fini(tstate);
_PyWarnings_Fini(tstate->interp);

if (is_main_interp) {
Expand Down