bpo-40521: Make tuple free list per-interpreter (GH-20247)
Each interpreter now has its own tuple free lists:
* Move tuple numfree and free_list arrays into PyInterpreterState.
* Define PyTuple_MAXSAVESIZE and PyTuple_MAXFREELIST macros in
pycore_interp.h.
* Add _Py_tuple_state structure. Pass it explicitly to tuple_alloc().
* Add tstate parameter to _PyTuple_ClearFreeList()
* Each interpreter now has its own empty tuple singleton.
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index 43706c2..951cd1f 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -14,28 +14,6 @@
#include "clinic/tupleobject.c.h"
-/* Speed optimization to avoid frequent malloc/free of small tuples */
-#ifndef PyTuple_MAXSAVESIZE
-#define PyTuple_MAXSAVESIZE 20 /* Largest tuple to save on free list */
-#endif
-#ifndef PyTuple_MAXFREELIST
-#define PyTuple_MAXFREELIST 2000 /* Maximum number of tuples of each size to save */
-#endif
-
-/* bpo-40521: tuple free lists are shared by all interpreters. */
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-# undef PyTuple_MAXSAVESIZE
-# define PyTuple_MAXSAVESIZE 0
-#endif
-
-#if PyTuple_MAXSAVESIZE > 0
-/* Entries 1 up to PyTuple_MAXSAVESIZE are free lists, entry 0 is the empty
- tuple () of which at most one instance will be allocated.
-*/
-static PyTupleObject *free_list[PyTuple_MAXSAVESIZE];
-static int numfree[PyTuple_MAXSAVESIZE];
-#endif
-
static inline void
tuple_gc_track(PyTupleObject *op)
{
@@ -47,14 +25,14 @@
_PyTuple_DebugMallocStats(FILE *out)
{
#if PyTuple_MAXSAVESIZE > 0
- int i;
- char buf[128];
- for (i = 1; i < PyTuple_MAXSAVESIZE; i++) {
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
+ for (int i = 1; i < PyTuple_MAXSAVESIZE; i++) {
+ char buf[128];
PyOS_snprintf(buf, sizeof(buf),
"free %d-sized PyTupleObject", i);
- _PyDebugAllocatorStats(out,
- buf,
- numfree[i], _PyObject_VAR_SIZE(&PyTuple_Type, i));
+ _PyDebugAllocatorStats(out, buf, state->numfree[i],
+ _PyObject_VAR_SIZE(&PyTuple_Type, i));
}
#endif
}
@@ -68,7 +46,7 @@
which wraps this function).
*/
static PyTupleObject *
-tuple_alloc(Py_ssize_t size)
+tuple_alloc(struct _Py_tuple_state *state, Py_ssize_t size)
{
PyTupleObject *op;
if (size < 0) {
@@ -76,10 +54,10 @@
return NULL;
}
#if PyTuple_MAXSAVESIZE > 0
- if (size < PyTuple_MAXSAVESIZE && (op = free_list[size]) != NULL) {
+ if (size < PyTuple_MAXSAVESIZE && (op = state->free_list[size]) != NULL) {
assert(size != 0);
- free_list[size] = (PyTupleObject *) op->ob_item[0];
- numfree[size]--;
+ state->free_list[size] = (PyTupleObject *) op->ob_item[0];
+ state->numfree[size]--;
/* Inline PyObject_InitVar */
#ifdef Py_TRACE_REFS
Py_SET_SIZE(op, size);
@@ -107,13 +85,15 @@
{
PyTupleObject *op;
#if PyTuple_MAXSAVESIZE > 0
- if (size == 0 && free_list[0]) {
- op = free_list[0];
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
+ if (size == 0 && state->free_list[0]) {
+ op = state->free_list[0];
Py_INCREF(op);
return (PyObject *) op;
}
#endif
- op = tuple_alloc(size);
+ op = tuple_alloc(state, size);
if (op == NULL) {
return NULL;
}
@@ -122,8 +102,8 @@
}
#if PyTuple_MAXSAVESIZE > 0
if (size == 0) {
- free_list[0] = op;
- ++numfree[0];
+ state->free_list[0] = op;
+ ++state->numfree[0];
Py_INCREF(op); /* extra INCREF so that this is never freed */
}
#endif
@@ -210,8 +190,11 @@
return PyTuple_New(0);
}
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
+
va_start(vargs, n);
- PyTupleObject *result = tuple_alloc(n);
+ PyTupleObject *result = tuple_alloc(state, n);
if (result == NULL) {
va_end(vargs);
return NULL;
@@ -233,22 +216,24 @@
static void
tupledealloc(PyTupleObject *op)
{
- Py_ssize_t i;
Py_ssize_t len = Py_SIZE(op);
PyObject_GC_UnTrack(op);
Py_TRASHCAN_BEGIN(op, tupledealloc)
if (len > 0) {
- i = len;
- while (--i >= 0)
+ Py_ssize_t i = len;
+ while (--i >= 0) {
Py_XDECREF(op->ob_item[i]);
+ }
#if PyTuple_MAXSAVESIZE > 0
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
if (len < PyTuple_MAXSAVESIZE &&
- numfree[len] < PyTuple_MAXFREELIST &&
+ state->numfree[len] < PyTuple_MAXFREELIST &&
Py_IS_TYPE(op, &PyTuple_Type))
{
- op->ob_item[0] = (PyObject *) free_list[len];
- numfree[len]++;
- free_list[len] = op;
+ op->ob_item[0] = (PyObject *) state->free_list[len];
+ state->numfree[len]++;
+ state->free_list[len] = op;
goto done; /* return */
}
#endif
@@ -423,7 +408,9 @@
return PyTuple_New(0);
}
- PyTupleObject *tuple = tuple_alloc(n);
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
+ PyTupleObject *tuple = tuple_alloc(state, n);
if (tuple == NULL) {
return NULL;
}
@@ -481,7 +468,8 @@
Py_TYPE(bb)->tp_name);
return NULL;
}
-#define b ((PyTupleObject *)bb)
+ PyTupleObject *b = (PyTupleObject *)bb;
+
if (Py_SIZE(b) == 0 && PyTuple_CheckExact(a)) {
Py_INCREF(a);
return (PyObject *)a;
@@ -492,7 +480,9 @@
return PyTuple_New(0);
}
- np = tuple_alloc(size);
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
+ np = tuple_alloc(state, size);
if (np == NULL) {
return NULL;
}
@@ -512,7 +502,6 @@
}
tuple_gc_track(np);
return (PyObject *)np;
-#undef b
}
static PyObject *
@@ -536,7 +525,9 @@
if (n > PY_SSIZE_T_MAX / Py_SIZE(a))
return PyErr_NoMemory();
size = Py_SIZE(a) * n;
- np = tuple_alloc(size);
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
+ np = tuple_alloc(state, size);
if (np == NULL)
return NULL;
p = np->ob_item;
@@ -801,7 +792,9 @@
return (PyObject *)self;
}
else {
- PyTupleObject* result = tuple_alloc(slicelength);
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_tuple_state *state = &interp->tuple;
+ PyTupleObject* result = tuple_alloc(state, slicelength);
if (!result) return NULL;
src = self->ob_item;
@@ -963,13 +956,14 @@
}
void
-_PyTuple_ClearFreeList(void)
+_PyTuple_ClearFreeList(PyThreadState *tstate)
{
#if PyTuple_MAXSAVESIZE > 0
+ struct _Py_tuple_state *state = &tstate->interp->tuple;
for (Py_ssize_t i = 1; i < PyTuple_MAXSAVESIZE; i++) {
- PyTupleObject *p = free_list[i];
- free_list[i] = NULL;
- numfree[i] = 0;
+ PyTupleObject *p = state->free_list[i];
+ state->free_list[i] = NULL;
+ state->numfree[i] = 0;
while (p) {
PyTupleObject *q = p;
p = (PyTupleObject *)(p->ob_item[0]);
@@ -981,14 +975,15 @@
}
void
-_PyTuple_Fini(void)
+_PyTuple_Fini(PyThreadState *tstate)
{
#if PyTuple_MAXSAVESIZE > 0
+ struct _Py_tuple_state *state = &tstate->interp->tuple;
/* empty tuples are used all over the place and applications may
* rely on the fact that an empty tuple is a singleton. */
- Py_CLEAR(free_list[0]);
+ Py_CLEAR(state->free_list[0]);
- _PyTuple_ClearFreeList();
+ _PyTuple_ClearFreeList(tstate);
#endif
}