bpo-40521: Make list free list per-interpreter (GH-20642)

Each interpreter now has its own list free list:

* Move list numfree and free_list into PyInterpreterState.
* Add _Py_list_state structure.
* Add tstate parameter to _PyList_ClearFreeList()
  and _PyList_Fini().
* Remove "#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS".
* _PyGC_Fini() clears gcstate->garbage list which can be stored in
  the list free list. Call _PyGC_Fini() before _PyList_Fini() to
  prevent leaking this list.
This commit is contained in:
Victor Stinner 2020-06-05 02:05:41 +02:00 committed by GitHub
parent 052d3fc090
commit 88ec919010
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 51 additions and 42 deletions

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@ -168,7 +168,7 @@ PyAPI_FUNC(void) _PyGC_InitState(struct _gc_runtime_state *);
extern void _PyFrame_ClearFreeList(PyThreadState *tstate);
extern void _PyTuple_ClearFreeList(PyThreadState *tstate);
extern void _PyFloat_ClearFreeList(PyThreadState *tstate);
extern void _PyList_ClearFreeList(void);
extern void _PyList_ClearFreeList(PyThreadState *tstate);
extern void _PyDict_ClearFreeList(void);
extern void _PyAsyncGen_ClearFreeLists(void);
extern void _PyContext_ClearFreeList(void);

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@ -84,6 +84,16 @@ struct _Py_tuple_state {
#endif
};
/* Empty list reuse scheme to save calls to malloc and free */
#ifndef PyList_MAXFREELIST
# define PyList_MAXFREELIST 80
#endif
struct _Py_list_state {
PyListObject *free_list[PyList_MAXFREELIST];
int numfree;
};
struct _Py_float_state {
/* Special free list
free_list is a singly-linked list of available PyFloatObjects,
@ -192,6 +202,7 @@ struct _is {
PyLongObject* small_ints[_PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS];
#endif
struct _Py_tuple_state tuple;
struct _Py_list_state list;
struct _Py_float_state float_state;
struct _Py_frame_state frame;

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@ -61,7 +61,7 @@ extern PyStatus _PyGC_Init(PyThreadState *tstate);
extern void _PyFrame_Fini(PyThreadState *tstate);
extern void _PyDict_Fini(void);
extern void _PyTuple_Fini(PyThreadState *tstate);
extern void _PyList_Fini(void);
extern void _PyList_Fini(PyThreadState *tstate);
extern void _PySet_Fini(void);
extern void _PyBytes_Fini(void);
extern void _PyFloat_Fini(PyThreadState *tstate);

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@ -1,3 +1,3 @@
The tuple free lists, the empty tuple singleton, the float free list, the slice
cache, and the frame free list are no longer shared by all interpreters: each
interpreter now its has own free lists and caches.
The tuple free lists, the empty tuple singleton, the list free list, the float
free list, the slice cache, and the frame free list are no longer shared by all
interpreters: each interpreter now its has own free lists and caches.

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@ -1029,7 +1029,7 @@ clear_freelists(void)
_PyFrame_ClearFreeList(tstate);
_PyTuple_ClearFreeList(tstate);
_PyFloat_ClearFreeList(tstate);
_PyList_ClearFreeList();
_PyList_ClearFreeList(tstate);
_PyDict_ClearFreeList();
_PyAsyncGen_ClearFreeLists();
_PyContext_ClearFreeList();

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@ -96,65 +96,59 @@ list_preallocate_exact(PyListObject *self, Py_ssize_t size)
return 0;
}
/* Empty list reuse scheme to save calls to malloc and free */
#ifndef PyList_MAXFREELIST
# define PyList_MAXFREELIST 80
#endif
/* bpo-40521: list free lists are shared by all interpreters. */
#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
# undef PyList_MAXFREELIST
# define PyList_MAXFREELIST 0
#endif
static PyListObject *free_list[PyList_MAXFREELIST];
static int numfree = 0;
void
_PyList_ClearFreeList(void)
_PyList_ClearFreeList(PyThreadState *tstate)
{
while (numfree) {
PyListObject *op = free_list[--numfree];
struct _Py_list_state *state = &tstate->interp->list;
while (state->numfree) {
PyListObject *op = state->free_list[--state->numfree];
assert(PyList_CheckExact(op));
PyObject_GC_Del(op);
}
}
void
_PyList_Fini(void)
_PyList_Fini(PyThreadState *tstate)
{
_PyList_ClearFreeList();
_PyList_ClearFreeList(tstate);
}
/* Print summary info about the state of the optimized allocator */
void
_PyList_DebugMallocStats(FILE *out)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_list_state *state = &interp->list;
_PyDebugAllocatorStats(out,
"free PyListObject",
numfree, sizeof(PyListObject));
state->numfree, sizeof(PyListObject));
}
PyObject *
PyList_New(Py_ssize_t size)
{
PyListObject *op;
if (size < 0) {
PyErr_BadInternalCall();
return NULL;
}
if (numfree) {
numfree--;
op = free_list[numfree];
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_list_state *state = &interp->list;
PyListObject *op;
if (state->numfree) {
state->numfree--;
op = state->free_list[state->numfree];
_Py_NewReference((PyObject *)op);
} else {
op = PyObject_GC_New(PyListObject, &PyList_Type);
if (op == NULL)
return NULL;
}
if (size <= 0)
else {
op = PyObject_GC_New(PyListObject, &PyList_Type);
if (op == NULL) {
return NULL;
}
}
if (size <= 0) {
op->ob_item = NULL;
}
else {
op->ob_item = (PyObject **) PyMem_Calloc(size, sizeof(PyObject *));
if (op->ob_item == NULL) {
@ -334,10 +328,14 @@ list_dealloc(PyListObject *op)
}
PyMem_FREE(op->ob_item);
}
if (numfree < PyList_MAXFREELIST && PyList_CheckExact(op))
free_list[numfree++] = op;
else
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_list_state *state = &interp->list;
if (state->numfree < PyList_MAXFREELIST && PyList_CheckExact(op)) {
state->free_list[state->numfree++] = op;
}
else {
Py_TYPE(op)->tp_free((PyObject *)op);
}
Py_TRASHCAN_END
}

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@ -1251,8 +1251,8 @@ finalize_interp_types(PyThreadState *tstate, int is_main_interp)
{
_PyFrame_Fini(tstate);
_PyTuple_Fini(tstate);
_PyList_Fini(tstate);
if (is_main_interp) {
_PyList_Fini();
_PySet_Fini();
_PyBytes_Fini();
}
@ -1296,6 +1296,8 @@ finalize_interp_clear(PyThreadState *tstate)
_PyGC_CollectNoFail();
}
_PyGC_Fini(tstate);
finalize_interp_types(tstate, is_main_interp);
if (is_main_interp) {
@ -1309,8 +1311,6 @@ finalize_interp_clear(PyThreadState *tstate)
_PyExc_Fini();
}
_PyGC_Fini(tstate);
}