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.
diff --git a/Include/internal/pycore_gc.h b/Include/internal/pycore_gc.h
index 01265d3..3388b4d 100644
--- a/Include/internal/pycore_gc.h
+++ b/Include/internal/pycore_gc.h
@@ -168,7 +168,7 @@
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);
diff --git a/Include/internal/pycore_interp.h b/Include/internal/pycore_interp.h
index 9b805f0..0eab246 100644
--- a/Include/internal/pycore_interp.h
+++ b/Include/internal/pycore_interp.h
@@ -84,6 +84,16 @@
#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 @@
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;
diff --git a/Include/internal/pycore_pylifecycle.h b/Include/internal/pycore_pylifecycle.h
index 06d2ac1..3c35ca2 100644
--- a/Include/internal/pycore_pylifecycle.h
+++ b/Include/internal/pycore_pylifecycle.h
@@ -61,7 +61,7 @@
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);
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst b/Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst
index 71a1064..54cc600 100644
--- a/Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst
@@ -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.
diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index 45dc89d..2f062d0 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -1029,7 +1029,7 @@
_PyFrame_ClearFreeList(tstate);
_PyTuple_ClearFreeList(tstate);
_PyFloat_ClearFreeList(tstate);
- _PyList_ClearFreeList();
+ _PyList_ClearFreeList(tstate);
_PyDict_ClearFreeList();
_PyAsyncGen_ClearFreeLists();
_PyContext_ClearFreeList();
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 30d2620..043256d 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -96,65 +96,59 @@
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 @@
}
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
}
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 1dbdbfd..09d4d88 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1251,8 +1251,8 @@
{
_PyFrame_Fini(tstate);
_PyTuple_Fini(tstate);
+ _PyList_Fini(tstate);
if (is_main_interp) {
- _PyList_Fini();
_PySet_Fini();
_PyBytes_Fini();
}
@@ -1296,6 +1296,8 @@
_PyGC_CollectNoFail();
}
+ _PyGC_Fini(tstate);
+
finalize_interp_types(tstate, is_main_interp);
if (is_main_interp) {
@@ -1309,8 +1311,6 @@
_PyExc_Fini();
}
-
- _PyGC_Fini(tstate);
}