bpo-40521: Make dict free lists per-interpreter (GH-20645)
Each interpreter now has its own dict free list:
* Move dict free lists into PyInterpreterState.
* Move PyDict_MAXFREELIST define to pycore_interp.h
* Add _Py_dict_state structure.
* Add tstate parameter to _PyDict_ClearFreeList() and _PyDict_Fini().
* In debug mode, ensure that the dict free lists are not used after
_PyDict_Fini() is called.
* Remove "#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS".
diff --git a/Include/internal/pycore_gc.h b/Include/internal/pycore_gc.h
index fd3fb7f..da202a1 100644
--- a/Include/internal/pycore_gc.h
+++ b/Include/internal/pycore_gc.h
@@ -169,7 +169,7 @@
extern void _PyTuple_ClearFreeList(PyThreadState *tstate);
extern void _PyFloat_ClearFreeList(PyThreadState *tstate);
extern void _PyList_ClearFreeList(PyThreadState *tstate);
-extern void _PyDict_ClearFreeList(void);
+extern void _PyDict_ClearFreeList(PyThreadState *tstate);
extern void _PyAsyncGen_ClearFreeLists(PyThreadState *tstate);
extern void _PyContext_ClearFreeList(PyThreadState *tstate);
diff --git a/Include/internal/pycore_interp.h b/Include/internal/pycore_interp.h
index 981b733..3f64edc 100644
--- a/Include/internal/pycore_interp.h
+++ b/Include/internal/pycore_interp.h
@@ -69,6 +69,14 @@
struct _Py_unicode_fs_codec fs_codec;
};
+struct _Py_float_state {
+ /* Special free list
+ free_list is a singly-linked list of available PyFloatObjects,
+ linked via abuse of their ob_type members. */
+ int numfree;
+ PyFloatObject *free_list;
+};
+
/* Speed optimization to avoid frequent malloc/free of small tuples */
#ifndef PyTuple_MAXSAVESIZE
// Largest tuple to save on free list
@@ -99,12 +107,16 @@
int numfree;
};
-struct _Py_float_state {
- /* Special free list
- free_list is a singly-linked list of available PyFloatObjects,
- linked via abuse of their ob_type members. */
+#ifndef PyDict_MAXFREELIST
+# define PyDict_MAXFREELIST 80
+#endif
+
+struct _Py_dict_state {
+ /* Dictionary reuse scheme to save calls to malloc and free */
+ PyDictObject *free_list[PyDict_MAXFREELIST];
int numfree;
- PyFloatObject *free_list;
+ PyDictKeysObject *keys_free_list[PyDict_MAXFREELIST];
+ int keys_numfree;
};
struct _Py_frame_state {
@@ -136,7 +148,6 @@
};
-
/* interpreter state */
#define _PY_NSMALLPOSINTS 257
@@ -182,8 +193,6 @@
PyObject *codec_error_registry;
int codecs_initialized;
- struct _Py_unicode_state unicode;
-
PyConfig config;
#ifdef HAVE_DLOPEN
int dlopenflags;
@@ -224,16 +233,18 @@
*/
PyLongObject* small_ints[_PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS];
#endif
- struct _Py_tuple_state tuple;
- struct _Py_list_state list;
+ struct _Py_unicode_state unicode;
struct _Py_float_state float_state;
- struct _Py_frame_state frame;
- struct _Py_async_gen_state async_gen;
- struct _Py_context_state context;
-
/* Using a cache is very effective since typically only a single slice is
created and then deleted again. */
PySliceObject *slice_cache;
+
+ struct _Py_tuple_state tuple;
+ struct _Py_list_state list;
+ struct _Py_dict_state dict_state;
+ struct _Py_frame_state frame;
+ struct _Py_async_gen_state async_gen;
+ struct _Py_context_state context;
};
/* Used by _PyImport_Cleanup() */
diff --git a/Include/internal/pycore_pylifecycle.h b/Include/internal/pycore_pylifecycle.h
index 3e36573..dc99737 100644
--- a/Include/internal/pycore_pylifecycle.h
+++ b/Include/internal/pycore_pylifecycle.h
@@ -59,7 +59,7 @@
/* Various internal finalizers */
extern void _PyFrame_Fini(PyThreadState *tstate);
-extern void _PyDict_Fini(void);
+extern void _PyDict_Fini(PyThreadState *tstate);
extern void _PyTuple_Fini(PyThreadState *tstate);
extern void _PyList_Fini(PyThreadState *tstate);
extern void _PySet_Fini(void);
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 39cb804..3406ca8 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
@@ -1,4 +1,5 @@
The tuple free lists, the empty tuple singleton, the list free list, the float
-free list, the slice cache, the frame free list, the asynchronous generator
-free lists, and the context free list are no longer shared by all interpreters:
-each interpreter now its has own free lists and caches.
+free list, the slice cache, the dict free lists, the frame free list, the
+asynchronous generator free lists, and the context 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 110a48d..8833400 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -1038,7 +1038,7 @@
_PyTuple_ClearFreeList(tstate);
_PyFloat_ClearFreeList(tstate);
_PyList_ClearFreeList(tstate);
- _PyDict_ClearFreeList();
+ _PyDict_ClearFreeList(tstate);
_PyAsyncGen_ClearFreeLists(tstate);
_PyContext_ClearFreeList(tstate);
}
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 55bf4ae..f3b1157 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -247,58 +247,47 @@
#define DICT_NEXT_VERSION() (++pydict_global_version)
-/* Dictionary reuse scheme to save calls to malloc and free */
-#ifndef PyDict_MAXFREELIST
-#define PyDict_MAXFREELIST 80
-#endif
-
-/* bpo-40521: dict free lists are shared by all interpreters. */
-#ifdef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-# undef PyDict_MAXFREELIST
-# define PyDict_MAXFREELIST 0
-#endif
-
-#if PyDict_MAXFREELIST > 0
-static PyDictObject *free_list[PyDict_MAXFREELIST];
-static int numfree = 0;
-static PyDictKeysObject *keys_free_list[PyDict_MAXFREELIST];
-static int numfreekeys = 0;
-#endif
-
#include "clinic/dictobject.c.h"
void
-_PyDict_ClearFreeList(void)
+_PyDict_ClearFreeList(PyThreadState *tstate)
{
-#if PyDict_MAXFREELIST > 0
- while (numfree) {
- PyDictObject *op = free_list[--numfree];
+ struct _Py_dict_state *state = &tstate->interp->dict_state;
+ while (state->numfree) {
+ PyDictObject *op = state->free_list[--state->numfree];
assert(PyDict_CheckExact(op));
PyObject_GC_Del(op);
}
- while (numfreekeys) {
- PyObject_FREE(keys_free_list[--numfreekeys]);
+ while (state->keys_numfree) {
+ PyObject_FREE(state->keys_free_list[--state->keys_numfree]);
}
+}
+
+
+void
+_PyDict_Fini(PyThreadState *tstate)
+{
+ _PyDict_ClearFreeList(tstate);
+#ifdef Py_DEBUG
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+ state->numfree = -1;
+ state->keys_numfree = -1;
#endif
}
+
/* Print summary info about the state of the optimized allocator */
void
_PyDict_DebugMallocStats(FILE *out)
{
-#if PyDict_MAXFREELIST > 0
- _PyDebugAllocatorStats(out,
- "free PyDictObject", numfree, sizeof(PyDictObject));
-#endif
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+ _PyDebugAllocatorStats(out, "free PyDictObject",
+ state->numfree, sizeof(PyDictObject));
}
-void
-_PyDict_Fini(void)
-{
- _PyDict_ClearFreeList();
-}
-
#define DK_SIZE(dk) ((dk)->dk_size)
#if SIZEOF_VOID_P > 4
#define DK_IXSIZE(dk) \
@@ -543,7 +532,8 @@
}
-static PyDictKeysObject *new_keys_object(Py_ssize_t size)
+static PyDictKeysObject*
+new_keys_object(Py_ssize_t size)
{
PyDictKeysObject *dk;
Py_ssize_t es, usable;
@@ -567,12 +557,16 @@
es = sizeof(Py_ssize_t);
}
-#if PyDict_MAXFREELIST > 0
- if (size == PyDict_MINSIZE && numfreekeys > 0) {
- dk = keys_free_list[--numfreekeys];
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+#ifdef Py_DEBUG
+ // new_keys_object() must not be called after _PyDict_Fini()
+ assert(state->keys_numfree != -1);
+#endif
+ if (size == PyDict_MINSIZE && state->keys_numfree > 0) {
+ dk = state->keys_free_list[--state->keys_numfree];
}
else
-#endif
{
dk = PyObject_MALLOC(sizeof(PyDictKeysObject)
+ es * size
@@ -604,12 +598,16 @@
Py_XDECREF(entries[i].me_key);
Py_XDECREF(entries[i].me_value);
}
-#if PyDict_MAXFREELIST > 0
- if (keys->dk_size == PyDict_MINSIZE && numfreekeys < PyDict_MAXFREELIST) {
- keys_free_list[numfreekeys++] = keys;
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+#ifdef Py_DEBUG
+ // free_keys_object() must not be called after _PyDict_Fini()
+ assert(state->keys_numfree != -1);
+#endif
+ if (keys->dk_size == PyDict_MINSIZE && state->keys_numfree < PyDict_MAXFREELIST) {
+ state->keys_free_list[state->keys_numfree++] = keys;
return;
}
-#endif
PyObject_FREE(keys);
}
@@ -622,16 +620,19 @@
{
PyDictObject *mp;
assert(keys != NULL);
-#if PyDict_MAXFREELIST > 0
- if (numfree) {
- mp = free_list[--numfree];
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+#ifdef Py_DEBUG
+ // new_dict() must not be called after _PyDict_Fini()
+ assert(state->numfree != -1);
+#endif
+ if (state->numfree) {
+ mp = state->free_list[--state->numfree];
assert (mp != NULL);
assert (Py_IS_TYPE(mp, &PyDict_Type));
_Py_NewReference((PyObject *)mp);
}
- else
-#endif
- {
+ else {
mp = PyObject_GC_New(PyDictObject, &PyDict_Type);
if (mp == NULL) {
dictkeys_decref(keys);
@@ -1280,15 +1281,18 @@
#ifdef Py_REF_DEBUG
_Py_RefTotal--;
#endif
-#if PyDict_MAXFREELIST > 0
- if (oldkeys->dk_size == PyDict_MINSIZE &&
- numfreekeys < PyDict_MAXFREELIST)
- {
- keys_free_list[numfreekeys++] = oldkeys;
- }
- else
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+#ifdef Py_DEBUG
+ // dictresize() must not be called after _PyDict_Fini()
+ assert(state->keys_numfree != -1);
#endif
+ if (oldkeys->dk_size == PyDict_MINSIZE &&
+ state->keys_numfree < PyDict_MAXFREELIST)
{
+ state->keys_free_list[state->keys_numfree++] = oldkeys;
+ }
+ else {
PyObject_FREE(oldkeys);
}
}
@@ -2028,13 +2032,16 @@
assert(keys->dk_refcnt == 1);
dictkeys_decref(keys);
}
-#if PyDict_MAXFREELIST > 0
- if (numfree < PyDict_MAXFREELIST && Py_IS_TYPE(mp, &PyDict_Type)) {
- free_list[numfree++] = mp;
- }
- else
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+#ifdef Py_DEBUG
+ // new_dict() must not be called after _PyDict_Fini()
+ assert(state->numfree != -1);
#endif
- {
+ if (state->numfree < PyDict_MAXFREELIST && Py_IS_TYPE(mp, &PyDict_Type)) {
+ state->free_list[state->numfree++] = mp;
+ }
+ else {
Py_TYPE(mp)->tp_free((PyObject *)mp);
}
Py_TRASHCAN_END
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 87f25e6..1b4a3db 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1258,9 +1258,7 @@
if (is_main_interp) {
_PySet_Fini();
}
- if (is_main_interp) {
- _PyDict_Fini();
- }
+ _PyDict_Fini(tstate);
_PyList_Fini(tstate);
_PyTuple_Fini(tstate);