[Python-checkins] bpo-40521: Make dict free lists per-interpreter (GH-20645)

Victor Stinner webhook-mailer at python.org
Tue Jun 23 05:33:34 EDT 2020

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https://github.com/python/cpython/commit/b4e85cadfbc2b1b24ec5f3159e351dbacedaa5e0
commit: b4e85cadfbc2b1b24ec5f3159e351dbacedaa5e0
branch: master
author: Victor Stinner <vstinner at python.org>
committer: GitHub <noreply at github.com>
date: 2020年06月23日T11:33:18+02:00
summary:
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".
files:
M Include/internal/pycore_gc.h
M Include/internal/pycore_interp.h
M Include/internal/pycore_pylifecycle.h
M Misc/NEWS.d/next/Core and Builtins/2020-05-20-01-17-34.bpo-40521.wvAehI.rst
M Modules/gcmodule.c
M Objects/dictobject.c
M Python/pylifecycle.c
diff --git a/Include/internal/pycore_gc.h b/Include/internal/pycore_gc.h
index fd3fb7f94cab0..da202a1df532e 100644
--- a/Include/internal/pycore_gc.h
+++ b/Include/internal/pycore_gc.h
@@ -169,7 +169,7 @@ extern void _PyFrame_ClearFreeList(PyThreadState *tstate);
 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 981b73340b7ea..3f64edcee983b 100644
--- a/Include/internal/pycore_interp.h
+++ b/Include/internal/pycore_interp.h
@@ -69,6 +69,14 @@ struct _Py_unicode_state {
 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 @@ struct _Py_list_state {
 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 @@ struct _Py_context_state {
 };
 
 
-
 /* interpreter state */
 
 #define _PY_NSMALLPOSINTS 257
@@ -182,8 +193,6 @@ struct _is {
 PyObject *codec_error_registry;
 int codecs_initialized;
 
- struct _Py_unicode_state unicode;
-
 PyConfig config;
 #ifdef HAVE_DLOPEN
 int dlopenflags;
@@ -224,16 +233,18 @@ struct _is {
 */
 PyLongObject* small_ints[_PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS];
 #endif
+ struct _Py_unicode_state unicode;
+ 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;
+
 struct _Py_tuple_state tuple;
 struct _Py_list_state list;
- struct _Py_float_state float_state;
+ struct _Py_dict_state dict_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;
 };
 
 /* Used by _PyImport_Cleanup() */
diff --git a/Include/internal/pycore_pylifecycle.h b/Include/internal/pycore_pylifecycle.h
index 3e3657339a4a4..dc99737829772 100644
--- a/Include/internal/pycore_pylifecycle.h
+++ b/Include/internal/pycore_pylifecycle.h
@@ -59,7 +59,7 @@ extern PyStatus _PyGC_Init(PyThreadState *tstate);
 /* 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 39cb80447f6a9..3406ca8c973d8 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 110a48d8cd76f..8833400caba75 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -1038,7 +1038,7 @@ clear_freelists(PyThreadState *tstate)
 _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 55bf4aefbbeac..f3b1157177655 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -247,58 +247,47 @@ static uint64_t pydict_global_version = 0;
 
 #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]);
 }
-#endif
 }
 
-/* Print summary info about the state of the optimized allocator */
+
 void
-_PyDict_DebugMallocStats(FILE *out)
+_PyDict_Fini(PyThreadState *tstate)
 {
-#if PyDict_MAXFREELIST > 0
- _PyDebugAllocatorStats(out,
- "free PyDictObject", numfree, sizeof(PyDictObject));
+ _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_Fini(void)
+_PyDict_DebugMallocStats(FILE *out)
 {
- _PyDict_ClearFreeList();
+ PyInterpreterState *interp = _PyInterpreterState_GET();
+ struct _Py_dict_state *state = &interp->dict_state;
+ _PyDebugAllocatorStats(out, "free PyDictObject",
+ state->numfree, sizeof(PyDictObject));
 }
 
+
 #define DK_SIZE(dk) ((dk)->dk_size)
 #if SIZEOF_VOID_P > 4
 #define DK_IXSIZE(dk) \
@@ -543,7 +532,8 @@ _PyDict_CheckConsistency(PyObject *op, int check_content)
 }
 
 
-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 @@ static PyDictKeysObject *new_keys_object(Py_ssize_t size)
 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 @@ free_keys_object(PyDictKeysObject *keys)
 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 @@ new_dict(PyDictKeysObject *keys, PyObject **values)
 {
 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 @@ dictresize(PyDictObject *mp, Py_ssize_t minsize)
 #ifdef Py_REF_DEBUG
 _Py_RefTotal--;
 #endif
-#if PyDict_MAXFREELIST > 0
+ 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 &&
- numfreekeys < PyDict_MAXFREELIST)
+ state->keys_numfree < PyDict_MAXFREELIST)
 {
- keys_free_list[numfreekeys++] = oldkeys;
+ state->keys_free_list[state->keys_numfree++] = oldkeys;
 }
- else
-#endif
- {
+ else {
 PyObject_FREE(oldkeys);
 }
 }
@@ -2028,13 +2032,16 @@ dict_dealloc(PyDictObject *mp)
 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 87f25e623f570..1b4a3db517c1d 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1258,9 +1258,7 @@ finalize_interp_types(PyThreadState *tstate, int is_main_interp)
 if (is_main_interp) {
 _PySet_Fini();
 }
- if (is_main_interp) {
- _PyDict_Fini();
- }
+ _PyDict_Fini(tstate);
 _PyList_Fini(tstate);
 _PyTuple_Fini(tstate);
 

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