8000 gh-112075: Make instance attributes stored in inline "dict" thread safe by DinoV · Pull Request #114742 · python/cpython · GitHub
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gh-112075: Make instance attributes stored in inline "dict" thread safe #114742

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Merged
merged 8 commits into from
Apr 22, 2024
Merged

gh-112075: Make instance attributes stored in inline "dict" thread safe #114742

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048daa7
Make instance attributes stored in inline "dict" thread safe
DinoV Apr 2, 2024
322914f
Insert into dict on store if dict is materialized and other feedback
DinoV Apr 4, 2024
106685a
_PyObject_TryStoreInstanceAttribute -> _PyObject_StoreInstanceAttribute
DinoV Apr 15, 2024
11d450c
Cleanup _PyObject_SetManagedDict, use cst for inline valid flag, fix …
DinoV Apr 16, 2024
29968e0
Refactor del/set into set_or_del_lock_held, and avoid locking on newl…
DinoV Apr 17, 2024
0023395
Handle dict replacement case better
DinoV Apr 19, 2024
8433d25
Decref materialized dict on fail to set
DinoV Apr 19, 2024
ac503e8
Fix missing decref when storing and dict is detached but has been del…
DinoV Apr 19, 2024
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Insert into dict on store if dict is materialized and other feedback
  • Loading branch information
@DinoV
DinoV committed Apr 19, 2024
commit 322914f4cc10952c9ff5d39885349c49d1ee97c6
108 changes: 74 additions & 34 deletions Objects/dictobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6616,6 +6616,23 @@ make_dict_from_instance_attributes(PyInterpreterState *interp,
return res;
}

static PyDictObject *
materialize_managed_dict_lock_held(PyObject *obj)
{
_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(obj);

OBJECT_STAT_INC(dict_materialized_on_request);

PyDictValues *values = _PyObject_InlineValues(obj);
PyInterpreterState *interp = _PyInterpreterState_GET();
PyDictKeysObject *keys = CACHED_KEYS(Py_TYPE(obj));
OBJECT_STAT_INC(dict_materialized_on_request);
PyDictObject *dict = make_dict_from_instance_attributes(interp, keys, values);
FT_ATOMIC_STORE_PTR_RELEASE(_PyObject_ManagedDictPointer(obj)->dict,
(PyDictObject *)dict);
return dict;
}

PyDictObject *
_PyObject_MaterializeManagedDict(PyObject *obj)
{
Expand All @@ -6633,17 +6650,7 @@ _PyObject_MaterializeManagedDict(PyObject *obj)
goto exit;
}
#endif

OBJECT_STAT_INC(dict_materialized_on_request);

PyDictValues *values = _PyObject_InlineValues(obj);
PyInterpreterState *interp = _PyInterpreterState_GET();
PyDictKeysObject *keys = CACHED_KEYS(Py_TYPE(obj));
OBJECT_STAT_INC(dict_materialized_on_request);
dict = make_dict_from_instance_attributes(interp, keys, values);

FT_ATOMIC_STORE_PTR_RELEASE(_PyObject_ManagedDictPointer(obj)->dict,
(PyDictObject *)dict);
dict = materialize_managed_dict_lock_held(obj);

#ifdef Py_GIL_DISABLED
exit:
Expand All @@ -6652,8 +6659,9 @@ _PyObject_MaterializeManagedDict(PyObject *obj)
return dict;
}



// Called with either the object's lock or the dict's lock held
// depending on whether or not a dict has been materialized for
// the object.
static int
store_instance_attr_lock_held(PyObject *obj, PyDictValues *values,
PyObject *name, PyObject *value)
Expand Down 10000 Expand Up @@ -6703,14 +6711,38 @@ store_instance_attr_lock_held(PyObject *obj, PyDictValues *values,
}

if (ix == DKIX_EMPTY) {
int res;
if (dict == NULL) {
dict = _PyObject_MaterializeManagedDict(obj);
// Make the dict but don't publish it in the object
// so that no one else will see it.
dict = materialize_managed_dict_lock_held(obj);
if (dict == NULL) {
return -1;
}

if (value == NULL) {
res = PyDict_DelItem((PyObject *)dict, name);
} else {
res = PyDict_SetItem((PyObject *)dict, name, value);
}

return res;
}
// Caller needs to insert into materialized dict
return 1;

_Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(dict);

if (value == NULL) {
Py_hash_t hash;
if (!PyUnicode_CheckExact(name) || (hash = unicode_get_hash(name)) == -1) {
hash = PyObject_Hash(name);
if (hash == -1)
return -1;
}
res = delitem_knownhash_lock_held((PyObject *)dict, name, hash);
} else {
res = setitem_lock_held(dict, name, value);
}
return res;
}

PyObject *old_value = values->values[ix];
Expand Down Expand Up @@ -6742,12 +6774,32 @@ store_instance_attr_lock_held(PyObject *obj, PyDictValues *values,
return 0;
}

static inline int
store_instance_attr_dict(PyObject *obj, PyDictObject *dict, PyObject *name, PyObject *value)
{
PyDictValues *values = _PyObject_InlineValues(obj);
int res;
Py_BEGIN_CRITICAL_SECTION(dict);
if (dict->ma_values == values) {
res = store_instance_attr_lock_held(obj, values, name, value);
}
else {
if (value == NULL) {
res = PyDict_DelItem((PyObject *)dict, name);
} else {
res = PyDict_SetItem((PyObject *)dict, name, value);
}
}
Py_END_CRITICAL_SECTION();
return res;
}

int
_PyObject_TryStoreInstanceAttribute(PyObject *obj, PyObject *name, PyObject *value)
{
PyDictValues *values = _PyObject_InlineValues(obj);
if (!FT_ATOMIC_LOAD_UINT8_RELAXED(values->valid)) {
return 1;
return store_instance_attr_dict(obj, _PyObject_GetManagedDict(obj), name, value);
}

#ifdef Py_GIL_DISABLED
Expand All @@ -6764,7 +6816,6 @@ _PyObject_TryStoreInstanceAttribute(PyObject *obj, PyObject *name, PyObject *val
// prevent resizing.
PyDictObject *dict = _PyObject_GetManagedDict(obj);
if (dict == NULL) {
int retry_with_dict = 0;
Py_BEGIN_CRITICAL_SECTION(obj);
dict = _PyObject_GetManagedDict(obj);

Expand All @@ -6774,24 +6825,13 @@ _PyObject_TryStoreInstanceAttribute(PyObject *obj, PyObject *name, PyObject *val
else {
// We lost a race with the materialization of the dict, we'll
// try the insert with it...
retry_with_dict = 1;
}
Py_END_CRITICAL_SECTION();
if (retry_with_dict) {
goto with_dict;
}
Py_END_CRITICAL_SECTION();
}
else {
with_dict:
Py_BEGIN_CRITICAL_SECTION(dict);
if (dict->ma_values == values) {
res = store_instance_attr_lock_held(obj, values, name, value);
}
else {
// Caller needs to insert into dict
res = 1;
}
Py_END_CRITICAL_SECTION();
res = store_instance_attr_dict(obj, dict, name, value);
}
return res;
#else
Expand Down Expand Up @@ -6868,7 +6908,7 @@ _PyObject_TryGetInstanceAttribute(PyObject *obj, PyObject *name, PyObject **attr
if (dict == NULL) {
// Still no dict, we can read from the values
assert(values->valid);
value = _Py_atomic_load_ptr_relaxed(&values->values[ix]);
value = values->values[ix];
*attr = Py_XNewRef(value);
success = true;
}
Expand Down Expand Up @@ -7057,10 +7097,10 @@ _PyDict_DetachFromObject(PyDictObject *mp, PyObject *obj)
assert(mp->ma_values->embedded == 1);
assert(mp->ma_values->valid == 1);
assert(Py_TYPE(obj)->tp_flags & Py_TPFLAGS_INLINE_VALUES);
Py_BEGIN_CRITICAL_SECTION(mp);

mp->ma_values = copy_values(mp->ma_values);
_PyObject_InlineValues(obj)->valid = 0;
Py_END_CRITICAL_SECTION();

if (mp->ma_values == NULL) {
return -1;
}
Expand Down
4 changes: 1 addition & 3 deletions Objects/object.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1699,9 +1699,7 @@ _PyObject_GenericSetAttrWithDict(PyObject *obj, PyObject *name,

if ((tp->tp_flags & Py_TPFLAGS_INLINE_VALUES)) {
res = _PyObject_TryStoreInstanceAttribute(obj, name, value);
if (res <= 0) {
goto error_check;
}
goto error_check;
}

if ((tp->tp_flags & Py_TPFLAGS_MANAGED_DICT)) {
Expand Down
0