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bpo-46006: Move the interned strings and identifiers to _PyRuntimeState. #30131

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bpo-46006: Move the interned strings and identifiers to _PyRuntimeState. #30131

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e79afd9
Move the unicode identifiers (_Py_Identifer) to _PyRuntimeState.
ericsnowcurrently Dec 16, 2021
7c6c441
Move the interned strings to _PyRuntimeState.
ericsnowcurrently Dec 16, 2021
58d9c0b
Only clean up it it's the main interpreter.
ericsnowcurrently Dec 17, 2021
01f19dc
Add a NEWS entry.
ericsnowcurrently Dec 17, 2021
b60bd33
Only expect NULL if the main interpreter.
ericsnowcurrently Dec 17, 2021
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Move the unicode identifiers (_Py_Identifer) to _PyRuntimeState.
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@ericsnowcurrently
ericsnowcurrently committed Dec 16, 2021
commit e79afd9acda243ecbc6927a2d233cef8e9ffc164
11 changes: 11 additions & 0 deletions Include/internal/pycore_global_objects.h
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Expand Up @@ -54,6 +54,17 @@ struct _Py_global_objects {
* -_PY_NSMALLNEGINTS (inclusive) to _PY_NSMALLPOSINTS (exclusive).
*/
PyLongObject small_ints[_PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS];

/* Unicode identifiers (_Py_Identifier): see _PyUnicode_FromId() */
struct _Py_unicode_ids {
PyThread_type_lock lock;
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Isn't this lock unnecessary? The GIL is held whenever an identifier is used, isn't it?

// next_index value must be preserved when Py_Initialize()/Py_Finalize()
// is called multiple times: see _PyUnicode_FromId() implementation.
Py_ssize_t next_index;

Py_ssize_t size;
PyObject **array;
} unicode_ids;
} singletons;
};

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2 changes: 0 additions & 2 deletions Include/internal/pycore_runtime.h
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Expand Up @@ -116,8 +116,6 @@ typedef struct pyruntimestate {
void *open_code_userdata;
_Py_AuditHookEntry *audit_hook_head;

struct _Py_unicode_runtime_ids unicode_ids;

struct _Py_global_objects global_objects;
// If anything gets added after global_objects then
// _PyRuntimeState_reset() needs to get updated to clear it.
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15 changes: 0 additions & 15 deletions Include/internal/pycore_unicodeobject.h
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Expand Up @@ -19,13 +19,6 @@ extern void _PyUnicode_Fini(PyInterpreterState *);

/* other API */

struct _Py_unicode_runtime_ids {
PyThread_type_lock lock;
// next_index value must be preserved when Py_Initialize()/Py_Finalize()
// is called multiple times: see _PyUnicode_FromId() implementation.
Py_ssize_t next_index;
};

/* fs_codec.encoding is initialized to NULL.
Later, it is set to a non-NULL string by _PyUnicode_InitEncodings(). */
struct _Py_unicode_fs_codec {
Expand All @@ -35,11 +28,6 @@ struct _Py_unicode_fs_codec {
_Py_error_handler error_handler;
};

struct _Py_unicode_ids {
Py_ssize_t size;
PyObject **array;
};

struct _Py_unicode_state {
// The empty Unicode object is a singleton to improve performance.
PyObject *empty_string;
Expand All @@ -57,9 +45,6 @@ struct _Py_unicode_state {
count of a string is: s->ob_refcnt + (s->state ? 2 : 0)
*/
PyObject *interned;

// Unicode identifiers (_Py_Identifier): see _PyUnicode_FromId()
struct _Py_unicode_ids ids;
};

extern void _PyUnicode_ClearInterned(PyInterpreterState *);
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50 changes: 23 additions & 27 deletions Objects/unicodeobject.c
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Expand Up @@ -233,6 +233,8 @@ static int unicode_is_singleton(PyObject *unicode);
#endif


#define IDENTIFIERS _Py_SINGLETON(unicode_ids)
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Can you drop the IDENTIFIERS and INTERNED macros. They impair readability.
You can leave _Py_SINGLETON as it conveys some meaning.


static struct _Py_unicode_state*
get_unicode_state(void)
{
Expand Down Expand Up @@ -2331,30 +2333,25 @@ PyUnicode_FromString(const char *u)
PyObject *
_PyUnicode_FromId(_Py_Identifier *id)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
struct _Py_unicode_ids *ids = &interp->unicode.ids;

Py_ssize_t index = _Py_atomic_size_get(&id->index);
if (index < 0) {
struct _Py_unicode_runtime_ids *rt_ids = &interp->runtime->unicode_ids;

PyThread_acquire_lock(rt_ids->lock, WAIT_LOCK);
PyThread_acquire_lock(IDENTIFIERS.lock, WAIT_LOCK);
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Drop this, and assert that the GIL is held?

// Check again to detect concurrent access. Another thread can have
// initialized the index while this thread waited for the lock.
index = _Py_atomic_size_get(&id->index);
if (index < 0) {
assert(rt_ids->next_index < PY_SSIZE_T_MAX);
index = rt_ids->next_index;
rt_ids->next_index++;
assert(IDENTIFIERS.next_index < PY_SSIZE_T_MAX);
index = IDENTIFIERS.next_index;
IDENTIFIERS.next_index++;
_Py_atomic_size_set(&id->index, index);
}
PyThread_release_lock(rt_ids->lock);
PyThread_release_lock(IDENTIFIERS.lock);
}
assert(index >= 0);

PyObject *obj;
if (index < ids->size) {
obj = ids->array[index];
if (index < IDENTIFIERS.size) {
obj = IDENTIFIERS.array[index];
if (obj) {
// Return a borrowed reference
return obj;
Expand All @@ -2368,38 +2365,37 @@ _PyUnicode_FromId(_Py_Identifier *id)
}
PyUnicode_InternInPlace(&obj);

if (index >= ids->size) {
if (index >= IDENTIFIERS.size) {
// Overallocate to reduce the number of realloc
Py_ssize_t new_size = Py_MAX(index * 2, 16);
Py_ssize_t item_size = sizeof(ids->array[0]);
PyObject **new_array = PyMem_Realloc(ids->array, new_size * item_size);
Py_ssize_t item_size = sizeof(IDENTIFIERS.array[0]);
PyObject **new_array = PyMem_Realloc(IDENTIFIERS.array, new_size * item_size);
if (new_array == NULL) {
PyErr_NoMemory();
return NULL;
}
memset(&new_array[ids->size], 0, (new_size - ids->size) * item_size);
ids->array = new_array;
ids->size = new_size;
memset(&new_array[IDENTIFIERS.size], 0, (new_size - IDENTIFIERS.size) * item_size);
IDENTIFIERS.array = new_array;
IDENTIFIERS.size = new_size;
}

// The array stores a strong reference
ids->array[index] = obj;
IDENTIFIERS.array[index] = obj;

// Return a borrowed reference
return obj;
}


static void
unicode_clear_identifiers(struct _Py_unicode_state *state)
unicode_clear_identifiers(void)
{
struct _Py_unicode_ids *ids = &state->ids;
for (Py_ssize_t i=0; i < ids->size; i++) {
Py_XDECREF(ids->array[i]);
for (Py_ssize_t i=0; i < IDENTIFIERS.size; i++) {
Py_XDECREF(IDENTIFIERS.array[i]);
}
ids->size = 0;
PyMem_Free(ids->array);
ids->array = NULL;
IDENTIFIERS.size = 0;
PyMem_Free(IDENTIFIERS.array);
IDENTIFIERS.array = NULL;
// Don't reset _PyRuntime next_index: _Py_Identifier.id remains valid
// after Py_Finalize().
}
Expand Down Expand Up @@ -16095,7 +16091,7 @@ _PyUnicode_Fini(PyInterpreterState *interp)

_PyUnicode_FiniEncodings(&state->fs_codec);

unicode_clear_identifiers(state);
unicode_clear_identifiers();

for (Py_ssize_t i = 0; i < 256; i++) {
Py_CLEAR(state->latin1[i]);
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14 changes: 9 additions & 5 deletions Python/pystate.c
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Expand Up @@ -120,8 +120,9 @@ init_runtime(_PyRuntimeState *runtime,
// Set it to the ID of the main thread of the main interpreter.
runtime->main_thread = PyThread_get_thread_ident();

runtime->unicode_ids.next_index = unicode_next_index;
runtime->unicode_ids.lock = unicode_ids_mutex;
struct _Py_unicode_ids *ids = &runtime->global_objects.singletons.unicode_ids;
ids->next_index = unicode_next_index;
ids->lock = unicode_ids_mutex;

runtime->_initialized = 1;
}
Expand All @@ -137,7 +138,8 @@ _PyRuntimeState_Init(_PyRuntimeState *runtime)
_Py_AuditHookEntry *audit_hook_head = runtime->audit_hook_head;
// bpo-42882: Preserve next_index value if Py_Initialize()/Py_Finalize()
// is called multiple times.
Py_ssize_t unicode_next_index = runtime->unicode_ids.next_index;
struct _Py_unicode_ids *ids = &runtime->global_objects.singletons.unicode_ids;
Py_ssize_t unicode_next_index = ids->next_index;

PyThread_type_lock lock1, lock2, lock3;
if (alloc_for_runtime(&lock1, &lock2, &lock3) != 0) {
Expand All @@ -164,7 +166,8 @@ _PyRuntimeState_Fini(_PyRuntimeState *runtime)

FREE_LOCK(runtime->interpreters.mutex);
FREE_LOCK(runtime->xidregistry.mutex);
FREE_LOCK(runtime->unicode_ids.lock);
struct _Py_unicode_ids *ids = &runtime->global_objects.singletons.unicode_ids;
FREE_LOCK(ids->lock);

#undef FREE_LOCK
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
Expand All @@ -186,7 +189,8 @@ _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime)

int reinit_interp = _PyThread_at_fork_reinit(&runtime->interpreters.mutex);
int reinit_xidregistry = _PyThread_at_fork_reinit(&runtime->xidregistry.mutex);
int reinit_unicode_ids = _PyThread_at_fork_reinit(&runtime->unicode_ids.lock);
struct _Py_unicode_ids *ids = &runtime->global_objects.singletons.unicode_ids;
int reinit_unicode_ids = _PyThread_at_fork_reinit(&ids->lock);

PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);

Expand Down
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