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https://github.com/python/cpython/commit/89e67ada6958cfd8d4eec221848f81b2619de099
commit: 89e67ada6958cfd8d4eec221848f81b2619de099
branch: main
author: Eric Snow <ericsnowcurrently@gmail.com>
committer: ericsnowcurrently <ericsnowcurrently@gmail.com>
date: 2023-03-27T16:53:05-06:00
summary:

gh-100227: Revert gh-102925 "gh-100227: Make the Global Interned Dict Safe for Isolated Interpreters" (gh-103063)

This reverts commit 87be8d9.

This approach to keeping the interned strings safe is turning out to be too complex for my taste (due to obmalloc isolation). For now I'm going with the simpler solution, making the dict per-interpreter. We can revisit that later if we want a sharing solution.

files:
M Include/internal/pycore_global_objects.h
M Include/internal/pycore_pystate.h
M Include/internal/pycore_runtime_init.h
M Include/internal/pycore_unicodeobject.h
M Objects/unicodeobject.c
M Python/pylifecycle.c
M Python/pystate.c

diff --git a/Include/internal/pycore_global_objects.h b/Include/internal/pycore_global_objects.h
index 858321d67df4..9957da1fc5f2 100644
--- a/Include/internal/pycore_global_objects.h
+++ b/Include/internal/pycore_global_objects.h
@@ -28,10 +28,6 @@ extern "C" {

struct _Py_cached_objects {
PyObject *interned_strings;
- /* A thread state tied to the main interpreter,
- used exclusively for when a global object (e.g. interned strings)
- is resized (i.e. deallocated + allocated) from an arbitrary thread. */
- PyThreadState main_tstate;
};

#define _Py_GLOBAL_OBJECT(NAME) \
diff --git a/Include/internal/pycore_pystate.h b/Include/internal/pycore_pystate.h
index f159b516e66b..7046ec8d9ada 100644
--- a/Include/internal/pycore_pystate.h
+++ b/Include/internal/pycore_pystate.h
@@ -127,11 +127,6 @@ PyAPI_FUNC(void) _PyThreadState_Init(
PyThreadState *tstate);
PyAPI_FUNC(void) _PyThreadState_DeleteExcept(PyThreadState *tstate);

-extern void _PyThreadState_InitDetached(PyThreadState *, PyInterpreterState *);
-extern void _PyThreadState_ClearDetached(PyThreadState *);
-
-extern PyObject * _Py_AddToGlobalDict(PyObject *, PyObject *, PyObject *);
-

static inline void
_PyThreadState_UpdateTracingState(PyThreadState *tstate)
diff --git a/Include/internal/pycore_runtime_init.h b/Include/internal/pycore_runtime_init.h
index fd358b2da6cc..7cfa7c0c0249 100644
--- a/Include/internal/pycore_runtime_init.h
+++ b/Include/internal/pycore_runtime_init.h
@@ -59,9 +59,6 @@ extern PyTypeObject _PyExc_MemoryError;
.types = { \
.next_version_tag = 1, \
}, \
- .cached_objects = { \
- .main_tstate = _PyThreadState_INIT, \
- }, \
.static_objects = { \
.singletons = { \
.small_ints = _Py_small_ints_INIT, \
diff --git a/Include/internal/pycore_unicodeobject.h b/Include/internal/pycore_unicodeobject.h
index ed4feb603d6f..19faceebf1d8 100644
--- a/Include/internal/pycore_unicodeobject.h
+++ b/Include/internal/pycore_unicodeobject.h
@@ -34,7 +34,6 @@ struct _Py_unicode_runtime_ids {

struct _Py_unicode_runtime_state {
struct _Py_unicode_runtime_ids ids;
- /* The interned dict is at _PyRuntime.cached_objects.interned_strings. */
};

/* fs_codec.encoding is initialized to NULL.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 891a65576ee2..b9fb53147b9b 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -14609,11 +14609,16 @@ PyUnicode_InternInPlace(PyObject **p)
}

PyObject *interned = get_interned_dict();
- PyObject *t = _Py_AddToGlobalDict(interned, s, s);
+ assert(interned != NULL);
+
+ PyObject *t = PyDict_SetDefault(interned, s, s);
+ if (t == NULL) {
+ PyErr_Clear();
+ return;
+ }
+
if (t != s) {
- if (t != NULL) {
- Py_SETREF(*p, Py_NewRef(t));
- }
+ Py_SETREF(*p, Py_NewRef(t));
return;
}

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 5d7f86218330..8110d94ba175 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -636,8 +636,6 @@ pycore_create_interpreter(_PyRuntimeState *runtime,
return status;
}

- _PyThreadState_InitDetached(&runtime->cached_objects.main_tstate, interp);
-
*tstate_p = tstate;
return _PyStatus_OK();
}
@@ -1934,8 +1932,6 @@ Py_FinalizeEx(void)
// XXX Do this sooner during finalization.
// XXX Ensure finalizer errors are handled properly.

- _PyThreadState_ClearDetached(&runtime->cached_objects.main_tstate);
-
finalize_interp_clear(tstate);
finalize_interp_delete(tstate->interp);

diff --git a/Python/pystate.c b/Python/pystate.c
index 394b12d24065..b17efdbefd12 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -565,124 +565,6 @@ _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime)
#endif


-//---------------
-// global objects
-//---------------
-
-/* The global objects thread state is meant to be used in a very limited
- way and should not be used to actually run any Python code. */
-
-static PyThreadState *
-bind_global_objects_state(_PyRuntimeState *runtime)
-{
- PyThreadState *main_tstate = &runtime->cached_objects.main_tstate;
-
- bind_tstate(main_tstate);
- /* Unlike _PyThreadState_Bind(), we do not modify gilstate TSS. */
-
- return main_tstate;
-}
-
-static void
-unbind_global_objects_state(_PyRuntimeState *runtime)
-{
- PyThreadState *main_tstate = &runtime->cached_objects.main_tstate;
- assert(tstate_is_alive(main_tstate));
- assert(!main_tstate->_status.active);
- assert(gilstate_tss_get(runtime) != main_tstate);
-
- unbind_tstate(main_tstate);
-
- /* This thread state may be bound/unbound repeatedly,
- so we must erase evidence that it was ever bound (or unbound). */
- main_tstate->_status.bound = 0;
- main_tstate->_status.unbound = 0;
-
- /* We must fully unlink the thread state from any OS thread,
- to allow it to be bound more than once. */
- main_tstate->thread_id = 0;
-#ifdef PY_HAVE_THREAD_NATIVE_ID
- main_tstate->native_thread_id = 0;
-#endif
-}
-
-static inline void
-acquire_global_objects_lock(_PyRuntimeState *runtime)
-{
- /* For now we can rely on the GIL, so we don't actually
- acquire a global lock here. */
- assert(current_fast_get(runtime) != NULL);
-}
-
-static inline void
-release_global_objects_lock(_PyRuntimeState *runtime)
-{
- /* For now we can rely on the GIL, so we don't actually
- release a global lock here. */
- assert(current_fast_get(runtime) != NULL);
-}
-
-PyObject *
-_Py_AddToGlobalDict(PyObject *dict, PyObject *key, PyObject *value)
-{
- assert(dict != NULL);
- assert(PyDict_CheckExact(dict));
-
- /* All global objects are stored in _PyRuntime
- and owned by the main interpreter. */
- _PyRuntimeState *runtime = &_PyRuntime;
- PyThreadState *curts = current_fast_get(runtime);
- PyInterpreterState *interp = curts->interp;
- assert(interp != NULL); // The GIL must be held.
-
- /* Due to interpreter isolation we must hold a global lock,
- starting at this point and ending before we return.
- Note that the operations in this function are very fucused
- and we should not expect any reentrancy. */
- acquire_global_objects_lock(runtime);
-
- /* Swap to the main interpreter, if necessary. */
- PyThreadState *oldts = NULL;
- if (!_Py_IsMainInterpreter(interp)) {
- PyThreadState *main_tstate = bind_global_objects_state(runtime);
-
- oldts = _PyThreadState_Swap(runtime, main_tstate);
- assert(oldts != NULL);
- assert(!_Py_IsMainInterpreter(oldts->interp));
-
- /* The limitations of the global objects thread state apply
- from this point to the point we swap back to oldts. */
- }
-
- /* This might trigger a resize, which is why we must "acquire"
- the global object state. Also note that PyDict_SetDefault()
- must be compatible with our reentrancy and global objects state
- constraints. */
- PyObject *actual = PyDict_SetDefault(dict, key, value);
- if (actual == NULL) {
- /* Raising an exception from one interpreter in another
- is problematic, so we clear it and let the caller deal
- with the returned NULL. */
- assert(PyErr_ExceptionMatches(PyExc_MemoryError));
- PyErr_Clear();
- }
-
- /* Swap back, it it wasn't in the main interpreter already. */
- if (oldts != NULL) {
- // The returned tstate should be _PyRuntime.cached_objects.main_tstate.
- _PyThreadState_Swap(runtime, oldts);
-
- unbind_global_objects_state(runtime);
- }
-
- release_global_objects_lock(runtime);
-
- // XXX Immortalize the key and value.
-
- return actual;
-}
-
-
/*************************************/
/* the per-interpreter runtime state */
/*************************************/
@@ -1335,7 +1217,8 @@ free_threadstate(PyThreadState *tstate)

static void
init_threadstate(PyThreadState *tstate,
- PyInterpreterState *interp, uint64_t id)
+ PyInterpreterState *interp, uint64_t id,
+ PyThreadState *next)
{
if (tstate->_status.initialized) {
Py_FatalError("thread state already initialized");
@@ -1344,13 +1227,18 @@ init_threadstate(PyThreadState *tstate,
assert(interp != NULL);
tstate->interp = interp;

- // next/prev are set in add_threadstate().
- assert(tstate->next == NULL);
- assert(tstate->prev == NULL);
-
assert(id > 0);
tstate->id = id;

+ assert(interp->threads.head == tstate);
+ assert((next != NULL && id != 1) || (next == NULL && id == 1));
+ if (next != NULL) {
+ assert(next->prev == NULL || next->prev == tstate);
+ next->prev = tstate;
+ }
+ tstate->next = next;
+ assert(tstate->prev == NULL);
+
// thread_id and native_thread_id are set in bind_tstate().

tstate->py_recursion_limit = interp->ceval.recursion_limit,
@@ -1371,22 +1259,6 @@ init_threadstate(PyThreadState *tstate,
tstate->_status.initialized = 1;
}

-static void
-add_threadstate(PyInterpreterState *interp, PyThreadState *tstate,
- PyThreadState *next)
-{
- assert(interp->threads.head != tstate);
- assert((next != NULL && tstate->id != 1) ||
- (next == NULL && tstate->id == 1));
- if (next != NULL) {
- assert(next->prev == NULL || next->prev == tstate);
- next->prev = tstate;
- }
- tstate->next = next;
- assert(tstate->prev == NULL);
- interp->threads.head = tstate;
-}
-
static PyThreadState *
new_threadstate(PyInterpreterState *interp)
{
@@ -1426,9 +1298,9 @@ new_threadstate(PyInterpreterState *interp)
&initial._main_interpreter._initial_thread,
sizeof(*tstate));
}
+ interp->threads.head = tstate;

- init_threadstate(tstate, interp, id);
- add_threadstate(interp, tstate, old_head);
+ init_threadstate(tstate, interp, id, old_head);

HEAD_UNLOCK(runtime);
if (!used_newtstate) {
@@ -1475,33 +1347,6 @@ _PyThreadState_Init(PyThreadState *tstate)
Py_FatalError("_PyThreadState_Init() is for internal use only");
}

-void
-_PyThreadState_InitDetached(PyThreadState *tstate, PyInterpreterState *interp)
-{
- _PyRuntimeState *runtime = interp->runtime;
-
- HEAD_LOCK(runtime);
- interp->threads.next_unique_id += 1;
- uint64_t id = interp->threads.next_unique_id;
- HEAD_UNLOCK(runtime);
-
- init_threadstate(tstate, interp, id);
- // We do not call add_threadstate().
-}
-
-
-static void
-clear_datastack(PyThreadState *tstate)
-{
- _PyStackChunk *chunk = tstate->datastack_chunk;
- tstate->datastack_chunk = NULL;
- while (chunk != NULL) {
- _PyStackChunk *prev = chunk->previous;
- _PyObject_VirtualFree(chunk, chunk->size);
- chunk = prev;
- }
-}
-
void
PyThreadState_Clear(PyThreadState *tstate)
{
@@ -1576,6 +1421,7 @@ PyThreadState_Clear(PyThreadState *tstate)
// XXX Do it as early in the function as possible.
}

+
/* Common code for PyThreadState_Delete() and PyThreadState_DeleteCurrent() */
static void
tstate_delete_common(PyThreadState *tstate)
@@ -1608,25 +1454,17 @@ tstate_delete_common(PyThreadState *tstate)
unbind_tstate(tstate);

// XXX Move to PyThreadState_Clear()?
- clear_datastack(tstate);
+ _PyStackChunk *chunk = tstate->datastack_chunk;
+ tstate->datastack_chunk = NULL;
+ while (chunk != NULL) {
+ _PyStackChunk *prev = chunk->previous;
+ _PyObject_VirtualFree(chunk, chunk->size);
+ chunk = prev;
+ }

tstate->_status.finalized = 1;
}

-void
-_PyThreadState_ClearDetached(PyThreadState *tstate)
-{
- assert(!tstate->_status.bound);
- assert(!tstate->_status.bound_gilstate);
- assert(tstate->datastack_chunk == NULL);
- assert(tstate->thread_id == 0);
- assert(tstate->native_thread_id == 0);
- assert(tstate->next == NULL);
- assert(tstate->prev == NULL);
-
- PyThreadState_Clear(tstate);
- clear_datastack(tstate);
-}

static void
zapthreads(PyInterpreterState *interp)

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