Skip to content

gh-111924: use atomics for interp id refcounting #125321

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Oct 12, 2024
Merged

gh-111924: use atomics for interp id refcounting #125321

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
750005f
use atomics
kumaraditya303 Oct 11, 2024
fdae5b8
fix decref
kumaraditya303 Oct 11, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 2 additions & 4 deletions Include/internal/pycore_interp.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -102,9 +102,8 @@ struct _is {
PyInterpreterState *next;

int64_t id;
int64_t id_refcount;
Py_ssize_t id_refcount;
int requires_idref;
PyThread_type_lock id_mutex;

#define _PyInterpreterState_WHENCE_NOTSET -1
#define _PyInterpreterState_WHENCE_UNKNOWN 0
Expand Down Expand Up @@ -318,8 +317,7 @@ _PyInterpreterState_SetFinalizing(PyInterpreterState *interp, PyThreadState *tst
PyAPI_FUNC(int64_t) _PyInterpreterState_ObjectToID(PyObject *);
PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_LookUpID(int64_t);
PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_LookUpIDObject(PyObject *);
PyAPI_FUNC(int) _PyInterpreterState_IDInitref(PyInterpreterState *);
PyAPI_FUNC(int) _PyInterpreterState_IDIncref(PyInterpreterState *);
PyAPI_FUNC(void) _PyInterpreterState_IDIncref(PyInterpreterState *);
PyAPI_FUNC(void) _PyInterpreterState_IDDecref(PyInterpreterState *);

PyAPI_FUNC(int) _PyInterpreterState_IsReady(PyInterpreterState *interp);
Expand Down
54 changes: 6 additions & 48 deletions Python/pystate.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -523,12 +523,6 @@ _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime)

_PyTypes_AfterFork();

/* bpo-42540: id_mutex is freed by _PyInterpreterState_Delete, which does
* not force the default allocator. */
if (_PyThread_at_fork_reinit(&runtime->interpreters.main->id_mutex) < 0) {
return _PyStatus_ERR("Failed to reinitialize runtime locks");
}

PyStatus status = gilstate_tss_reinit(runtime);
if (_PyStatus_EXCEPTION(status)) {
return status;
Expand Down Expand Up @@ -629,6 +623,8 @@ init_interpreter(PyInterpreterState *interp,
assert(id > 0 || (id == 0 && interp == runtime->interpreters.main));
interp->id = id;

interp->id_refcount = 0;

assert(runtime->interpreters.head == interp);
assert(next != NULL || (interp == runtime->interpreters.main));
interp->next = next;
Expand Down Expand Up @@ -989,10 +985,6 @@ PyInterpreterState_Delete(PyInterpreterState *interp)
}
HEAD_UNLOCK(runtime);

if (interp->id_mutex != NULL) {
PyThread_free_lock(interp->id_mutex);
}

_Py_qsbr_fini(interp);

_PyObject_FiniState(interp);
Expand Down Expand Up @@ -1031,9 +1023,6 @@ _PyInterpreterState_DeleteExceptMain(_PyRuntimeState *runtime)
// the "current" tstate to be set?
PyInterpreterState_Clear(interp); // XXX must activate?
zapthreads(interp);
if (interp->id_mutex != NULL) {
PyThread_free_lock(interp->id_mutex);
}
PyInterpreterState *prev_interp = interp;
interp = interp->next;
free_interpreter(prev_interp);
Expand Down Expand Up @@ -1247,9 +1236,6 @@ PyInterpreterState_GetID(PyInterpreterState *interp)
PyObject *
_PyInterpreterState_GetIDObject(PyInterpreterState *interp)
{
if (_PyInterpreterState_IDInitref(interp) != 0) {
return NULL;
};
int64_t interpid = interp->id;
if (interpid < 0) {
return NULL;
Expand All @@ -1259,50 +1245,22 @@ _PyInterpreterState_GetIDObject(PyInterpreterState *interp)
}


int
_PyInterpreterState_IDInitref(PyInterpreterState *interp)
{
if (interp->id_mutex != NULL) {
return 0;
}
interp->id_mutex = PyThread_allocate_lock();
if (interp->id_mutex == NULL) {
PyErr_SetString(PyExc_RuntimeError,
"failed to create init interpreter ID mutex");
return -1;
}
interp->id_refcount = 0;
return 0;
}


int
void
_PyInterpreterState_IDIncref(PyInterpreterState *interp)
{
if (_PyInterpreterState_IDInitref(interp) < 0) {
return -1;
}

PyThread_acquire_lock(interp->id_mutex, WAIT_LOCK);
interp->id_refcount += 1;
PyThread_release_lock(interp->id_mutex);
return 0;
_Py_atomic_add_ssize(&interp->id_refcount, 1);
}


void
_PyInterpreterState_IDDecref(PyInterpreterState *interp)
{
assert(interp->id_mutex != NULL);
_PyRuntimeState *runtime = interp->runtime;

PyThread_acquire_lock(interp->id_mutex, WAIT_LOCK);
assert(interp->id_refcount != 0);
interp->id_refcount -= 1;
int64_t refcount = interp->id_refcount;
PyThread_release_lock(interp->id_mutex);
Py_ssize_t refcount = _Py_atomic_add_ssize(&interp->id_refcount, -1);

if (refcount == 0 && interp->requires_idref) {
if (refcount == 1 && interp->requires_idref) {
PyThreadState *tstate =
_PyThreadState_NewBound(interp, _PyThreadState_WHENCE_FINI);

Expand Down
Loading