https://github.com/python/cpython/commit/5d8739e956cd20d3860133b384518a3c5c74e5ae
commit: 5d8739e956cd20d3860133b384518a3c5c74e5ae
branch: main
author: Kumar Aditya <[email protected]>
committer: kumaraditya303 <[email protected]>
date: 2024-10-12T12:40:34+05:30
summary:
gh-111924: use atomics for interp id refcounting (#125321)
files:
M Include/internal/pycore_interp.h
M Python/pystate.c
diff --git a/Include/internal/pycore_interp.h b/Include/internal/pycore_interp.h
index d7e584094f7839..36cd71e5a007d5 100644
--- a/Include/internal/pycore_interp.h
+++ b/Include/internal/pycore_interp.h
@@ -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
@@ -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);
diff --git a/Python/pystate.c b/Python/pystate.c
index 45e79ade7b6035..5d94b7714bd607 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -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;
@@ -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;
@@ -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);
@@ -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);
@@ -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;
@@ -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);
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