bpo-40232: Update PyOS_AfterFork_Child() to use _PyThread_at_fork_reinit() (GH-19450)

Include/internal/pycore_ceval.h

@@ -25,8 +25,9 @@ PyAPI_FUNC(int) _PyEval_AddPendingCall(
     int (*func)(void *),
     void *arg);
 PyAPI_FUNC(void) _PyEval_SignalAsyncExc(PyThreadState *tstate);
-PyAPI_FUNC(void) _PyEval_ReInitThreads(
+#ifdef HAVE_FORK
-    struct pyruntimestate *runtime);
+extern void _PyEval_ReInitThreads(struct pyruntimestate *runtime);
+#endif
 PyAPI_FUNC(void) _PyEval_SetCoroutineOriginTrackingDepth(
     PyThreadState *tstate,
     int new_depth);

Include/internal/pycore_import.h

@@ -10,7 +10,9 @@ PyAPI_FUNC(PyObject *) _PyImport_FindBuiltin(
     const char *name             /* UTF-8 encoded string */
     );
 
+#ifdef HAVE_FORK
 extern void _PyImport_ReInitLock(void);
+#endif
 extern void _PyImport_Cleanup(PyThreadState *tstate);
 
 #ifdef __cplusplus

Include/internal/pycore_runtime.h

@@ -117,8 +117,9 @@ PyAPI_DATA(_PyRuntimeState) _PyRuntime;
 PyAPI_FUNC(PyStatus) _PyRuntimeState_Init(_PyRuntimeState *runtime);
 PyAPI_FUNC(void) _PyRuntimeState_Fini(_PyRuntimeState *runtime);
 
+#ifdef HAVE_FORK
 PyAPI_FUNC(void) _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime);
-
+#endif
 
 /* Initialize _PyRuntimeState.
    Return NULL on success, or return an error message on failure. */

Python/ceval.c

@@ -397,6 +397,7 @@ PyEval_ReleaseThread(PyThreadState *tstate)
     drop_gil(&runtime->ceval, tstate);
 }
 
+#ifdef HAVE_FORK
 /* This function is called from PyOS_AfterFork_Child to destroy all threads
  * which are not running in the child process, and clear internal locks
  * which might be held by those threads.
@@ -416,14 +417,14 @@ _PyEval_ReInitThreads(_PyRuntimeState *runtime)
     take_gil(tstate);
 
     struct _pending_calls *pending = &tstate->interp->ceval.pending;
-    pending->lock = PyThread_allocate_lock();
+    if (_PyThread_at_fork_reinit(&pending->lock) < 0) {
-    if (pending->lock == NULL) {
         Py_FatalError("Can't initialize threads for pending calls");
     }
 
     /* Destroy all threads except the current one */
     _PyThreadState_DeleteExcept(runtime, tstate);
 }
+#endif
 
 /* This function is used to signal that async exceptions are waiting to be
    raised. */

Python/import.c

@@ -200,6 +200,7 @@ _PyImport_ReleaseLock(void)
     return 1;
 }
 
+#ifdef HAVE_FORK
 /* This function is called from PyOS_AfterFork_Child to ensure that newly
    created child processes do not share locks with the parent.
    We now acquire the import lock around fork() calls but on some platforms
@@ -209,8 +210,7 @@ void
 _PyImport_ReInitLock(void)
 {
     if (import_lock != NULL) {
-        import_lock = PyThread_allocate_lock();
+        if (_PyThread_at_fork_reinit(&import_lock) < 0) {
-        if (import_lock == NULL) {
             _Py_FatalErrorFunc(__func__, "failed to create a new lock");
         }
     }
@@ -229,6 +229,7 @@ _PyImport_ReInitLock(void)
         import_lock_level = 0;
     }
 }
+#endif
 
 /*[clinic input]
 _imp.lock_held

Python/pystate.c

@@ -132,6 +132,7 @@ _PyRuntimeState_Fini(_PyRuntimeState *runtime)
     PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 }
 
+#ifdef HAVE_FORK
 /* This function is called from PyOS_AfterFork_Child to ensure that
  * newly created child processes do not share locks with the parent.
  */
@@ -147,24 +148,25 @@ _PyRuntimeState_ReInitThreads(_PyRuntimeState *runtime)
     PyMemAllocatorEx old_alloc;
     _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 
-    runtime->interpreters.mutex = PyThread_allocate_lock();
+    int interp_mutex = _PyThread_at_fork_reinit(&runtime->interpreters.mutex);
-    runtime->interpreters.main->id_mutex = PyThread_allocate_lock();
+    int main_interp_id_mutex = _PyThread_at_fork_reinit(&runtime->interpreters.main->id_mutex);
-    runtime->xidregistry.mutex = PyThread_allocate_lock();
+    int xidregistry_mutex = _PyThread_at_fork_reinit(&runtime->xidregistry.mutex);
 
     PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
 
-    if (runtime->interpreters.mutex == NULL) {
+    if (interp_mutex < 0) {
         Py_FatalError("Can't initialize lock for runtime interpreters");
     }
 
-    if (runtime->interpreters.main->id_mutex == NULL) {
+    if (main_interp_id_mutex < 0) {
         Py_FatalError("Can't initialize ID lock for main interpreter");
     }
 
-    if (runtime->xidregistry.mutex == NULL) {
+    if (xidregistry_mutex < 0) {
         Py_FatalError("Can't initialize lock for cross-interpreter data registry");
     }
 }
+#endif
 
 #define HEAD_LOCK(runtime) \
     PyThread_acquire_lock((runtime)->interpreters.mutex, WAIT_LOCK)