Isolate all logic in _threadmodule

Author: mpage

Include/cpython/pystate.h

@@ -161,18 +161,6 @@ struct _ts {
      */
     uintptr_t critical_section;
 
-    /* Boolean storing whether or not this is a daemon thread. */
-    int is_daemon;
-
-    /* Set when the tstate has been cleared and unlinked from the list of
-     * active tstates.
-     *
-     * This is used by _PyInterpreterState_WaitForThreads to wait for all
-     * non-daemon threads to finish. It cannot be a PyObject because its
-     * lifetime exceeds the tstate to which it is bound.
-     */
-    struct _PyEventRc *done_event;
-
     int coroutine_origin_tracking_depth;
 
     PyObject *async_gen_firstiter;

Include/internal/pycore_interp.h

@@ -302,7 +302,6 @@ PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_LookUpID(int64_t);
 PyAPI_FUNC(int) _PyInterpreterState_IDInitref(PyInterpreterState *);
 PyAPI_FUNC(int) _PyInterpreterState_IDIncref(PyInterpreterState *);
 PyAPI_FUNC(void) _PyInterpreterState_IDDecref(PyInterpreterState *);
-PyAPI_FUNC(void) _PyInterpreterState_WaitForThreads(PyInterpreterState *);
 
 extern const PyConfig* _PyInterpreterState_GetConfig(PyInterpreterState *interp);
 

Include/internal/pycore_pythread.h

@@ -78,7 +78,7 @@ struct _pythread_runtime_state {
     } stubs;
 #endif
 
-    // Linked list of ThreadHandleObjects
+    // Linked list of ThreadHandles
     struct llist_node handles;
 };
 

Lib/threading.py

@@ -37,8 +37,9 @@
 _allocate_lock = _thread.allocate_lock
 _LockType = _thread.LockType
 _thread_shutdown = _thread._shutdown
-_get_thread_handle = _thread._get_thread_handle
+_make_thread_handle = _thread._make_thread_handle
 get_ident = _thread.get_ident
+_get_main_thread_ident = _thread._get_main_thread_ident
 _is_main_interpreter = _thread._is_main_interpreter
 try:
     get_native_id = _thread.get_native_id
@@ -1346,8 +1347,8 @@ class _MainThread(Thread):
     def __init__(self):
         Thread.__init__(self, name="MainThread", daemon=False)
         self._started.set()
-        self._set_ident()
-        self._handle = _get_thread_handle()
+        self._ident = _get_main_thread_ident()
+        self._handle = _make_thread_handle(self._ident)
         if _HAVE_THREAD_NATIVE_ID:
             self._set_native_id()
         with _active_limbo_lock:
@@ -1395,7 +1396,7 @@ def __init__(self):
                         daemon=_daemon_threads_allowed())
         self._started.set()
         self._set_ident()
-        self._handle = _get_thread_handle()
+        self._handle = _make_thread_handle(self._ident)
         if _HAVE_THREAD_NATIVE_ID:
             self._set_native_id()
         with _active_limbo_lock:
@@ -1529,16 +1530,8 @@ def _shutdown():
     for atexit_call in reversed(_threading_atexits):
         atexit_call()
 
-    # Main thread
-    if _main_thread.ident == get_ident():
+    if _is_main_interpreter():
         _main_thread._handle._set_done()
-    else:
-        # bpo-1596321: _shutdown() must be called in the main thread.
-        # If the threading module was not imported by the main thread,
-        # _main_thread is the thread which imported the threading module.
-        # In this case, ignore _main_thread, similar behavior than for threads
-        # spawned by C libraries or using _thread.start_new_thread().
-        pass
 
     # Wait for all non-daemon threads to exit.
     _thread_shutdown()

Misc/NEWS.d/next/Library/2024-02-01-03-09-38.gh-issue-114271.raCkt5.rst

@@ -1 +1,7 @@
 Fix a race in ``threading.Thread.join()``.
+
+``threading._MainThread`` now always represents the main thread of the main
+interpreter.
+
+``PyThreadState.on_delete`` and ``PyThreadState.on_delete_data`` have been
+removed.