[pull] main from python:main

Doc/library/multiprocessing.rst

@@ -100,10 +100,10 @@ To show the individual process IDs involved, here is an expanded example::
 For an explanation of why the ``if __name__ == '__main__'`` part is
 necessary, see :ref:`multiprocessing-programming`.
 
-The arguments to :class:`Process` usually need to be unpickleable from within
-the child process. If you tried typing the above example directly into a REPL it
-could lead to an :exc:`AttributeError` in the child process trying to locate the
-*f* function in the ``__main__`` module.
+The arguments to :class:`Process` usually need to be picklable so they can be
+passed to the child process. If you tried typing the above example directly
+into a REPL it could lead to an :exc:`AttributeError` in the child process
+trying to locate the *f* function in the ``__main__`` module.
 
 
 .. _multiprocessing-start-methods:

Lib/test/test_email/test_email.py

@@ -4995,15 +4995,8 @@ def test_body_encode(self):
         # Try the convert argument, where input codec != output codec
         c = Charset('euc-jp')
         # With apologies to Tokio Kikuchi ;)
-        # XXX FIXME
-##         try:
-##             eq('\x1b$B5FCO;~IW\x1b(B',
-##                c.body_encode('\xb5\xc6\xc3\xcf\xbb\xfe\xc9\xd7'))
-##             eq('\xb5\xc6\xc3\xcf\xbb\xfe\xc9\xd7',
-##                c.body_encode('\xb5\xc6\xc3\xcf\xbb\xfe\xc9\xd7', False))
-##         except LookupError:
-##             # We probably don't have the Japanese codecs installed
-##             pass
+        eq('\x1b$B5FCO;~IW\x1b(B',
+           c.body_encode('\u83ca\u5730\u6642\u592b'))
         # Testing SF bug #625509, which we have to fake, since there are no
         # built-in encodings where the header encoding is QP but the body
         # encoding is not.

Lib/test/test_free_threading/test_pickle.py

@@ -0,0 +1,44 @@
+import pickle
+import threading
+import unittest
+
+from test.support import threading_helper
+
+
+@threading_helper.requires_working_threading()
+class TestPickleFreeThreading(unittest.TestCase):
+
+    def test_pickle_dumps_with_concurrent_dict_mutation(self):
+        # gh-146452: Pickling a dict while another thread mutates it
+        # used to segfault. batch_dict_exact() iterated dict items via
+        # PyDict_Next() which returns borrowed references, and a
+        # concurrent pop/replace could free the value before Py_INCREF
+        # got to it.
+        shared = {str(i): list(range(20)) for i in range(50)}
+
+        def dumper():
+            for _ in range(1000):
+                try:
+                    pickle.dumps(shared)
+                except RuntimeError:
+                    # "dictionary changed size during iteration" is expected
+                    pass
+
+        def mutator():
+            for j in range(1000):
+                key = str(j % 50)
+                shared[key] = list(range(j % 20))
+                if j % 10 == 0:
+                    shared.pop(key, None)
+                    shared[key] = [j]
+
+        threads = []
+        for _ in range(10):
+            threads.append(threading.Thread(target=dumper))
+        threads.append(threading.Thread(target=mutator))
+
+        with threading_helper.start_threads(threads):
+            pass
+
+if __name__ == "__main__":
+    unittest.main()

Misc/NEWS.d/next/Library/2026-03-26-09-30-00.gh-issue-146452.Y2N6qZ8J.rst

@@ -0,0 +1,2 @@
+Fix segfault in :mod:`pickle` when pickling a dictionary concurrently
+mutated by another thread in the free-threaded build.

Misc/NEWS.d/next/Library/2026-05-16-21-08-33.gh-issue-149921.I1yNML.rst

@@ -0,0 +1,2 @@
+Fix reference leaks in error paths of the :mod:`!_interpchannels` and
+:mod:`!_interpqueues` extension modules.

Modules/_interpchannelsmodule.c

@@ -2586,6 +2586,7 @@ static PyObject *
 _channelid_from_xid(_PyXIData_t *data)
 {
     struct _channelid_xid *xid = (struct _channelid_xid *)_PyXIData_DATA(data);
+    PyObject *cidobj = NULL;
 
     // It might not be imported yet, so we can't use _get_current_module().
     PyObject *mod = PyImport_ImportModule(MODULE_NAME_STR);
@@ -2595,11 +2596,10 @@ _channelid_from_xid(_PyXIData_t *data)
     assert(mod != Py_None);
     module_state *state = get_module_state(mod);
     if (state == NULL) {
-        return NULL;
+        goto done;
     }
 
     // Note that we do not preserve the "resolve" flag.
-    PyObject *cidobj = NULL;
     int err = newchannelid(state->ChannelIDType, xid->cid, xid->end,
                            _global_channels(), 0, 0,
                            (channelid **)&cidobj);

Modules/_interpqueuesmodule.c

@@ -1363,6 +1363,7 @@ _queueobj_from_xid(_PyXIData_t *data)
     if (mod == NULL) {
         mod = PyImport_ImportModule(MODULE_NAME_STR);
         if (mod == NULL) {
+            Py_DECREF(qidobj);
             return NULL;
         }
     }

Modules/_pickle.c

@@ -3452,7 +3452,7 @@ batch_dict(PickleState *state, PicklerObject *self, PyObject *iter, PyObject *or
  * Note that this currently doesn't work for protocol 0.
  */
 static int
-batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj)
+batch_dict_exact_impl(PickleState *state, PicklerObject *self, PyObject *obj)
 {
     PyObject *key = NULL, *value = NULL;
     int i;
@@ -3525,6 +3525,18 @@ batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj)
     return -1;
 }
 
+/* gh-146452: Wrap the dict iteration in a critical section to prevent
+   concurrent mutation from invalidating PyDict_Next() iteration state. */
+static int
+batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj)
+{
+    int ret;
+    Py_BEGIN_CRITICAL_SECTION(obj);
+    ret = batch_dict_exact_impl(state, self, obj);
+    Py_END_CRITICAL_SECTION();
+    return ret;
+}
+
 static int
 save_dict(PickleState *state, PicklerObject *self, PyObject *obj)
 {