gh-140025: Fix queue.SimpleQueue.__sizeof__() to return correct size (#143137)

Author: Aniketsy

Lib/test/test_queue.py

@@ -2,13 +2,15 @@
 # to ensure the Queue locks remain stable.
 import itertools
 import random
+import struct
 import threading
 import time
 import unittest
 import weakref
 from test.support import gc_collect, bigmemtest
 from test.support import import_helper
 from test.support import threading_helper
+from test import support
 
 # queue module depends on threading primitives
 threading_helper.requires_working_threading(module=True)
@@ -1031,6 +1033,14 @@ def test_is_default(self):
         self.assertIs(self.type2test, self.queue.SimpleQueue)
         self.assertIs(self.type2test, self.queue.SimpleQueue)
 
+    def test_simplequeue_sizeof(self):
+        q = self.type2test()
+        basesize = support.calcobjsize('?nnPnnP')
+        support.check_sizeof(self, q, basesize + struct.calcsize(8 * 'P'))
+        for _ in range(1000):
+            q.put(object())
+        support.check_sizeof(self, q, basesize + struct.calcsize(1024 * 'P'))
+
     def test_reentrancy(self):
         # bpo-14976: put() may be called reentrantly in an asynchronous
         # callback.

Misc/NEWS.d/next/Library/2026-01-02-09-32-43.gh-issue-140025.zOX58_.rst

@@ -0,0 +1 @@
+:mod:`queue`: Fix :meth:`!SimpleQueue.__sizeof__` computation.

Modules/_queuemodule.c

@@ -500,6 +500,22 @@ _queue_SimpleQueue_qsize_impl(simplequeueobject *self)
     return RingBuf_Len(&self->buf);
 }
 
+/*[clinic input]
+@critical_section
+_queue.SimpleQueue.__sizeof__ -> Py_ssize_t
+
+Returns size in memory, in bytes.
+[clinic start generated code]*/
+
+static Py_ssize_t
+_queue_SimpleQueue___sizeof___impl(simplequeueobject *self)
+/*[clinic end generated code: output=58ce4e3bbc078fd4 input=a3a7f05c9616598f]*/
+{
+    Py_ssize_t res = sizeof(simplequeueobject);
+    res += self->buf.items_cap * sizeof(PyObject *);
+    return res;
+}
+
 static int
 queue_traverse(PyObject *m, visitproc visit, void *arg)
 {
@@ -534,6 +550,7 @@ static PyMethodDef simplequeue_methods[] = {
     _QUEUE_SIMPLEQUEUE_PUT_METHODDEF
     _QUEUE_SIMPLEQUEUE_PUT_NOWAIT_METHODDEF
     _QUEUE_SIMPLEQUEUE_QSIZE_METHODDEF
+    _QUEUE_SIMPLEQUEUE___SIZEOF___METHODDEF
     {"__class_getitem__",    Py_GenericAlias,
     METH_O|METH_CLASS,       PyDoc_STR("See PEP 585")},
     {NULL,           NULL}              /* sentinel */