sobolevn · Jun 21, 2025 · Jun 18, 2025 · Jun 18, 2025 · Jun 18, 2025 · Jun 18, 2025
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
@@ -1185,6 +1185,9 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    ``cache_tag`` is set to ``None``, it indicates that module caching should
    be disabled.
 
+   *supports_isolated_interpreters* is a boolean value, whether
+   this implementation supports :pep:`734`. It is always ``True`` for CPython.
+
    :data:`sys.implementation` may contain additional attributes specific to
    the Python implementation.  These non-standard attributes must start with
    an underscore, and are not described here.  Regardless of its contents,
@@ -1194,6 +1197,9 @@ always available. Unless explicitly noted otherwise, all variables are read-only
 
    .. versionadded:: 3.3
 
+   .. versionchanged:: 3.14
+      Added ``supports_isolated_interpreters`` field.
+
    .. note::
 
       The addition of new required attributes must go through the normal PEP

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
@@ -1087,6 +1087,11 @@ def test_implementation(self):
         self.assertEqual(sys.implementation.name,
                          sys.implementation.name.lower())
 
+    @test.support.cpython_only
+    def test_supports_isolated_interpreters(self):
+        # https://peps.python.org/pep-0734
+        self.assertIs(sys.implementation.supports_isolated_interpreters, True)
+
     @test.support.cpython_only
     def test_debugmallocstats(self):
         # Test sys._debugmallocstats()

diff --git a/Misc/NEWS.d/next/Library/2025-06-18-13-58-13.gh-issue-135645.109nff.rst b/Misc/NEWS.d/next/Library/2025-06-18-13-58-13.gh-issue-135645.109nff.rst
@@ -0,0 +1,2 @@
+Added ``supports_isolated_interpreters`` field to
+:data:`sys.implementation`.
@@ -3602,6 +3602,11 @@ make_impl_info(PyObject *version_info)
         goto error;
 #endif
 
+    res = PyDict_SetItemString(impl_info, "supports_isolated_interpreters",
+                               Py_NewRef(Py_True));  // PEP-734
+    if (res < 0)
+        goto error;
+
     /* dict ready */
 
     ns = _PyNamespace_New(impl_info);
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Added ``supports_isolated_interpreters`` field to
		:data:`sys.implementation`.