gh-158370: Implement the context manager protocol for Interpreter objects

Doc/library/concurrent.interpreters.rst

@@ -240,6 +240,16 @@ Interpreter objects
    Generally, :class:`Interpreter` shouldn't be called directly.
    Instead, use :func:`create` or one of the other module functions.
 
+   :class:`!Interpreter` objects support the :term:`context manager`
+   protocol. Exiting the :keyword:`with` block calls :meth:`close`::
+
+      with interpreters.create() as interp:
+          interp.exec('print("hello")')
+
+   .. versionchanged:: next
+      Added support for using :class:`!Interpreter` objects in
+      a :term:`context manager`.
+
    .. attribute:: id
 
       (read-only)
@@ -352,33 +362,32 @@ Creating an interpreter and running code in it::
 
     from concurrent import interpreters
 
-    interp = interpreters.create()
-
-    # Run in the current OS thread.
+    with interpreters.create() as interp:
+        # Run in the current OS thread.
 
-    interp.exec('print("spam!")')
+        interp.exec('print("spam!")')
 
-    interp.exec("""if True:
-        print('spam!')
-        """)
+        interp.exec("""if True:
+            print('spam!')
+            """)
 
-    from textwrap import dedent
-    interp.exec(dedent("""
-        print('spam!')
-        """))
+        from textwrap import dedent
+        interp.exec(dedent("""
+            print('spam!')
+            """))
 
-    def run(arg):
-        return arg
+        def run(arg):
+            return arg
 
-    res = interp.call(run, 'spam!')
-    print(res)
+        res = interp.call(run, 'spam!')
+        print(res)
 
-    def run():
-        print('spam!')
+        def run():
+            print('spam!')
 
-    interp.call(run)
+        interp.call(run)
 
-    # Run in new OS thread.
+        # Run in new OS thread.
 
-    t = interp.call_in_thread(run)
-    t.join()
+        t = interp.call_in_thread(run)
+        t.join()

Doc/whatsnew/3.16.rst

@@ -151,6 +151,13 @@ concurrent.futures
   Use method :meth:`!close` to explicitly close the iterator.
   (Contributed by xzmeng and Serhiy Storchaka in :gh:`108518`.)
 
+concurrent.interpreters
+-----------------------
+
+* :class:`~concurrent.interpreters.Interpreter` objects now support the
+  :term:`context manager` protocol. Exiting the :keyword:`with` block calls
+  :meth:`~concurrent.interpreters.Interpreter.close`.
+  (Contributed by Peter Bierma in :gh:`158370`.)
 
 csv
 ---

Lib/concurrent/interpreters/__init__.py

@@ -192,6 +192,12 @@ def close(self):
         """
         return _interpreters.destroy(self._id, restrict=True)
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc_info):
+        self.close()
+
     def prepare_main(self, ns=None, /, **kwargs):
         """Bind the given values into the interpreter's __main__.
 

Lib/test/test_interpreters/test_api.py

@@ -832,6 +832,31 @@ def task():
         assert_python_ok('-c', code)
 
 
+class TestInterpreterContextManager(TestBase):
+
+    def test_basic(self):
+        main, = interpreters.list_all()
+        with interpreters.create() as interp:
+            self.assertIsInstance(interp, interpreters.Interpreter)
+            self.assertEqual(interpreters.list_all(), [main, interp])
+        self.assertEqual(interpreters.list_all(), [main])
+        with self.assertRaises(InterpreterNotFoundError):
+            interp.exec('pass')
+
+    def test_exception(self):
+        main, = interpreters.list_all()
+        with self.assertRaises(ZeroDivisionError):
+            with interpreters.create() as interp:
+                1/0
+        self.assertEqual(interpreters.list_all(), [main])
+
+    def test_main(self):
+        main, = interpreters.list_all()
+        with self.assertRaises(InterpreterError):
+            with main:
+                pass
+
+
 class TestInterpreterPrepareMain(TestBase):
 
     def test_empty(self):

Misc/NEWS.d/next/Library/2026-09-28-00-00-00.gh-issue-158370.ctxmgr.rst

@@ -0,0 +1,2 @@
+:class:`concurrent.interpreters.Interpreter` objects now support the
+:term:`context manager` protocol.