Issue #21619: Popen objects no longer leave a zombie after exit in the with

statement if the pipe was broken.  Patch by Martin Panter.

Lib/subprocess.py

@@ -896,8 +896,10 @@ class Popen(object):
             self.stdout.close()
         if self.stderr:
             self.stderr.close()
+        try:  # Flushing a BufferedWriter may raise an error
             if self.stdin:
                 self.stdin.close()
+        finally:
             # Wait for the process to terminate, to avoid zombies.
             self.wait()
 

Lib/test/test_subprocess.py

@@ -2521,6 +2521,21 @@ class ContextManagerTests(BaseTestCase):
                                   stderr=subprocess.PIPE) as proc:
                 pass
 
+    def test_broken_pipe_cleanup(self):
+        """Broken pipe error should not prevent wait() (Issue 21619)"""
+        proc = subprocess.Popen([sys.executable, "-c",
+                "import sys;"
+                "sys.stdin.close();"
+                "sys.stdout.close();"  # Signals that input pipe is closed
+        ], stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+        proc.stdout.read()  # Make sure subprocess has closed its input
+        proc.stdin.write(b"buffered data")
+        self.assertIsNone(proc.returncode)
+        self.assertRaises(BrokenPipeError, proc.__exit__, None, None, None)
+        self.assertEqual(0, proc.returncode)
+        self.assertTrue(proc.stdin.closed)
+        self.assertTrue(proc.stdout.closed)
+
 
 def test_main():
     unit_tests = (ProcessTestCase,

Misc/NEWS

@@ -13,6 +13,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #21619: Popen objects no longer leave a zombie after exit in the with
+  statement if the pipe was broken.  Patch by Martin Panter.
+
 - Issue #6639: Module-level turtle functions no longer raise TclError after
   closing the window.