From 4c4b83d319493b64d5db2dd4bb0a2635cd73823c Mon Sep 17 00:00:00 2001
From: Zedong <xihaolong@gmail.com>
Date: Sun, 1 Nov 2026 23:57:51 +0800
Subject: [PATCH] fix(llm): stop Codex process before closing read pipes

---
 openevolve/llm/codex_app_server.py | 20 +++++---
 tests/test_codex_shutdown.py       | 81 ++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+), 6 deletions(-)
 create mode 100644 tests/test_codex_shutdown.py

diff --git a/openevolve/llm/codex_app_server.py b/openevolve/llm/codex_app_server.py
index b0800bdbc..726f0d8f3 100644
--- a/openevolve/llm/codex_app_server.py
+++ b/openevolve/llm/codex_app_server.py
@@ -168,20 +168,28 @@ def _send(self, payload: Dict[str, Any]) -> None:
             raise RuntimeError(f"Failed to write to codex app-server: {e}. {self.stderr_summary()}")
 
     def close(self) -> None:
-        for stream in (self.proc.stdin, self.proc.stdout, self.proc.stderr):
-            try:
-                if stream:
-                    stream.close()
-            except (OSError, ValueError):
-                pass
+        try:
+            if self.proc.stdin:
+                self.proc.stdin.close()
+        except (OSError, ValueError):
+            pass
+        # Closing stdout while the reader is blocked in it can wait forever for
+        # the stream's lock. Stop and reap the child before closing its read pipes.
         try:
             self.proc.terminate()
             self.proc.wait(timeout=5)
         except Exception:
             try:
                 self.proc.kill()
+                self.proc.wait(timeout=5)
             except Exception:
                 pass
+        for stream in (self.proc.stdout, self.proc.stderr):
+            try:
+                if stream:
+                    stream.close()
+            except (OSError, ValueError):
+                pass
 
 
 class CodexAppServerLLM(LLMInterface):
diff --git a/tests/test_codex_shutdown.py b/tests/test_codex_shutdown.py
new file mode 100644
index 000000000..d4202ce4f
--- /dev/null
+++ b/tests/test_codex_shutdown.py
@@ -0,0 +1,81 @@
+"""Real-process regressions for bounded app-server shutdown."""
+
+import asyncio
+import os
+import subprocess
+import sys
+import threading
+import time
+import unittest
+from unittest.mock import patch
+
+from openevolve.llm.codex_app_server import CodexAppServerLLM, _AppServerSession
+
+
+class TestCodexShutdown(unittest.TestCase):
+    def _check_shutdown(self, request_timeout=False, ignore_termination=False):
+        script = "import time; "
+        if ignore_termination:
+            script += "import signal; signal.signal(signal.SIGTERM, signal.SIG_IGN); "
+        script += 'print(\'{"method":"ready"}\', flush=True); time.sleep(60)'
+        process = subprocess.Popen(
+            [sys.executable, "-u", "-c", script],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            text=True,
+        )
+        session = _AppServerSession(process)
+        failures = []
+        worker = None
+
+        def close_or_timeout():
+            try:
+                if request_timeout:
+                    model = CodexAppServerLLM()
+                    with patch.object(model, "_start_session", return_value=session):
+                        model._run_app_server("test", timeout=0.05)
+                else:
+                    session.close()
+            except BaseException as error:
+                failures.append(error)
+
+        try:
+            self.assertEqual(session.next_message(time.monotonic() + 5)["method"], "ready")
+            worker = threading.Thread(target=close_or_timeout, daemon=True)
+            worker.start()
+            worker.join(timeout=8 if ignore_termination else 2)
+            returned_without_rescue = not worker.is_alive()
+            exited_without_rescue = process.poll() is not None
+        finally:
+            # Even the broken implementation must not leave a sleeping child behind.
+            if process.poll() is None:
+                process.kill()
+            process.wait(timeout=5)
+            if worker is not None:
+                worker.join(timeout=5)
+            session._reader.join(timeout=5)
+
+        self.assertTrue(returned_without_rescue, "shutdown blocked before terminating the child")
+        self.assertTrue(exited_without_rescue, "shutdown returned without reaping the child")
+        self.assertFalse(worker.is_alive())
+        self.assertFalse(session._reader.is_alive())
+        if request_timeout:
+            self.assertEqual(len(failures), 1)
+            self.assertIsInstance(failures[0], asyncio.TimeoutError)
+        else:
+            self.assertEqual(failures, [])
+
+    def test_close_terminates_child_before_closing_reader_pipe(self):
+        self._check_shutdown()
+
+    def test_request_timeout_can_finish_cleanup(self):
+        self._check_shutdown(request_timeout=True)
+
+    @unittest.skipUnless(os.name == "posix", "POSIX signal handling required")
+    def test_shutdown_kills_and_reaps_child_ignoring_sigterm(self):
+        self._check_shutdown(ignore_termination=True)
+
+
+if __name__ == "__main__":
+    unittest.main()