Server(fix[shutdown]): Close engine on kill-server

why: Non-daemon control-mode threads can hang pytest shutdown when the engine
process isn't closed.
what:
- close the engine in Server.kill cleanup
- ensure pytest fixtures close engines on teardown
- update control-mode engine tests to assert process termination

Author: tony

conftest.py

@@ -118,6 +118,8 @@ def control_sandbox(
     finally:
         with contextlib.suppress(Exception):
             server.kill()
+        with contextlib.suppress(Exception):
+            server.engine.close()
 
 
 @pytest.fixture

src/libtmux/pytest_plugin.py

@@ -163,7 +163,10 @@ def server(
     server = Server(socket_name=socket_name, engine=engine)
 
     def fin() -> None:
-        server.kill()
+        with contextlib.suppress(Exception):
+            server.kill()
+        with contextlib.suppress(Exception):
+            server.engine.close()
 
     request.addfinalizer(fin)
 

src/libtmux/server.py

@@ -7,6 +7,7 @@
 
 from __future__ import annotations
 
+import contextlib
 import logging
 import os
 import pathlib
@@ -440,7 +441,12 @@ def kill(self) -> None:
         >>> svr.is_alive()
         False
         """
-        self.cmd("kill-server")
+        try:
+            self.cmd("kill-server")
+        finally:
+            # Ensure engine resources (e.g., control-mode threads) are released.
+            with contextlib.suppress(Exception):
+                self.engine.close()
 
     def kill_session(self, target_session: str | int) -> Server:
         """Kill tmux session.

tests/test_control_mode_engine.py

@@ -66,14 +66,13 @@ def test_control_mode_engine_basic(tmp_path: pathlib.Path) -> None:
     )
 
     # cleanup
+    proc = engine.process
     server.kill()
-    # Engine process should terminate eventually (ControlModeEngine.close is called
-    # manually or via weakref/del)
-    # Server.kill() kills the tmux SERVER. The control mode client process should
-    # exit as a result.
-
-    engine.process.wait(timeout=2)
-    assert engine.process.poll() is not None
+    # Server.kill() now closes the engine, which should terminate the client.
+    assert proc is not None
+    proc.wait(timeout=2)
+    assert proc.poll() is not None
+    assert engine.process is None
 
 
 def test_control_mode_timeout(monkeypatch: pytest.MonkeyPatch) -> None:
@@ -188,9 +187,11 @@ def test_control_mode_custom_session_name(tmp_path: pathlib.Path) -> None:
     assert len(all_sessions) == 2
 
     # Cleanup
+    proc = engine.process
     server.kill()
-    assert engine.process is not None
-    engine.process.wait(timeout=2)
+    assert proc is not None
+    proc.wait(timeout=2)
+    assert engine.process is None
 
 
 def test_control_mode_control_session_existing(tmp_path: pathlib.Path) -> None:
@@ -221,9 +222,11 @@ def test_control_mode_control_session_existing(tmp_path: pathlib.Path) -> None:
     assert len(all_sessions) == 1  # Only shared_session
 
     # Cleanup
+    proc = control_engine.process
     server2.kill()
-    assert control_engine.process is not None
-    control_engine.process.wait(timeout=2)
+    assert proc is not None
+    proc.wait(timeout=2)
+    assert control_engine.process is None
 
 
 class RestartFixture(t.NamedTuple):