diff --git a/.github/workflows/_test.yml b/.github/workflows/_test.yml
index 88e3b194d..2efe2bc13 100644
--- a/.github/workflows/_test.yml
+++ b/.github/workflows/_test.yml
@@ -55,12 +55,6 @@ jobs:
           run: |
             ${{ matrix.platform.python_exec }} -m mypy python
         - name: Python tests
-          if: ${{ !startsWith(matrix.platform.runner, 'windows') }}
-          run: |
-            ${{ matrix.platform.python_exec }} -m pytest --capture=no python/cocoindex/tests
-        - name: Python tests (Windows cmd)
-          if: ${{ startsWith(matrix.platform.runner, 'windows') }}
-          shell: cmd  # Use `cmd` to run test for Windows, as PowerShell doesn't detect exit code by `os._exit(0)` correctly.
           run: |
             ${{ matrix.platform.python_exec }} -m pytest --capture=no python/cocoindex/tests
 
diff --git a/pyproject.toml b/pyproject.toml
index 9bf787734..a3d27d77c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,6 +15,7 @@ dependencies = [
     "python-dotenv>=1.1.0",
     "watchfiles>=1.1.0",
     "numpy>=1.23.2",
+    "psutil>=7.0.0",
 ]
 license = "Apache-2.0"
 license-files = ["THIRD_PARTY_NOTICES.html"]
diff --git a/python/cocoindex/subprocess_exec.py b/python/cocoindex/subprocess_exec.py
index 11cadf7eb..c60adfd2d 100644
--- a/python/cocoindex/subprocess_exec.py
+++ b/python/cocoindex/subprocess_exec.py
@@ -134,18 +134,27 @@ def _start_parent_watchdog(
     This runs in a background daemon thread so it never blocks pool work.
     """
 
+    import psutil  # type: ignore
+
+    if parent_pid is None:
+        parent_pid = os.getppid()
+
+    try:
+        p = psutil.Process(parent_pid)
+        # Cache create_time to defeat PID reuse.
+        created = p.create_time()
+    except psutil.Error:
+        # Parent already gone or not accessible
+        os._exit(1)
+
     def _watch() -> None:
         while True:
-            # If PPID changed (parent died and we were reparented), exit.
-            if os.getppid() != parent_pid:
-                os._exit(1)
-
-            # Best-effort liveness probe in case PPID was reused.
             try:
-                os.kill(parent_pid, 0)
-            except OSError:
+                # is_running() + same create_time => same process and still alive
+                if not (p.is_running() and p.create_time() == created):
+                    os._exit(1)
+            except psutil.NoSuchProcess:
                 os._exit(1)
-
             time.sleep(interval_seconds)
 
     threading.Thread(target=_watch, name="parent-watchdog", daemon=True).start()
diff --git a/python/cocoindex/tests/conftest.py b/python/cocoindex/tests/conftest.py
deleted file mode 100644
index 109898e07..000000000
--- a/python/cocoindex/tests/conftest.py
+++ /dev/null
@@ -1,38 +0,0 @@
-import pytest
-import typing
-import os
-import signal
-import sys
-
-
-@pytest.fixture(scope="session", autouse=True)
-def _cocoindex_windows_env_fixture(
-    request: pytest.FixtureRequest,
-) -> typing.Generator[None, None, None]:
-    """Shutdown the subprocess pool at exit on Windows."""
-
-    yield
-
-    if not sys.platform.startswith("win"):
-        return
-
-    try:
-        import cocoindex.subprocess_exec
-
-        original_sigint_handler = signal.getsignal(signal.SIGINT)
-        try:
-            signal.signal(signal.SIGINT, signal.SIG_IGN)
-            cocoindex.subprocess_exec.shutdown_pool_at_exit()
-
-            # If any test failed, let pytest exit normally with nonzero code
-            if request.session.testsfailed == 0:
-                os._exit(0)  # immediate success exit (skips atexit/teardown)
-
-        finally:
-            try:
-                signal.signal(signal.SIGINT, original_sigint_handler)
-            except ValueError:  # noqa: BLE001
-                pass
-
-    except (ImportError, AttributeError):  # noqa: BLE001
-        pass