Merge pull request #6 from ngoldbaum/fix-deadlock4

Fix deadlock4

Author: ngoldbaum

src/watchdog/observers/winapi.py

@@ -293,9 +293,12 @@ def _generate_observed_path_deleted_event() -> tuple[bytes, int]:
     return buff.raw, event_size
 
 
+OPEN_HANDLES = set()
+
+
 def get_directory_handle(path: str) -> HANDLE:
     """Returns a Windows handle to the specified directory path."""
-    return CreateFileW(
+    handle = CreateFileW(
         path,
         FILE_LIST_DIRECTORY,
         WATCHDOG_FILE_SHARE_FLAGS,
@@ -304,9 +307,16 @@ def get_directory_handle(path: str) -> HANDLE:
         WATCHDOG_FILE_FLAGS,
         None,
     )
+    OPEN_HANDLES.add(handle)
+    return handle
 
 
 def close_directory_handle(handle: HANDLE) -> None:
+    try:
+        OPEN_HANDLES.remove(handle)
+    except KeyError:
+        # another thread already closed the handle
+        return
     try:
         CancelIoEx(handle, None)  # force ReadDirectoryChangesW to return
         CloseHandle(handle)

tests/conftest.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import contextlib
+import faulthandler
 import gc
 import os
 import threading
@@ -27,10 +28,15 @@ def _no_thread_leaks():
     We do not use pytest-threadleak because it is not reliable.
     """
     old_thread_count = threading.active_count()
+
     yield
-    gc.collect()  # Clear the stuff from other function-level fixtures
-    assert threading.active_count() == old_thread_count  # Only previously existing threads
 
+    # Clear the stuff from other function-level fixtures
+    gc.collect()
+
+    # Only previously existing threads, allowing for threads that were
+    # being cleaned up while this test was starting
+    assert threading.active_count() <= old_thread_count
 
 @pytest.fixture(autouse=True)
 def _no_warnings(recwarn):