Merge pull request #251 from chevah/250-inotify-close-block

Fix inotify stop dead lock. Closes #250

README.rst

@@ -162,6 +162,13 @@ Fork the `repository`_ on GitHub and send a pull request, or file an issue
 ticket at the `issue tracker`_. For general help and questions use the official
 `mailing list`_ or ask on `stackoverflow`_ with tag `python-watchdog`.
 
+Create and activate your virtual environment, then::
+
+    pip install pytest
+    pip install -e .
+    py.tests tests
+
+
 Supported Platforms
 -------------------
 * Linux 2.6 (inotify)

src/watchdog/observers/inotify.py

@@ -71,7 +71,7 @@
 
 import os
 import threading
-from .inotify_buffer import InotifyBuffer
+from .inotify_buffer import InotifyBuffer, STOP_EVENT
 
 from watchdog.observers.api import (
     EventEmitter,
@@ -130,6 +130,9 @@ def queue_events(self, timeout):
         with self._lock:
             event = self._inotify.read_event()
 
+            if event is STOP_EVENT:
+                return
+
             if isinstance(event, tuple):
                 move_from, move_to = event
                 src_path = self._decode_path(move_from.src_path)

src/watchdog/observers/inotify_buffer.py

@@ -21,6 +21,8 @@
 from watchdog.utils import DaemonThread
 from .inotify_c import Inotify
 
+STOP_EVENT = object()
+
 
 class _Worker(DaemonThread):
     """
@@ -94,6 +96,9 @@ def close(self):
         self._worker.stop()
         self._inotify.close()
         self._worker.join()
+        # Add the stop event to unblock the read_event which waits for
+        # events in the queue... even after inotify buffer is closed.
+        self._put(STOP_EVENT)
 
     def _put(self, elem):
         self._lock.acquire()

tests/test_inotify_buffer.py

@@ -20,10 +20,12 @@
 import pytest
 from tests import tmpdir, p  # pytest magic
 from .shell import mkdir, touch, mv
+from watchdog.observers.api import ObservedWatch
 from watchdog.utils import platform
 
 pytestmark = pytest.mark.skipif(not platform.is_linux(), reason="")
 if platform.is_linux():
+    from watchdog.observers.inotify import InotifyEmitter
     from watchdog.observers.inotify_buffer import InotifyBuffer
 
 
@@ -100,3 +102,23 @@ def test_move_internal_batch(p):
         assert frm.name == to.name
         i += 1
     inotify.close()
+
+
+def test_close_clean(tmpdir):
+    """
+    On InotifyBuffer.close() InotifyBuffer.read_event() is un-blocked so that
+    Inotify thread waiting for it can be closed.
+
+    This is also a test for Inotify.queue_events handling of STOP_EVENT and
+    InotifyBuffer.close() is test as side effect of Inotify.stop()
+    """
+    watch = ObservedWatch(path=tmpdir, recursive=False)
+    emitter = InotifyEmitter([], watch)
+    inotify_buffer = emitter._inotify
+    # Remove delay to speed up test.
+    inotify_buffer.delay = 0
+    emitter.start()
+
+    emitter.stop()
+    emitter.join(1)
+    assert not emitter.isAlive()