fix: Handle SIGTERM more gracefully in watchmedo

README.rst

@@ -33,9 +33,9 @@ as command-line arguments and logs events generated:
         try:
             while True:
                 time.sleep(1)
-        except KeyboardInterrupt:
+        finally:
             observer.stop()
-        observer.join()
+            observer.join()
 
 
 Shell Utilities

changelog.rst

@@ -12,7 +12,8 @@ Changelog
 - Replace mutable default arguments with ``if None`` implementation (`#677 <https://github.com/gorakhargosh/watchdog/pull/677>`_)
 - Expand tests to Python 2.7 and 3.5-3.10 for GNU/Linux, macOS and Windows
 - [mac] Performance improvements for the `fsevents` module (`#680 <https://github.com/gorakhargosh/watchdog/pull/680>`_)
-- Thanks to our beloved contributors: @Sraw, @CCP-Aporia, @BoboTiG
+- Handle shutdown events from SIGTERM and SIGINT to `watchmedo` more reliably (`#693 <https://github.com/gorakhargosh/watchdog/pull/693>`_)
+- Thanks to our beloved contributors: @Sraw, @CCP-Aporia, @BoboTiG, @maybe-sybr
 
 
 0.10.3

docs/source/examples/logger.py

@@ -14,6 +14,6 @@
 try:
     while True:
         time.sleep(1)
-except KeyboardInterrupt:
+finally:
     observer.stop()
-observer.join()
+    observer.join()

docs/source/examples/patterns.py

@@ -25,6 +25,6 @@ def on_any_event(self, event):
 try:
     while True:
         time.sleep(1)
-except KeyboardInterrupt:
+finally:
     observer.stop()
-observer.join()
+    observer.join()

docs/source/examples/simple.py

@@ -37,6 +37,6 @@ def on_modified(self, event):
 try:
     while True:
         time.sleep(1)
-except KeyboardInterrupt:
+finally:
     observer.stop()
-observer.join()
+    observer.join()

docs/source/quickstart.rst

@@ -48,8 +48,8 @@ file system changes and simply log them to the console::
         try:
             while observer.isAlive():
                 observer.join(1)
-        except KeyboardInterrupt:
+        finally:
             observer.stop()
-        observer.join()
+            observer.join()
 
 To stop the program, press Control-C.

src/watchdog/utils/__init__.py

@@ -62,6 +62,13 @@ class UnsupportedLibc(Exception):
     pass
 
 
+class WatchdogShutdown(Exception):
+    """
+    Semantic exception used to signal an external shutdown event.
+    """
+    pass
+
+
 class BaseThread(threading.Thread):
     """ Convenience class for creating stoppable threads. """
 

src/watchdog/watchmedo.py

@@ -38,7 +38,7 @@
 
 from argh import arg, aliases, ArghParser, expects_obj
 from watchdog.version import VERSION_STRING
-from watchdog.utils import load_class
+from watchdog.utils import WatchdogShutdown, load_class
 
 
 logging.basicConfig(level=logging.INFO)
@@ -117,7 +117,7 @@ def observe_with(observer, event_handler, pathnames, recursive):
     try:
         while True:
             time.sleep(1)
-    except KeyboardInterrupt:
+    except WatchdogShutdown:
         observer.stop()
     observer.join()
 
@@ -198,7 +198,7 @@ def tricks_from(args):
     try:
         while True:
             time.sleep(1)
-    except KeyboardInterrupt:
+    except WatchdogShutdown:
         for o in observers:
             o.unschedule_all()
             o.stop()
@@ -531,12 +531,18 @@ def auto_restart(args):
     else:
         stop_signal = int(args.signal)
 
-    # Handle SIGTERM in the same manner as SIGINT so that
-    # this program has a chance to stop the child process.
-    def handle_sigterm(_signum, _frame):
-        raise KeyboardInterrupt()
+    # Handle termination signals by raising a semantic exception which will
+    # allow us to gracefully unwind and stop the observer
+    termination_signals = {signal.SIGTERM, signal.SIGINT}
 
-    signal.signal(signal.SIGTERM, handle_sigterm)
+    def handler_termination_signal(_signum, _frame):
+        # Neuter all signals so that we don't attempt a double shutdown
+        for signum in termination_signals:
+            signal.signal(signum, signal.SIG_IGN)
+        raise WatchdogShutdown
+
+    for signum in termination_signals:
+        signal.signal(signum, handler_termination_signal)
 
     patterns, ignore_patterns = parse_patterns(args.patterns,
                                                args.ignore_patterns)
@@ -550,8 +556,12 @@ def handle_sigterm(_signum, _frame):
                                kill_after=args.kill_after)
     handler.start()
     observer = Observer(timeout=args.timeout)
-    observe_with(observer, handler, args.directories, args.recursive)
-    handler.stop()
+    try:
+        observe_with(observer, handler, args.directories, args.recursive)
+    except WatchdogShutdown:
+        pass
+    finally:
+        handler.stop()
 
 
 epilog = """Copyright 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>.