Improve server shutdown (#126)

* Cleaned up server shutdown process

* Fix exception on shutdown in Windows

client.py

@@ -3,7 +3,7 @@ import logging
 import threading
 from collections import deque
 
-from server import start_server
+from server import ZordonServer
 
 logger = logging.getLogger()
 
@@ -13,6 +13,7 @@ def __setup_buffer_handler():
 
     class BufferingHandler(logging.Handler, QObject):
         new_record = pyqtSignal(str)
+        flushOnClose = True
 
         def __init__(self, capacity=100):
             logging.Handler.__init__(self)
@@ -52,12 +53,25 @@ def __show_gui(buffer_handler):
     window.buffer_handler = buffer_handler
     window.show()
 
-    return app.exec()
+    exit_code = app.exec()
+
+    # cleanup: remove and close the GUI logging handler before interpreter shutdown
+    root_logger = logging.getLogger()
+    if buffer_handler in root_logger.handlers:
+        root_logger.removeHandler(buffer_handler)
+    try:
+        buffer_handler.close()
+    except Exception:
+        # never let logging cleanup throw during shutdown
+        pass
+
+    return exit_code
 
 if __name__ == '__main__':
     import sys
 
-    local_server_thread = threading.Thread(target=start_server, args=[True], daemon=True)
+    server = ZordonServer()
-    local_server_thread.start()
+    server.start_server()
     __show_gui(__setup_buffer_handler())
+    server.stop_server()
     sys.exit()

server.py

@@ -24,53 +24,15 @@ from src.version import APP_NAME, APP_VERSION, APP_REPO_NAME, APP_REPO_OWNER
 logger = logging.getLogger()
 
 
-def start_server(skip_updates=False) -> int:
+class ZordonServer:
-    """Initializes the application and runs it.
 
-    Args:
+    def __init__(self):
-        server_only: Run in server-only CLI mode. Default is False (runs in GUI mode).
+        # setup logging
+        logging.basicConfig(format='%(asctime)s: %(levelname)s: %(module)s: %(message)s', datefmt='%d-%b-%y %H:%M:%S',
+                            level=Config.server_log_level.upper())
+        logging.getLogger("requests").setLevel(logging.WARNING)  # suppress noisy requests/urllib3 logging
+        logging.getLogger("urllib3").setLevel(logging.WARNING)
 
-    Returns:
-        int: The exit status code.
-    """
-
-    def existing_process(process_name):
-        import psutil
-        current_pid = os.getpid()
-        current_process = psutil.Process(current_pid)
-        for proc in psutil.process_iter(['pid', 'name', 'ppid']):
-            proc_name = proc.info['name'].lower().rstrip('.exe')
-            if proc_name == process_name.lower() and proc.info['pid'] != current_pid:
-                if proc.info['pid'] == current_process.ppid():
-                    continue  # parent process
-                elif proc.info['ppid'] == current_pid:
-                    continue  # child process
-                else:
-                    return proc  # unrelated process
-        return None
-
-    # setup logging
-    logging.basicConfig(format='%(asctime)s: %(levelname)s: %(module)s: %(message)s', datefmt='%d-%b-%y %H:%M:%S',
-                        level=Config.server_log_level.upper())
-    logging.getLogger("requests").setLevel(logging.WARNING)  # suppress noisy requests/urllib3 logging
-    logging.getLogger("urllib3").setLevel(logging.WARNING)
-
-    # check for existing instance
-    existing_proc = existing_process(APP_NAME)
-    if existing_proc:
-        logger.fatal(f"Another instance of {APP_NAME} is already running (pid: {existing_proc.pid})")
-        sys.exit(1)
-
-    # check for updates
-    if not skip_updates:
-        update_thread = threading.Thread(target=check_for_updates, args=(APP_REPO_NAME, APP_REPO_OWNER, APP_NAME,
-                                                                         APP_VERSION))
-        update_thread.start()
-
-    # main start
-    logger.info(f"Starting {APP_NAME} Render Server")
-    return_code = 0
-    try:
         # Load Config YAML
         Config.setup_config_dir()
         Config.load_config(system_safe_path(os.path.join(Config.config_dir(), 'config.yaml')))
@@ -88,6 +50,34 @@ def start_server(skip_updates=False) -> int:
         logger.debug(f"Thumbs directory: {PreviewManager.storage_path}")
         logger.debug(f"Engines directory: {EngineManager.engines_path}")
 
+        self.api_server = None
+
+    def start_server(self):
+
+        def existing_process(process_name):
+            import psutil
+            current_pid = os.getpid()
+            current_process = psutil.Process(current_pid)
+            for proc in psutil.process_iter(['pid', 'name', 'ppid']):
+                proc_name = proc.info['name'].lower().rstrip('.exe')
+                if proc_name == process_name.lower() and proc.info['pid'] != current_pid:
+                    if proc.info['pid'] == current_process.ppid():
+                        continue  # parent process
+                    elif proc.info['ppid'] == current_pid:
+                        continue  # child process
+                    else:
+                        return proc  # unrelated process
+            return None
+
+        # check for existing instance
+        existing_proc = existing_process(APP_NAME)
+        if existing_proc:
+            err_msg = f"Another instance of {APP_NAME} is already running (pid: {existing_proc.pid})"
+            logger.fatal(err_msg)
+            raise ProcessLookupError(err_msg)
+
+        # main start
+        logger.info(f"Starting {APP_NAME} Render Server")
         # Set up the RenderQueue object
         RenderQueue.load_state(database_directory=system_safe_path(os.path.expanduser(Config.upload_folder)))
         ServerProxyManager.subscribe_to_listener()
@@ -97,9 +87,9 @@ def start_server(skip_updates=False) -> int:
         local_hostname = socket.gethostname()
 
         # configure and start API server
-        api_server = threading.Thread(target=start_api_server, args=(local_hostname,))
+        self.api_server = threading.Thread(target=start_api_server, args=(local_hostname,))
-        api_server.daemon = True
+        self.api_server.daemon = True
-        api_server.start()
+        self.api_server.start()
 
         # start zeroconf server
         ZeroconfServer.configure(f"_{APP_NAME.lower()}._tcp.local.", local_hostname, Config.port_number)
@@ -115,27 +105,26 @@ def start_server(skip_updates=False) -> int:
         logger.info(f"{APP_NAME} Render Server started - Hostname: {local_hostname}")
         RenderQueue.start()  # Start evaluating the render queue
 
-        # check for updates for render engines if configured or on first launch
+    def is_running(self):
-        # if Config.update_engines_on_launch or not EngineManager.get_engines():
+        return self.api_server and self.api_server.is_alive()
-        #     EngineManager.update_all_engines()
 
-        api_server.join()
+    def stop_server(self):
-
+        logger.info(f"{APP_NAME} Render Server is preparing to stop")
-    except KeyboardInterrupt:
-        pass
-    except Exception as e:
-        logging.error(f"Unhandled exception: {e}")
-        return_code = 1
-    finally:
-        # shut down gracefully
-        logger.info(f"{APP_NAME} Render Server is preparing to shut down")
         try:
+            ZeroconfServer.stop()
             RenderQueue.prepare_for_shutdown()
         except Exception as e:
             logger.exception(f"Exception during prepare for shutdown: {e}")
-        ZeroconfServer.stop()
         logger.info(f"{APP_NAME} Render Server has shut down")
-        return sys.exit(return_code)
 
 if __name__ == '__main__':
-    start_server()
+    server = ZordonServer()
+    try:
+        server.start_server()
+        server.api_server.join()
+    except KeyboardInterrupt:
+        pass
+    except Exception as e:
+        logger.error(f"Unhandled exception: {e}")
+    finally:
+        server.stop_server()