Cleaner server shutdowns:

- Remove a workaround for Sanic server not always terminating cleanly
- Terminate worker threads before server stop
- Silent closing of watching WebSocket attempted to open while shutting down

cista/api.py

@@ -119,8 +119,12 @@ async def watch(req, ws):
         # Send updates
         while True:
             await ws.send(await q.get())
+    except RuntimeError as e:
+        if str(e) == "cannot schedule new futures after shutdown":
+            return  # Server shutting down, drop the WebSocket
+        raise
     finally:
-        del watching.pubsub[uuid]
+        watching.pubsub.pop(uuid, None)  # Remove whether it got added yet or not
 
 
 def subscribe(uuid, ws):

cista/app.py

@@ -43,14 +43,16 @@ async def main_start(app, loop):
     app.ctx.threadexec = ThreadPoolExecutor(
         max_workers=workers, thread_name_prefix="cista-ioworker"
     )
-    await watching.start(app, loop)
+    watching.start(app, loop)
 
 
-@app.after_server_stop
+# Sanic sometimes fails to execute after_server_stop, so we do it before instead (potentially interrupting handlers)
+@app.before_server_stop
 async def main_stop(app, loop):
     quit.set()
-    await watching.stop(app, loop)
+    watching.stop(app)
     app.ctx.threadexec.shutdown()
+    logger.debug("Cista worker threads all finished")
 
 
 @app.on_request

cista/serve.py

@@ -1,6 +1,5 @@
 import os
 import re
-import signal
 from pathlib import Path
 
 from sanic import Sanic
@@ -12,14 +11,6 @@ def run(*, dev=False):
     """Run Sanic main process that spawns worker processes to serve HTTP requests."""
     from .app import app
 
-    # Set up immediate exit on Ctrl+C for faster termination
-    def signal_handler(signum, frame):
-        print("\nReceived interrupt signal, exiting immediately...")
-        os._exit(0)
-
-    signal.signal(signal.SIGINT, signal_handler)
-    signal.signal(signal.SIGTERM, signal_handler)
-
     url, opts = parse_listen(config.config.listen)
     # Silence Sanic's warning about running in production rather than debug
     os.environ["SANIC_IGNORE_PRODUCTION_WARNING"] = "1"

cista/watching.py

@@ -440,7 +440,7 @@ def watcher_poll(loop):
         quit.wait(0.1 + 8 * dur)
 
 
-async def start(app, loop):
+def start(app, loop):
     global rootpath
     config.load_config()
     rootpath = config.config.path
@@ -454,6 +454,6 @@ async def start(app, loop):
     app.ctx.watcher.start()
 
 
-async def stop(app, loop):
+def stop(app):
     quit.set()
     app.ctx.watcher.join()