Resolve handler close race condition at triggerer shutdown (apache#37206

)

At shutdown, a trigger may emit a "close" signal around the same time as logging.shutDown is called, so the handler may have been removed from the handlers by one thread when the other tries to delete it.

airflow/utils/log/trigger_handler.py

@@ -19,6 +19,7 @@
 
 import asyncio
 import logging
+from contextlib import suppress
 from contextvars import ContextVar
 from copy import copy
 from logging.handlers import QueueHandler
@@ -110,17 +111,16 @@ def close_one(self, trigger_id):
         h = self.handlers.get(trigger_id)
         if h:
             h.close()
-            del self.handlers[trigger_id]
+            with suppress(KeyError):  # race condition between `handle` and `close`
+                del self.handlers[trigger_id]
 
     def flush(self):
         for h in self.handlers.values():
             h.flush()
 
     def close(self):
         for trigger_id in list(self.handlers.keys()):
-            h = self.handlers[trigger_id]
-            h.close()
-            del self.handlers[trigger_id]
+            self.close_one(trigger_id)
 
 
 class LocalQueueHandler(QueueHandler):