runperiodic: Robustness against closed DB connections (#5314)

src/pretix/base/management/commands/runperiodic.py

@@ -38,6 +38,7 @@ import traceback
 from django.conf import settings
 from django.core.cache import cache
 from django.core.management.base import BaseCommand
+from django.db import close_old_connections
 from django.dispatch.dispatcher import NO_RECEIVERS
 
 from pretix.helpers.periodic import SKIPPED
@@ -79,6 +80,8 @@ class Command(BaseCommand):
                 self.stdout.write(f'INFO Running {name}…')
             t0 = time.time()
             try:
+                # Check if the DB connection is still good, it might be closed if the previous task took too long.
+                close_old_connections()
                 r = receiver(signal=periodic_task, sender=self)
             except Exception as err:
                 if isinstance(err, KeyboardInterrupt):