Export tasks: Request new database connection after completing output

src/pretix/base/services/export.py

@@ -26,7 +26,7 @@ from typing import Any, Dict, Union
 from celery.exceptions import MaxRetriesExceededError
 from django.conf import settings
 from django.core.files.base import ContentFile
-from django.db import connection, transaction
+from django.db import close_old_connections, connection, transaction
 from django.dispatch import receiver
 from django.utils.timezone import now, override
 from django.utils.translation import gettext
@@ -86,6 +86,9 @@ def export(self, event: Event, fileid: str, provider: str, form_data: Dict[str,
                         gettext('Your export did not contain any data.')
                     )
                 file.filename, file.type, data = d
+
+                close_old_connections()  # This task can run very long, we might need a new DB connection
+
                 f = ContentFile(data)
                 file.file.save(cachedfile_name(file, file.filename), f)
     return str(file.pk)
@@ -154,6 +157,9 @@ def multiexport(self, organizer: Organizer, user: User, device: int, token: int,
                         gettext('Your export did not contain any data.')
                     )
                 file.filename, file.type, data = d
+
+                close_old_connections()  # This task can run very long, we might need a new DB connection
+
                 f = ContentFile(data)
                 file.file.save(cachedfile_name(file, file.filename), f)
     return str(file.pk)
@@ -214,6 +220,9 @@ def _run_scheduled_export(schedule, context: Union[Event, Organizer], exporter,
                 raise ExportError(
                     gettext('Your exported data exceeded the size limit for scheduled exports.')
                 )
+
+            close_old_connections()  # This task can run very long, we might need a new DB connection
+
             f = ContentFile(data)
             file.file.save(cachedfile_name(file, file.filename), f)
         except ExportEmptyError as e: