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Support celerycam for reconnecting db connenction if db connection is lost accidentally #550

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17 changes: 14 additions & 3 deletions djcelery/snapshot.py
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@
from datetime import timedelta

from django.conf import settings
from django.db import connection
from django.db.utils import InterfaceError

from celery import states
from celery.events.state import Task
Expand Down Expand Up @@ -127,9 +129,18 @@ def _handle_tasks():
for i, task in enumerate(state.tasks.items()):
self.handle_task(task)

for worker in state.workers.items():
self.handle_worker(worker)
_handle_tasks()
try:
for worker in state.workers.items():
self.handle_worker(worker)
_handle_tasks()
except InterfaceError as e:
# When connection already closed exception is raised,
# force to close connection and Django will automatically reconnect
if str(e) == 'connection already closed':
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Copilot AI May 13, 2025

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Comparing exception message strings is brittle; consider catching a more specific exception subclass or inspecting error attributes instead of matching on str(e).

Suggested change
if str(e) == 'connection already closed':
if getattr(e, 'args', None) and 'connection already closed' in e.args[0]:

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connection.close()
Comment on lines +132 to +140
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Copilot AI May 13, 2025

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The try/except block wraps both worker and task handling, which may swallow unrelated errors. Consider narrowing the scope to only the database operations that need reconnection.

Suggested change
try:
for worker in state.workers.items():
self.handle_worker(worker)
_handle_tasks()
except InterfaceError as e:
# When connection already closed exception is raised,
# force to close connection and Django will automatically reconnect
if str(e) == 'connection already closed':
connection.close()
for worker in state.workers.items():
self.handle_worker(worker)
_handle_tasks()
try:
# Check and handle database reconnection if needed
connection.close()
except InterfaceError as e:
# When connection already closed exception is raised,
# force to close connection and Django will automatically reconnect
if str(e) == 'connection already closed':

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logger.info(
'Django db connection is closed and will reconnect'
)

def on_cleanup(self):
expired = (self.TaskState.objects.expire_by_states(states, expires)
Expand Down