Celery CELERY_DB_REUSE_MAX possibly broken by #6134 (Fix)

The Fix

pip install celery==4.4.4

Based on closed celery/celery issue #6216 · PR/commit linked

Production note: This usually shows up under retries/timeouts. Treat it as a side-effect risk until you can verify behavior with a canary + real traffic.

Jump to Verify Open PR/Commit

@@ -151,7 +151,7 @@ def on_worker_process_init(self, **kwargs):
 
         # use the _ version to avoid DB_REUSE preventing the conn.close() call
-        self._close_database()
+        self._close_database(force=True)
         self.close_cache()

repro

this bug.

verify

Follow the reproduction steps, confirm the failure, apply the fix, and repeat the same steps to verify the behavior changes.

fix.md

Option A — Upgrade to fixed release\npip install celery==4.4.4\nWhen NOT to use: This fix should not be applied if the application relies on the previous connection handling behavior.\n\n

Why This Fix Works in Production

Trigger: CELERY_DB_REUSE_MAX possibly broken by #6134
Mechanism: The handling of database connections was not properly closing after forking due to changes in #6134
Why the fix works: Fixes the handling of database connections in Celery by ensuring they are properly closed after forking, addressing potential issues with the CELERY_DB_REUSE_MAX setting. (first fixed release: 4.4.4).

Production impact:

If left unfixed, retries/timeouts can trigger duplicate external side-effects (double charges, duplicate emails, repeated writes).

Why This Breaks in Prod

The handling of database connections was not properly closing after forking due to changes in #6134
Production symptom (often without a traceback): CELERY_DB_REUSE_MAX possibly broken by #6134

Proof / Evidence

GitHub issue: #6216
Fix PR: https://github.com/celery/celery/pull/6134
First fixed release: 4.4.4
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.78

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“Makes sense to me. I didn't know about CELERY_DB_REUSE_MAX earlier; I can’t find it in documentation expect from the changelog of version 1.0.2 . It…”

@whtsky · 2020-07-08 · source

“@thedrow > You haven't provided the necessary debugging information and you didn't describe the actual behavior”

@thomas-riccardi · 2020-07-31 · source

Failure Signature (Search String)

CELERY_DB_REUSE_MAX possibly broken by #6134
- [x] I have included all related issues and possible duplicate issues

Copy-friendly signature

signature.txt

Failure Signature
-----------------
CELERY_DB_REUSE_MAX possibly broken by #6134
- [x] I have included all related issues and possible duplicate issues

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
CELERY_DB_REUSE_MAX possibly broken by #6134
- [x] I have included all related issues and possible duplicate issues

Minimal Reproduction

this bug.

What Broke

Potential database connection issues could arise, affecting task execution reliability.

Why It Broke

The handling of database connections was not properly closing after forking due to changes in #6134

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

pip install celery==4.4.4

When NOT to use: This fix should not be applied if the application relies on the previous connection handling behavior.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Fix reference: https://github.com/celery/celery/pull/6134

First fixed release: 4.4.4

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

This fix should not be applied if the application relies on the previous connection handling behavior.

Verify Fix

verify

Follow the reproduction steps, confirm the failure, apply the fix, and repeat the same steps to verify the behavior changes.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Capture the exact failing error string in logs and tests so you can reproduce via a minimal script.
Pin production dependencies and upgrade only with a reproducible test that hits the failing path.

Version Compatibility Table

Version	Status
4.4.4	Fixed

Related Issues

No related fixes found.

Cluster: celery:duplicates Celery hub Celery best practices All hubs All clusters

Related clusters: Configuration error Data consistency Duplicate processing

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.