redis-py Connection is not thread-safe (Fix)

The Fix

pip install redis==7.1.0

Based on closed redis/redis-py issue #1178 · PR/commit linked

Open PR/Commit

@@ -20,6 +20,14 @@
     * Slightly optimized command packing. Thanks @Deneby67. #1255
     * Added support for the TYPE argument to SCAN. Thanks @netocp. #1220
+    * Better thread and fork safety in ConnectionPool and
+      BlockingConnectionPool. Added better locking to synchronize critical
+      sections rather than relying on CPython-specific implementation details

fix.md

Option A — Upgrade to fixed release\npip install redis==7.1.0\nWhen NOT to use: This fix should not be applied if the application relies on non-thread-safe connections intentionally.\n\n

Why This Fix Works in Production

Trigger: So when one thread in on_connect() call `read_response`, it maybe get another thread's response, then raise the error.
Mechanism: Connection class lacks thread safety, leading to potential data corruption when accessed by multiple threads
Why the fix works: Implements better thread safety for ConnectionPool, addressing the issue of thread safety in connections. (first fixed release: 7.1.0).

Production impact:

If left unfixed, this can cause silent data inconsistencies that propagate (bad cache entries, incorrect downstream decisions).

Why This Breaks in Prod

Shows up under Python 3.7 in real deployments (not just unit tests).
Connection class lacks thread safety, leading to potential data corruption when accessed by multiple threads
Production symptom (often without a traceback): So when one thread in on_connect() call `read_response`, it maybe get another thread's response, then raise the error.

Proof / Evidence

GitHub issue: #1178
Fix PR: https://github.com/redis/redis-py/pull/1270
First fixed release: 7.1.0
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.85
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.69

Discussion

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

Jump to Sources Open on GitHub

“Connections are not meant to be threadsafe. ConnectionPools are threadsafe.”

@andymccurdy · 2019-06-20 · source

“@andymccurdy https://github.com/andymccurdy/redis-py/issues/906 it seems the default connectionpool is not threading safe.”

@wynemo · 2019-11-04 · source

Failure Signature (Search String)

So when one thread in on_connect() call `read_response`, it maybe get another thread's response, then raise the error.
raise AuthenticationError('Invalid Password')

Copy-friendly signature

signature.txt

Failure Signature
-----------------
So when one thread in on_connect() call  `read_response`, it maybe get another thread's response, then raise the error.
raise AuthenticationError('Invalid Password')

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
So when one thread in on_connect() call  `read_response`, it maybe get another thread's response, then raise the error.
raise AuthenticationError('Invalid Password')

Environment

Python: 3.7

What Broke

Threads may receive incorrect responses, causing unexpected errors and application instability.

Why It Broke

Connection class lacks thread safety, leading to potential data corruption when accessed by multiple threads

Fix Options (Details)

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

pip install redis==7.1.0

When NOT to use: This fix should not be applied if the application relies on non-thread-safe connections intentionally.

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

Fix reference: https://github.com/redis/redis-py/pull/1270

First fixed release: 7.1.0

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 non-thread-safe connections intentionally.

Did This Fix Work in Your Case?

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

Prevention

Track RSS + object counts after deployments; alert on monotonic growth and GC pressure.
Add a long-running test that repeats the failing call path and asserts stable memory.

Version Compatibility Table

Version	Status
7.1.0	Fixed

Related Issues

No related fixes found.

Cluster: redis-py:data-consistency redis-py hub redis-py best practices All hubs All clusters

Related clusters: Configuration error Retry storm Race condition

Sources

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