The Fix
pip install redis==7.1.0
Based on closed redis/redis-py issue #1740 · PR/commit linked
Production note: This tends to surface only under concurrency. Reproduce with load tests and watch for lock contention/cancellation paths.
@@ -1276,18 +1276,17 @@ def __init__(
self.ignore_subscribe_messages = ignore_subscribe_messages
self.connection = None
+ self.subscribed_event = threading.Event()
# we need to know the encoding options for this connection in order
# to lookup channel and pattern names for callback handlers.
repro.py
#!/usr/bin/env python3
import threading
import time
import redis
def poll(ps, event):
print(ps.get_message(timeout=5))
event.wait()
while True:
message = ps.get_message(timeout=5)
if message is not None:
print(message)
else:
break
def main():
r = redis.Redis.from_url("redis://localhost", health_check_interval=1)
ps = r.pubsub()
ps.subscribe("foo")
event = threading.Event()
poller = threading.Thread(target=poll, args=(ps, event))
poller.start()
time.sleep(2)
event.set()
ps.unsubscribe("foo")
poller.join()
main()
verify
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
fix.md
Option A — Upgrade to fixed release\npip install redis==7.1.0\nWhen NOT to use: Do not use this fix if the application relies on the previous behavior of health checks with active subscriptions.\n\n
Why This Fix Works in Production
- Trigger: redis.exceptions.ConnectionError: Bad response from PING health check because the response is b"redis-py-health-check" .
- Mechanism: Race condition occurs when get_message is called during an unsubscribe operation, leading to misinterpretation of health check responses
- Why the fix works: Fixes a race condition in health checks and pubsub by allowing get_message() to be called without prior subscription, preventing misinterpretation of health check responses. (first fixed release: 7.1.0).
Production impact:
- If left unfixed, failures can be intermittent under concurrency (hard to reproduce; shows up as sporadic 5xx/timeouts).
Why This Breaks in Prod
- Shows up under Python 3.8 in real deployments (not just unit tests).
- Race condition occurs when get_message is called during an unsubscribe operation, leading to misinterpretation of health check responses
- Surfaces as: redis.exceptions.ConnectionError: Bad response from PING health check\nbecause the response is b"redis-py-health-check" .
Proof / Evidence
- GitHub issue: #1740
- Fix PR: https://github.com/redis/redis-py/pull/1737
- First fixed release: 7.1.0
- Reproduced locally: No (not executed)
- Last verified: 2026-02-07
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.61
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“Hey @bmerry, I ran it over 30 minutes with the fix I posted in #1737 (there's a fresh new commit), and it didn't get reproduced.…”
“Thanks, I'll take a look when I can - but it will probably only be next week as I have some fires to put out…”
“Using this issue I found #1737 have a different error: If UNSUBSCRIBE response is received before the PING response received: in this case get_message will…”
Failure Signature (Search String)
- redis.exceptions.ConnectionError: Bad response from PING health check\nbecause the response is b"redis-py-health-check" .
Error Message
Stack trace
error.txt
Error Message
-------------
redis.exceptions.ConnectionError: Bad response from PING health check\nbecause the response is b"redis-py-health-check" .
Minimal Reproduction
repro.py
#!/usr/bin/env python3
import threading
import time
import redis
def poll(ps, event):
print(ps.get_message(timeout=5))
event.wait()
while True:
message = ps.get_message(timeout=5)
if message is not None:
print(message)
else:
break
def main():
r = redis.Redis.from_url("redis://localhost", health_check_interval=1)
ps = r.pubsub()
ps.subscribe("foo")
event = threading.Event()
poller = threading.Thread(target=poll, args=(ps, event))
poller.start()
time.sleep(2)
event.set()
ps.unsubscribe("foo")
poller.join()
main()
Environment
- Python: 3.8
What Broke
This causes incorrect responses during pubsub operations, potentially leading to application errors or unexpected behavior.
Why It Broke
Race condition occurs when get_message is called during an unsubscribe operation, leading to misinterpretation of health check responses
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
pip install redis==7.1.0
When NOT to use: Do not use this fix if the application relies on the previous behavior of health checks with active subscriptions.
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/1737
First fixed release: 7.1.0
Last verified: 2026-02-07. Validate in your environment.
When NOT to Use This Fix
- Do not use this fix if the application relies on the previous behavior of health checks with active subscriptions.
Verify Fix
verify
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
Did This Fix Work in Your Case?
Quick signal helps us prioritize which fixes to verify and improve.
Prevention
- Add a stress test that runs high-concurrency workloads and fails on thread dumps / blocked locks.
- Enable watchdog dumps in prod (faulthandler, thread dump endpoint) to capture deadlocks quickly.
- Make timeouts explicit and test them (unit + integration) to avoid silent behavior changes.
- Instrument retries (attempt count + reason) and alert on spikes to catch dependency slowdowns.
Version Compatibility Table
| Version | Status |
|---|---|
| 7.1.0 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.