redis-py Connection task cancel doesn't clean up and hangs

The Fix

pip install redis==7.1.0

Based on closed redis/redis-py issue #2511 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -502,8 +502,6 @@ async def read_from_socket(
             # return True to indicate that data was read.
             return True
-        except asyncio.CancelledError:
-            raise
         except (socket.timeout, asyncio.TimeoutError):

repro.py

Traceback (most recent call last):
  File "/usr/lib/python3.10/unittest/async_case.py", line 67, in _callTearDown
    self._callAsync(self.asyncTearDown)
  File "/usr/lib/python3.10/unittest/async_case.py", line 79, in _callAsync
    return self._asyncioTestLoop.run_until_complete(fut)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
    return future.result()
  File "/usr/lib/python3.10/unittest/async_case.py", line 101, in _asyncioLoopRunner
    ret = await awaitable
  File "/home/toby/dev/saq/tests/test_worker.py", line 64, in asyncTearDown
    await cleanup_queue(self.queue)
  File "/home/toby/dev/saq/tests/helpers.py", line 11, in cleanup_queue
    await queue.redis.flushdb()
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 487, in execute_command
    return await conn.retry.call_with_retry(
  File "/home/toby/dev/redis-py/redis/asyncio/retry.py", line 62, in call_with_retry
    await fail(error)
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 476, in _disconnect_raise
    raise error
  File "/home/toby/dev/redis-py/redis/asyncio/retry.py", line 59, in call_with_retry
    return await do()
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 463, in _send_command_parse_response
    return await self.parse_response(conn, command_name, **options)
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 505, in parse_response
    response = await connection.read_response()
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 948, in read_response
    response = await self._parser.read_response(
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 397, in read_response
    raw = await self._buffer.readline()
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 323, in readline
    await self._read_from_socket()
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 266, in _read_from_socket
    raise ConnectionError(SERVER_CLOSED_CONNECTION_ERROR)
redis.exceptions.ConnectionError: Connection closed by server.

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: This fix should not be applied if the application relies on handling BaseException specifically.\n\n

Why This Fix Works in Production

Trigger: self._callAsync(self.asyncTearDown)
Mechanism: The change in exception handling from BaseException to Exception caused unit tests to hang indefinitely
Why the fix works: Addresses the issue by changing the exception handling in the Connection class from BaseException to Exception, preventing unit tests from hanging. (first fixed release: 7.1.0).

Why This Breaks in Prod

Shows up under Python 3.5.1 in real deployments (not just unit tests).
The change in exception handling from BaseException to Exception caused unit tests to hang indefinitely
Surfaces as: Traceback (most recent call last):

Proof / Evidence

GitHub issue: #2511
Fix PR: https://github.com/redis/redis-py/pull/2104
First fixed release: 7.1.0
Reproduced locally: No (not executed)
Last verified: 2026-02-07
Confidence: 0.75
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.28

Discussion

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

Jump to Sources Open on GitHub

“Closing as I assume this issue was fixed with all the async and CancelledError fixes. @tobymao Feel free to re-open it if this still happen…”

@dvora-h · 2023-07-16 · confirmation · source

“after doing some more research, it looks like there was a lengthy discussion about it https://github.com/redis/redis-py/issues/2103 as noted, my unit test shows that redis is…”

@tobymao · 2022-12-14 · source

Failure Signature (Search String)

self._callAsync(self.asyncTearDown)

Error Message

Stack trace

error.txt

Error Message
-------------
Traceback (most recent call last):
  File "/usr/lib/python3.10/unittest/async_case.py", line 67, in _callTearDown
    self._callAsync(self.asyncTearDown)
  File "/usr/lib/python3.10/unittest/async_case.py", line 79, in _callAsync
    return self._asyncioTestLoop.run_until_complete(fut)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
    return future.result()
  File "/usr/lib/python3.10/unittest/async_case.py", line 101, in _asyncioLoopRunner
    ret = await awaitable
  File "/home/toby/dev/saq/tests/test_worker.py", line 64, in asyncTearDown
    await cleanup_queue(self.queue)
  File "/home/toby/dev/saq/tests/helpers.py", line 11, in cleanup_queue
    await queue.redis.flushdb()
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 487, in execute_command
    return await conn.retry.call_with_retry(
  File "/home/toby/dev/redis-py/redis/asyncio/retry.py", line 62, in call_with_retry
    await fail(error)
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 476, in _disconnect_raise
    raise error
  File "/home/toby/dev/redis-py/redis/asyncio/retry.py", line 59, in call_with_retry
    return await do()
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 463, in _send_command_parse_response
    return await self.parse_response(conn, command_name, **options)
  File "/home/toby/dev/redis-py/redis/asyncio/client.py
... (truncated) ...

Minimal Reproduction

repro.py

Traceback (most recent call last):
  File "/usr/lib/python3.10/unittest/async_case.py", line 67, in _callTearDown
    self._callAsync(self.asyncTearDown)
  File "/usr/lib/python3.10/unittest/async_case.py", line 79, in _callAsync
    return self._asyncioTestLoop.run_until_complete(fut)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
    return future.result()
  File "/usr/lib/python3.10/unittest/async_case.py", line 101, in _asyncioLoopRunner
    ret = await awaitable
  File "/home/toby/dev/saq/tests/test_worker.py", line 64, in asyncTearDown
    await cleanup_queue(self.queue)
  File "/home/toby/dev/saq/tests/helpers.py", line 11, in cleanup_queue
    await queue.redis.flushdb()
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 487, in execute_command
    return await conn.retry.call_with_retry(
  File "/home/toby/dev/redis-py/redis/asyncio/retry.py", line 62, in call_with_retry
    await fail(error)
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 476, in _disconnect_raise
    raise error
  File "/home/toby/dev/redis-py/redis/asyncio/retry.py", line 59, in call_with_retry
    return await do()
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 463, in _send_command_parse_response
    return await self.parse_response(conn, command_name, **options)
  File "/home/toby/dev/redis-py/redis/asyncio/client.py", line 505, in parse_response
    response = await connection.read_response()
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 948, in read_response
    response = await self._parser.read_response(
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 397, in read_response
    raw = await self._buffer.readline()
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 323, in readline
    await self._read_from_socket()
  File "/home/toby/dev/redis-py/redis/asyncio/connection.py", line 266, in _read_from_socket
    raise ConnectionError(SERVER_CLOSED_CONNECTION_ERROR)
redis.exceptions.ConnectionError: Connection closed by server.

Environment

Python: 3.5.1

What Broke

Unit tests hang forever, requiring termination of Redis to stop the process.

Why It Broke

The change in exception handling from BaseException to Exception caused unit tests to hang indefinitely

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 handling BaseException specifically.

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/2104

First fixed release: 7.1.0

Last verified: 2026-02-07. Validate in your environment.

When NOT to Use This Fix

This fix should not be applied if the application relies on handling BaseException specifically.

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

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
7.1.0	Fixed

Related Issues

No related fixes found.

Cluster: redis-py:queues redis-py hub redis-py best practices All hubs All clusters

Related clusters: Configuration error Retry storm Data consistency

Sources

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

redis-py Connection task cancel doesn't clean up and hangs (Fix)