The Fix
Upgrade to version 0.13.0 or later.
Based on closed encode/httpx issue #34 · PR/commit linked
Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.
@@ -242,6 +242,10 @@ async def open_uds_stream(
return SocketStream(stream_reader=stream_reader, stream_writer=stream_writer)
+ def time(self) -> float:
+ loop = asyncio.get_event_loop()
+ return loop.time()
Option A — Upgrade to fixed release\nUpgrade to version 0.13.0 or later.\nWhen NOT to use: This fix should not be used if the application requires persistent connections beyond the timeout.\n\n
Why This Fix Works in Production
- Trigger: Keep-Alive timeouts
- Mechanism: Keep-Alive connections were not automatically closed after a timeout period
- Why the fix works: Implements keep-alive timeouts for connections, automatically closing them after a specified timeout period. (first fixed release: 0.13.0).
- If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.
Why This Breaks in Prod
- Keep-Alive connections were not automatically closed after a timeout period
- Production symptom (often without a traceback): Keep-Alive timeouts
Proof / Evidence
- GitHub issue: #34
- Fix PR: https://github.com/encode/httpx/pull/627
- First fixed release: 0.13.0
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.85
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.79
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“Actually for robustness, this really *is* required. * asyncio has futzy connected-ness testing. #95 * If a server sends a 408 timeout response, then we'll…”
“Actually I don't have any issue with the behavior that our ConnectionPool currently has”
Failure Signature (Search String)
- Keep-Alive timeouts
- We should automatically close any Keep-Alive connections after a timeout period.
Copy-friendly signature
Failure Signature
-----------------
Keep-Alive timeouts
We should automatically close any Keep-Alive connections after a timeout period.
Error Message
Signature-only (no traceback captured)
Error Message
-------------
Keep-Alive timeouts
We should automatically close any Keep-Alive connections after a timeout period.
What Broke
Connections remained open indefinitely, potentially leading to resource exhaustion.
Why It Broke
Keep-Alive connections were not automatically closed after a timeout period
Fix Options (Details)
Option A — Upgrade to fixed release Safe default (recommended)
Upgrade to version 0.13.0 or later.
Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.
Fix reference: https://github.com/encode/httpx/pull/627
First fixed release: 0.13.0
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix should not be used if the application requires persistent connections beyond the timeout.
Did This Fix Work in Your Case?
Quick signal helps us prioritize which fixes to verify and improve.
Prevention
- Add a CI check that diffs key outputs after upgrades (OpenAPI schema snapshots, JSON payload shapes, CLI output).
- Upgrade behind a canary and run integration tests against the canary before 100% rollout.
- 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 |
|---|---|
| 0.13.0 | Fixed |
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.