Jump to solution
Verify

urllib3 flaky and pytest-memray incompatible (Fix)

Fixed
Spec
Package
urllib3
Fixed In
1.26.13
Python
3.11
Verdict
Status
Fixed
Safe for prod
No
Risk
Medium
Last verified
2026-02-09
Own content ratio
0.34
#2830 ai connection-leak memory-leak retries timeouts Updated: 2026-02-13
Issue #2830

The Fix

pip install urllib3==1.26.13

Based on closed urllib3/urllib3 issue #2830 · PR/commit linked

Production note: Watch p95/p99 latency and retry volume; timeouts can turn into retry storms and duplicate side-effects.

Jump to Verify Open PR/Commit
@@ -9,4 +9,4 @@ trustme==0.9.0 backports.zoneinfo==0.2.1;python_version<"3.9" towncrier==21.9.0 -pytest-memray==1.3.0;python_version>="3.8" and sys_platform!="win32" and implementation_name=="cpython" +pytest-memray==1.3.1;python_version>="3.8" and sys_platform!="win32" and implementation_name=="cpython"
repro.py
===Flaky Test Report=== test_forwarding_proxy_request_timeout[https-https-True] failed (1 runs remaining out of 2). <class 'AssertionError'> assert <class 'urllib3.exceptions.ProxyError'> == ReadTimeoutError + where <class 'urllib3.exceptions.ProxyError'> = type(ProxyError('Unable to connect to proxy', ReadTimeoutError("HTTPSConnectionPool(host='240.0.0.0', port=443): Read timed out. (read timeout=0.01)"))) + where ProxyError('Unable to connect to proxy', ReadTimeoutError("HTTPSConnectionPool(host='240.0.0.0', port=443): Read timed out. (read timeout=0.01)")) = MaxRetryError('HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Max retries exceeded with url: https://240.0.0.0 (Caused by ProxyError(\'Unable to connect to proxy\', ReadTimeoutError("HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Read timed out. (read timeout=0.01)")))').reason + where MaxRetryError('HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Max retries exceeded with url: https://240.0.0.0 (Caused by ProxyError(\'Unable to connect to proxy\', ReadTimeoutError("HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Read timed out. (read timeout=0.01)")))') = <ExceptionInfo MaxRetryError('HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Max retries exceeded with url: https://240.0.0.0 (Ca...proxy\', ReadTimeoutError("HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Read timed out. (read timeout=0.01)")))') tblen=10>.value [<TracebackEntry /home/graingert/projects/urllib3/test/with_dummyserver/test_proxy_poolmanager.py:484>] test_forwarding_proxy_request_timeout[https-https-True] failed; it passed 0 out of the required 1 times. <class 'RuntimeError'> No more than one Tracker instance can be active at the same time [<TracebackEntry /home/graingert/projects/urllib3/.nox/test-3-11/lib/python3.11/site-packages/pytest_memray/plugin.py:122>, <TracebackEntry /home/graingert/projects/urllib3/.nox/test-3-11/lib/python3.11/site-packages/pytest_memray/plugin.py:121>, <TracebackEntry src/memray/_memray.pyx:404>]
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 urllib3==1.26.13\nWhen NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.\n\n

Why This Fix Works in Production

  • Trigger: ______________________________________________________________________________________________________…
  • Mechanism: Incompatibility between pytest-memray and flaky tests caused runtime errors
  • Why the fix works: Upgraded pytest-memray to fix incompatibility with flaky tests, resolving issue #2830. (first fixed release: 1.26.13).
Production impact:
  • If left unfixed, tail latency can spike under load and surface as timeouts/retries (amplifying incident impact).

Why This Breaks in Prod

  • Shows up under Python 3.11 in real deployments (not just unit tests).
  • Incompatibility between pytest-memray and flaky tests caused runtime errors
  • Surfaces as: ______________________________________________________________________________________________________ TestHTTPProxyManager.test_forwarding_proxy_request_timeout[https-https-True]…

Proof / Evidence

  • GitHub issue: #2830
  • Fix PR: https://github.com/urllib3/urllib3/pull/2832
  • First fixed release: 1.26.13
  • Reproduced locally: No (not executed)
  • Last verified: 2026-02-09
  • Confidence: 0.85
  • Did this fix it?: Yes (upstream fix exists)
  • Own content ratio: 0.34

Discussion

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

Jump to Sources Open on GitHub
“fixed in https://github.com/bloomberg/pytest-memray/pull/50”
@graingert · 2022-11-23 · confirmation · source

Failure Signature (Search String)

  • ______________________________________________________________________________________________________ TestHTTPProxyManager.test_forwarding_proxy_request_timeout[https-https-True]

Error Message

Stack trace
error.txt
Error Message ------------- ______________________________________________________________________________________________________ TestHTTPProxyManager.test_forwarding_proxy_request_timeout[https-https-True] ______________________________________________________________________________________________________ Traceback (most recent call last): File "/home/graingert/projects/urllib3/.nox/test-3-11/lib/python3.11/site-packages/pytest_memray/plugin.py", line 122, in wrapper result: object | None = func(*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^ File "/home/graingert/projects/urllib3/.nox/test-3-11/lib/python3.11/site-packages/pytest_memray/plugin.py", line 121, in wrapper with Tracker(result_file): File "src/memray/_memray.pyx", line 404, in memray._memray.Tracker.__enter__ RuntimeError: No more than one Tracker instance can be active at the same time

Minimal Reproduction

repro.py
===Flaky Test Report=== test_forwarding_proxy_request_timeout[https-https-True] failed (1 runs remaining out of 2). <class 'AssertionError'> assert <class 'urllib3.exceptions.ProxyError'> == ReadTimeoutError + where <class 'urllib3.exceptions.ProxyError'> = type(ProxyError('Unable to connect to proxy', ReadTimeoutError("HTTPSConnectionPool(host='240.0.0.0', port=443): Read timed out. (read timeout=0.01)"))) + where ProxyError('Unable to connect to proxy', ReadTimeoutError("HTTPSConnectionPool(host='240.0.0.0', port=443): Read timed out. (read timeout=0.01)")) = MaxRetryError('HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Max retries exceeded with url: https://240.0.0.0 (Caused by ProxyError(\'Unable to connect to proxy\', ReadTimeoutError("HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Read timed out. (read timeout=0.01)")))').reason + where MaxRetryError('HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Max retries exceeded with url: https://240.0.0.0 (Caused by ProxyError(\'Unable to connect to proxy\', ReadTimeoutError("HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Read timed out. (read timeout=0.01)")))') = <ExceptionInfo MaxRetryError('HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Max retries exceeded with url: https://240.0.0.0 (Ca...proxy\', ReadTimeoutError("HTTPSConnectionPool(host=\'240.0.0.0\', port=443): Read timed out. (read timeout=0.01)")))') tblen=10>.value [<TracebackEntry /home/graingert/projects/urllib3/test/with_dummyserver/test_proxy_poolmanager.py:484>] test_forwarding_proxy_request_timeout[https-https-True] failed; it passed 0 out of the required 1 times. <class 'RuntimeError'> No more than one Tracker instance can be active at the same time [<TracebackEntry /home/graingert/projects/urllib3/.nox/test-3-11/lib/python3.11/site-packages/pytest_memray/plugin.py:122>, <TracebackEntry /home/graingert/projects/urllib3/.nox/test-3-11/lib/python3.11/site-packages/pytest_memray/plugin.py:121>, <TracebackEntry src/memray/_memray.pyx:404>]

Environment

  • Python: 3.11

What Broke

Flaky tests resulted in inconsistent test failures and runtime errors.

Why It Broke

Incompatibility between pytest-memray and flaky tests caused runtime errors

Fix Options (Details)

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

pip install urllib3==1.26.13

When NOT to use: Do not use if it changes public behavior or if the failure cannot be reproduced.

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

Fix reference: https://github.com/urllib3/urllib3/pull/2832

First fixed release: 1.26.13

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

Get updates

We publish verified fixes weekly. No spam.

Subscribe

When NOT to Use This Fix

  • Do not use if it changes public behavior or if the failure cannot be reproduced.

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 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

VersionStatus
1.26.13 Fixed

Related Issues

No related fixes found.

Cluster: urllib3:timeout urllib3 hub urllib3 best practices All hubs All clusters
Related clusters: Configuration error Data consistency SSL handshake

Sources

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

Source & Disclaimer: Analysis derived from GitHub Issue #2830. Not affiliated with the library maintainers. Verify before production use.