fix: deduplicate urllib3 spans when PoolManager delegates to HTTPConnectionPool

[sohankshirsagar]

• merge main once this pr is merge test: enforce strict replay sandboxing in e2e fixtures #79

Summary

Urllib3Instrumentation patches both PoolManager.urlopen() and HTTPConnectionPool.urlopen() to cover two distinct user-facing entry paths. However, when a request goes through PoolManager, it internally delegates to HTTPConnectionPool.urlopen(), causing both patches to fire and producing two identical spans for a single HTTP request (a parent PoolManager span and a redundant child ConnectionPool span).

This fix introduces a ContextVar (_inside_poolmanager) that the PoolManager patch sets to True for the duration of its call. The ConnectionPool patch checks this flag and passes through without creating a span when it detects the request already originated from PoolManager. Direct HTTPConnectionPool usage (bypassing PoolManager) is unaffected since the flag remains False.

Changes

• Added _inside_poolmanager ContextVar to signal when a request is already being handled by the PoolManager patch
• Set the flag in _patch_pool_manager and reset it in the finally block (thread-safe and async-safe)
• Added early-exit check in _patch_connection_pool to skip span creation when inside a PoolManager call
• Extracted repeated passthrough argument lists in the ConnectionPool patch into a functools.partial (_passthrough) to reduce duplication across the three early-return paths (disabled, inside-poolmanager, higher-level instrumentation)

[tusk-dev]

Generated 11 tests - 11 passed

 

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Test Summary

• Urllib3Instrumentation._patch_connection_pool - 4 ✓
• Urllib3Instrumentation._patch_pool_manager - 3 ✓
• Urllib3Instrumentation._patch_pool_manager, Urllib3Instrumentation._patch_connection_pool - 1 ✓
• _inside_poolmanager - 3 ✓

Results

Tusk's tests all pass and validate the core deduplication fix. The ContextVar (_inside_poolmanager) is properly initialized, set/reset during PoolManager execution, and isolated across contexts—critical for thread-safety. The PoolManager patch correctly sets the flag and cleans up even on exceptions, while the ConnectionPool patch skips span creation when the flag is set but still instruments direct ConnectionPool calls. The integration test confirms the fix works end-to-end: a single request through PoolManager now produces one span instead of two. This directly addresses the duplicate span problem that was polluting traces and making debugging harder.

Key Points:

• _inside_poolmanager context isolation prevents state leaks across concurrent requests
• PoolManager patch reliably sets/resets the flag, including exception paths
• ConnectionPool patch correctly gates span creation based on the flag while preserving direct usage instrumentation
• Integration test validates the deduplication works in practice—no more redundant child spans

View check history

Commit	Status	Output	Created (UTC)
b1c3f69	Generated 11 tests - 11 passed	Tests	Mar 20, 2026 3:12AM
8d85236	Generated 11 tests - 11 passed	Tests	Mar 20, 2026 5:47PM

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[cubic-dev-ai]

No issues found across 1 file