fix: scope AsyncFastAPI HTTP client pool to instance instead of class

[YizukiAme]

Fixes #6869

Problem

AsyncFastAPI._clients is declared as a class variable, so all instances share the same Dict[int, httpx.AsyncClient] pool. When multiple AsyncFastAPI instances are created (e.g. in tests or multi-tenant setups), they cross-contaminate each other's HTTP transports. Closing one instance's client can corrupt another instance's connection pool.

Fix

Move _clients initialization from class-level to __init__, making it an instance variable:

-_clients: Dict[int, httpx.AsyncClient] = {}
-
 def __init__(self, system: System):
     super().__init__(system)
+    self._clients: Dict[int, httpx.AsyncClient] = {}

Tests

53-line test verifying that two AsyncFastAPI instances maintain independent client pools and that cleanup of one does not affect the other.

This fix was developed with AI assistance and reviewed by a human.

[github-actions]

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Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
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[propel-code-bot]

Fix AsyncFastAPI client pool scoping to prevent cross-instance transport sharing

This PR fixes a bug where AsyncFastAPI used a class-level _clients dictionary, causing all instances to share the same event-loop-keyed httpx.AsyncClient pool. The change moves _clients initialization into AsyncFastAPI.__init__, making the pool instance-scoped and preventing one instance’s cleanup from closing another instance’s client.

A focused test is added to verify isolation between two AsyncFastAPI instances: each creates its own client, cleanup on one instance only closes its own client, and the second instance continues reusing its existing client until it is explicitly cleaned up.

This summary was automatically generated by @propel-code-bot

[propel-code-bot]

No issues were identified; the instance-scoped client pool fix and isolation test appear sound.

Status: No Issues Found | Risk: Low

Review Details

📁 2 files reviewed | 💬 0 comments