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Fix: avoid uncessary retries in OAuth authenticated requests #1206
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Hi @keurcien, thanks for this PR!
I wonder if you could add a test case, maybe in tests/client/test_auth.py, based on your snippet? (if it's not too involved)
Sure, will do this week if I find some time |
This test validates the fix for PR #1206 which resolved a critical performance issue where every request was being sent twice due to incorrect indentation of retry logic. The test: - Simulates a successful authenticated request (200 response) - Counts how many times the request is yielded - FAILS with buggy version: 2 yields (double sending) - PASSES with fix: 1 yield (correct behavior) This directly tests the root cause that made OAuth requests 2x slower and ensures this regression cannot occur again.
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This test validates the fix for PR modelcontextprotocol#1206 which resolved a critical performance issue where every request was being sent twice due to incorrect indentation of retry logic. The test: - Simulates a successful authenticated request (200 response) - Counts how many times the request is yielded - FAILS with buggy version: 2 yields (double sending) - PASSES with fix: 1 yield (correct behavior) This directly tests the root cause that made OAuth requests 2x slower and ensures this regression cannot occur again.
Add missing type hints to test_auth_flow_no_unnecessary_retry_after_oauth to satisfy pyright type checking requirements.
The retry logic fix in PR-1206 moved the final request yield inside the OAuth flow block, which now correctly retries requests after OAuth completion. However, the existing tests didn't expect this final yield and would exit the generator early, causing a GeneratorExit exception while the async lock was still held. This resulted in RuntimeError: The current task is not holding this lock. Fix by properly closing the generators in both failing tests: - test_oauth_discovery_fallback_conditions - test_auth_flow_with_no_tokens Both tests now send a final success response to properly complete the auth flow generator and prevent the lock release error.
await auth_flow.asend(final_response) | ||
except StopAsyncIteration: | ||
pass # Expected - generator should complete | ||
|
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These tests were inadvertently tuned to the buggy behavior where requests were being unconditionally retried after every response. The indentation fix ensures retries only happen after OAuth completion (401 responses), not after successful responses. This exposed that the tests weren't properly closing the auth flow generator after the legitimate OAuth retry, causing lock release errors.
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Thanks @felixweinberger for the test updates!
This fix also resolves a timeout issue when using stored access tokens in SSE auth flow (happened as soon as I replaced InMemoryTokenStorage with a keychain-based token storage). |
* Add regression test for stateless request memory cleanup (modelcontextprotocol#1140) * Implement RFC9728 - Support WWW-Authenticate header by MCP client (modelcontextprotocol#1071) * Add streamable HTTP starlette example to Python SDK docs (modelcontextprotocol#1111) * fix markdown error in README in main (modelcontextprotocol#1147) * README - replace code snippets with examples - add lowlevel to snippets (modelcontextprotocol#1150) * README - replace code snippets with examples - streamable http (modelcontextprotocol#1155) * chore: don't allow users to create issues outside the templates (modelcontextprotocol#1163) * Tests(cli): Add coverage for helper functions (modelcontextprotocol#635) * Docs: Update CallToolResult parsing in README (modelcontextprotocol#812) Co-authored-by: Felix Weinberger <[email protected]> * docs: add pre-commit install guide on CONTRIBUTING.md (modelcontextprotocol#995) Co-authored-by: Felix Weinberger <[email protected]> * fix flaky fix-test_streamablehttp_client_resumption test (modelcontextprotocol#1166) * README - replace code snippets with examples -- auth examples (modelcontextprotocol#1164) * Support falling back to OIDC metadata for auth (modelcontextprotocol#1061) * Add CODEOWNERS file for sdk (modelcontextprotocol#1169) * fix flaky test test_88_random_error (modelcontextprotocol#1171) * Make sure `RequestId` is not coerced as `int` (modelcontextprotocol#1178) * Fix: Replace threading.Lock with anyio.Lock for Ray deployment compatibility (modelcontextprotocol#1151) * fix: fix OAuth flow request object handling (modelcontextprotocol#1174) * update codeowners group (modelcontextprotocol#1191) * fix: perform auth server metadata discovery fallbacks on any 4xx (modelcontextprotocol#1193) * server: skip duplicate response on CancelledError (modelcontextprotocol#1153) Co-authored-by: ihrpr <[email protected]> * Unpack settings in FastMCP (modelcontextprotocol#1198) * chore: Remove unused prompt_manager.py file (modelcontextprotocol#1229) Co-authored-by: Tapan Chugh <[email protected]> * Improved supported for ProtectedResourceMetadata (modelcontextprotocol#1235) Co-authored-by: Paul Carleton <[email protected]> * chore: Remove unused variable notification_options (modelcontextprotocol#1238) * Improve README around the Context object (modelcontextprotocol#1203) * fix: allow to pass `list[str]` to `token_endpoint_auth_signing_alg_values_supported` (modelcontextprotocol#1226) * Remove strict validation on `response_modes_supported` member of `OAuthMetadata` (modelcontextprotocol#1243) * Add pyright strict mode on the whole project (modelcontextprotocol#1254) * Consistent casing for default headers Accept and Content-Type (modelcontextprotocol#1263) * Update dependencies and fix type issues (modelcontextprotocol#1268) Co-authored-by: Marcelo Trylesinski <[email protected]> * fix: prevent async generator cleanup errors in StreamableHTTP transport (modelcontextprotocol#1271) Co-authored-by: David Soria Parra <[email protected]> * chore: uncomment .idea/ in .gitignore (modelcontextprotocol#1287) Co-authored-by: Claude <[email protected]> * docs: clarify streamable_http_path configuration when mounting servers (modelcontextprotocol#1172) * feat: Add CORS configuration for browser-based MCP clients (modelcontextprotocol#1059) Co-authored-by: Marcelo Trylesinski <[email protected]> Co-authored-by: Felix Weinberger <[email protected]> * Added Audio to FastMCP (modelcontextprotocol#1130) * fix: avoid uncessary retries in OAuth authenticated requests (modelcontextprotocol#1206) Co-authored-by: Felix Weinberger <[email protected]> * Add PATHEXT to default STDIO env vars in windows (modelcontextprotocol#1256) * fix: error too many values to unpack (expected 2) (modelcontextprotocol#1279) Signed-off-by: San Nguyen <[email protected]> Co-authored-by: Felix Weinberger <[email protected]> Co-authored-by: Felix Weinberger <[email protected]> * SDK Parity: Avoid Parsing Server Response for non-JsonRPCMessage Requests (modelcontextprotocol#1290) * types: Setting default value for method: Literal (modelcontextprotocol#1292) * changes structured temperature to not deadly (modelcontextprotocol#1328) * Update simple-resource example to use non-deprecated read_resource return type (modelcontextprotocol#1331) Co-authored-by: Claude <[email protected]> * docs: Update README to include link to API docs for modelcontextprotocol#1329 (modelcontextprotocol#1330) * Allow ping requests before initialization (modelcontextprotocol#1312) * Python lint: Ruff rules for pylint and code complexity (modelcontextprotocol#525) * Fix context injection for resources and prompts (modelcontextprotocol#1336) * fix(fastmcp): propagate mimeType in resource template list (modelcontextprotocol#1186) Co-authored-by: Felix Weinberger <[email protected]> * fix: allow elicitations accepted without content (modelcontextprotocol#1285) Co-authored-by: Olivier Schiavo <[email protected]> * Use --frozen in pre-commit config (modelcontextprotocol#1375) * Return HTTP 403 for invalid Origin headers (modelcontextprotocol#1353) * Add test for ProtectedResourceMetadataParsing (modelcontextprotocol#1236) Co-authored-by: Paul Carleton <[email protected]> Co-authored-by: Marcelo Trylesinski <[email protected]> Co-authored-by: Felix Weinberger <[email protected]> * Fastmcp logging progress example (modelcontextprotocol#1270) Co-authored-by: Felix Weinberger <[email protected]> * feat: add paginated list decorators for prompts, resources, and tools (modelcontextprotocol#1286) Co-authored-by: Claude <[email protected]> * Remove "unconditionally" from conditional description (modelcontextprotocol#1289) * Use streamable-http consistently in examples (modelcontextprotocol#1389) * feat: Add SDK support for SEP-1034 default values in elicitation schemas (modelcontextprotocol#1337) Co-authored-by: Tapan Chugh <[email protected]> Co-authored-by: Felix Weinberger <[email protected]> * Implementation of SEP 973 - Additional metadata + icons support (modelcontextprotocol#1357) * Merge upstream/main with custom filtering --------- Signed-off-by: San Nguyen <[email protected]> Co-authored-by: Felix Weinberger <[email protected]> Co-authored-by: yurikunash <[email protected]> Co-authored-by: Pamela Fox <[email protected]> Co-authored-by: Inna Harper <[email protected]> Co-authored-by: Marcelo Trylesinski <[email protected]> Co-authored-by: Ian Davenport <[email protected]> Co-authored-by: Dagang Wei <[email protected]> Co-authored-by: Felix Weinberger <[email protected]> Co-authored-by: Stanley Law <[email protected]> Co-authored-by: Luca Chang <[email protected]> Co-authored-by: leweng <[email protected]> Co-authored-by: Clare Liguori <[email protected]> Co-authored-by: lukacf <[email protected]> Co-authored-by: ihrpr <[email protected]> Co-authored-by: Tapan Chugh <[email protected]> Co-authored-by: Tapan Chugh <[email protected]> Co-authored-by: Yann Jouanin <[email protected]> Co-authored-by: Paul Carleton <[email protected]> Co-authored-by: Sreenath Somarajapuram <[email protected]> Co-authored-by: Omer Korner <[email protected]> Co-authored-by: joesavage-silabs <[email protected]> Co-authored-by: Gregory L <[email protected]> Co-authored-by: David Soria Parra <[email protected]> Co-authored-by: Moustapha Ebnou <[email protected]> Co-authored-by: Max Isbey <[email protected]> Co-authored-by: Claude <[email protected]> Co-authored-by: Jerome <[email protected]> Co-authored-by: xavier <[email protected]> Co-authored-by: keurcien <[email protected]> Co-authored-by: Tim Esler <[email protected]> Co-authored-by: San Nguyen <[email protected]> Co-authored-by: Justin Wang <[email protected]> Co-authored-by: jess <[email protected]> Co-authored-by: Peter Alexander <[email protected]> Co-authored-by: Reid Geyer <[email protected]> Co-authored-by: Eleftheria Stein-Kousathana <[email protected]> Co-authored-by: Christian Clauss <[email protected]> Co-authored-by: pchoudhury22 <[email protected]> Co-authored-by: owengo <[email protected]> Co-authored-by: Olivier Schiavo <[email protected]> Co-authored-by: Steve Billings <[email protected]> Co-authored-by: Mike Salvatore <[email protected]>
Motivation and Context
Tried to connect an MCP client to Notion's MCP client (more info here: #1204)
How Has This Been Tested?
Using a local script wrapping this code snippet:
Now
list_tools()
,list_resources()
andcall_tool()
run instantly.Breaking Changes
No
Types of changes
Checklist
Additional context