You've already forked adk-python
mirror of
https://github.com/encounter/adk-python.git
synced 2026-03-30 10:57:20 -07:00
Kathy Wu
cce430da79
Merge https://github.com/google/adk-python/pull/4025 **Please ensure you have read the [contribution guide](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) before creating a pull request.** ### Link to Issue or Description of Change **1. Link to an existing issue (if applicable):** - Closes: - #3950 - #3731 - #3708 **2. Or, if no issue exists, describe the change:** **Problem:** - `ClientSession` of https://github.com/modelcontextprotocol/python-sdk uses AnyIO for async task management. - AnyIO TaskGroup requires its start and close must happen in a same task. - Since `McpSessionManager` does not create task per client, the client might be closed by different task, cause the error: `Attempted to exit cancel scope in a different task than it was entered in`. **Solution:** I Suggest 2 changes: Handling the `ClientSession` in a single task - To start and close `ClientSession` by the same task, we need to wrap the whole lifecycle of `ClientSession` to a single task. - `SessionContext` wraps the initialization and disposal of `ClientSession` to a single task, ensures that the `ClientSession` will be handled only in a dedicated task. Add timeout for `ClientSession` - Since now we are using task per `ClientSession`, task should never be leaked. - But `McpSessionManager` does not deliver timeout directly to `ClientSession` when the type is not STDIO. - There is only timeout for `httpx` client when MCP type is SSE or StreamableHTTP. - But the timeout applys only to `httpx` client, so if there is an issue in MCP client itself(e.g. https://github.com/modelcontextprotocol/python-sdk/issues/262), a tool call waits the result **FOREVER**! - To overcome this issue, I propagated the `sse_read_timeout` to `ClientSession`. - `timeout` is too short for timeout for tool call, since its default value is only 5s. - `sse_read_timeout` is originally made for read timeout of SSE(default value of 5m or 300s), but actually most of SSE implementations from server (e.g. FastAPI, etc.) sends ping periodically(about 15s I assume), so in a normal circumstances this timeout is quite useless. - If the server does not send ping, the timeout is equal to tool call timeout. Therefore, it would be appropriate to use `sse_read_timeout` as tool call timeout. - Most of tool calls should finish within 5 minutes, and sse timeout is adjustable if not. - If this change is not acceptable, we could make a dedicate parameter for tool call timeout(e.g. `tool_call_timeout`). ### Testing Plan - Although this does not change the interface itself, it changes its own session management logics, some existing tests are no longer valid. - I made changes to those tests, especially those of which validate session states(e.g. checking whether `initialize()` called). - Since now session is encapsulated with `SessionContext`, we cannot validate the initialized state of the session in `TestMcpSessionManager`, should validate it at `TestSessionContext`. - Added a simple test for reproducing the issue(`test_create_and_close_session_in_different_tasks`). - Also made a test for the new component: `SessionContext`. **Unit Tests:** - [x] I have added or updated unit tests for my change. - [x] All unit tests pass locally. ```plaintext =================================================================================== 3689 passed, 1 skipped, 2205 warnings in 63.39s (0:01:03) =================================================================================== ``` **Manual End-to-End (E2E) Tests:** _Please provide instructions on how to manually test your changes, including any necessary setup or configuration. Please provide logs or screenshots to help reviewers better understand the fix._ ### Checklist - [x] I have read the [CONTRIBUTING.md](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) document. - [x] I have performed a self-review of my own code. - [x] I have commented my code, particularly in hard-to-understand areas. - [x] I have added tests that prove my fix is effective or that my feature works. - [x] New and existing unit tests pass locally with my changes. - [x] I have manually tested my changes end-to-end. - [ ] ~~Any dependent changes have been merged and published in downstream modules.~~ `no deps has been changed` ### Additional context This PR is related to https://github.com/modelcontextprotocol/python-sdk/pull/1817 since it also fixes endless tool call awaiting. Co-authored-by: Kathy Wu <wukathy@google.com> COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/4025 from challenger71498:feat/task-based-mcp-session-manager f7f7cd0c9c96840361c30499d08c33a189f57d86 PiperOrigin-RevId: 856438147