#4896 : Fix deadlock in MCPTool.message_handler when server sends tool/prompt…#4898
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manjunathshiva wants to merge 2 commits intomicrosoft:mainfrom
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#4896 : Fix deadlock in MCPTool.message_handler when server sends tool/prompt…#4898manjunathshiva wants to merge 2 commits intomicrosoft:mainfrom
manjunathshiva wants to merge 2 commits intomicrosoft:mainfrom
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… list_changed notifications message_handler was awaiting load_tools()/load_prompts() inline on notifications/tools/list_changed. load_tools() calls _ensure_connected() which sends a ping, but the session cannot process it while blocked waiting for an in-flight call_tool response — causing a deadlock. Replace inline reloads with debug logging. Tools/prompts will be refreshed on the next connect(reset=True) or explicit load_tools() call. Fixes microsoft#4896
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This is being worked on here: #4866 |
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Summary
message_handlerawaitsload_tools()/load_prompts()inline whennotifications/tools/list_changedarrives.
load_tools()calls_ensure_connected()→send_ping(), but the session can't process the ping whileblocked on an in-flight
call_toolresponse — deadlock.connect(reset=True)orexplicit
load_tools()call.tools/list_changedduring tool execution (e.g.mongodb-mcp-server) causesMCPStdioTool.call_toolto hang indefinitely.Fixes #4896
Test plan
MCPStdioToolwithmongodb-mcp-server—call_toolshould return without hangingconnect()connect(reset=True)still refreshes tools