René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Stateless Mode memory leak","articleBody":"**Describe the bug**\nStateless mode with Streamable-HTTP leaks memory. The `StreamableHTTPSessionManager` stateless server task group never exits and the `_task` list grows with each request leading to always increasing memory usage. \n\n**Expected behavior**\nStateless server exits after handling the request freeing up the resources\n\n**Steps to reproduce**\n1. Create minimal MCP server:\n```python\nfrom mcp.server.fastmcp import FastMCP\n\nmcp = FastMCP(\"StatelessServer\", stateless_http=True)\n\n\n@mcp.tool()\ndef task_size() -\u003e int:\n    return len(mcp.session_manager._task_group._tasks)\n\n\nif __name__ == \"__main__\":\n    mcp.run(transport=\"streamable-http\")\n\n```\n2. Create minimal MCP client:\n```python\nimport asyncio\n\nfrom fastmcp import Client\nfrom fastmcp.client.transports import StreamableHttpTransport\nfrom mcp.types import CallToolResult\n\nasync def execute_mcp_tool_call():\n    transport = StreamableHttpTransport(\"http://localhost:8000/mcp/\")\n\n    async with Client(transport) as client:\n        tools = await client.list_tools()\n        print(tools)\n\n        result = await client.call_tool(\"task_size\")\n        print(result)\n\n\nasyncio.run(execute_mcp_tool_call())\n```\n3. Do multiple requests\n4. Tool will return the size of pending tasks in session manager task group and it is always increasing:\n```\n[TextContent(type='text', text='23', annotations=None)]\n[TextContent(type='text', text='27', annotations=None)]\n[TextContent(type='text', text='31', annotations=None)]\n```","author":{"url":"https://github.com/algirdasci","@type":"Person","name":"algirdasci"},"datePublished":"2025-05-19T17:00:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":16},"url":"https://github.com/756/python-sdk/issues/756"}