[BUG] Tavily MCP server hitting Out of memory

[jirispilka]

The Tavily MCP server keeps restarting the proxy repeatedly, which ultimately leads to an Out of Memory error

Run

2025-10-29T06:59:47.122Z Tavily MCP server running on stdio
2025-10-29T06:59:47.130Z INFO  MCP Proxy Client started successfully
2025-10-29T06:59:47.131Z INFO  Session initialized {"sessionId":"1e83b370-fdf4-4f45-bc70-23513a476f0a"}
2025-10-29T06:59:47.133Z INFO  Not charging for method: initialize
2025-10-29T06:59:47.689Z INFO  Received MCP request {"sessionId":"1e83b370-fdf4-4f45-bc70-23513a476f0a","body":{"method":"notifications/initialized","jsonrpc":"2.0"}}
2025-10-29T06:59:47.691Z INFO  Not charging for method: notifications/initialized
2025-10-29T06:59:47.819Z INFO  Establishing new SSE stream {"sessionId":"1e83b370-fdf4-4f45-bc70-23513a476f0a"}
2025-10-29T06:59:48.247Z INFO  Received MCP request {"sessionId":"1e83b370-fdf4-4f45-bc70-23513a476f0a","body":{"method":"tools/list","params":{},"jsonrpc":"2.0","id":1}}
2025-10-29T06:59:48.265Z INFO  Not charging for method: tools/list
2025-10-29T06:59:48.281Z INFO  Received MCP request {"method":"tools/list","request":{"method":"tools/list","params":{}}}
2025-10-29T06:59:53.218Z INFO  Received MCP request {"sessionId":"1e83b370-fdf4-4f45-bc70-23513a476f0a","body":{"method":"tools/call","params":{"name":"tavily-extract","arguments":{"urls":"[array]","extract_depth":"advanced","include_images":false,"format":"text","include_favicon":false}},"jsonrpc":"2.0","id":2}}
2025-10-29T06:59:53.220Z INFO  Received MCP request {"method":"tools/call","request":{"method":"tools/call","params":{"name":"tavily-extract","arguments":{"urls":"[array]","extract_depth":"advanced","include_images":false,"format":"text","include_favicon":false}}}}
2025-10-29T06:59:53.249Z INFO  Charged for tavily-extract request: tools/call
2025-10-29T07:00:48.863Z INFO  Received MCP request {"sessionId":null,"body":{"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{"tools":"[object]"},"clientInfo":{"name":"@n8n/n8n-nodes-langchain.mcpClientTool","version":"1.2"}},"jsonrpc":"2.0","id":0}}
2025-10-29T07:00:48.864Z INFO  Starting MCP Proxy Client {"command":["npx","tavily-mcp"]}
2025-10-29T07:00:58.930Z Tavily MCP server running on stdio
2025-10-29T07:00:58.937Z INFO  MCP Proxy Client started successfully
2025-10-29T07:00:59.025Z INFO  Session initialized {"sessionId":"af0ea093-5e1c-4aa8-b235-865e51d96a12"}
2025-10-29T07:00:59.041Z INFO  Not charging for method: initialize
2025-10-29T07:01:00.073Z INFO  Received MCP request {"sessionId":"af0ea093-5e1c-4aa8-b235-865e51d96a12","body":{"method":"notifications/initialized","jsonrpc":"2.0"}}
2025-10-29T07:01:00.074Z INFO  Not charging for method: notifications/initialized
2025-10-29T07:01:00.213Z INFO  Establishing new SSE stream {"sessionId":"af0ea093-5e1c-4aa8-b235-865e51d96a12"}
2025-10-29T07:01:00.652Z INFO  Received MCP request {"sessionId":"af0ea093-5e1c-4aa8-b235-865e51d96a12","body":{"method":"tools/list","params":{},"jsonrpc":"2.0","id":1}}
2025-10-29T07:01:00.654Z INFO  Not charging for method: tools/list
2025-10-29T07:01:00.681Z INFO  Received MCP request {"method":"tools/list","request":{"method":"tools/list","params":{}}}
2025-10-29T07:01:05.496Z INFO  Received MCP request {"sessionId":"af0ea093-5e1c-4aa8-b235-865e51d96a12","body":{"method":"tools/call","params":{"name":"tavily-extract","arguments":{"urls":"[array]","extract_depth":"advanced","include_images":false,"format":"text","include_favicon":false}},"jsonrpc":"2.0","id":2}}
2025-10-29T07:01:05.505Z INFO  Received MCP request {"method":"tools/call","request":{"method":"tools/call","params":{"name":"tavily-extract","arguments":{"urls":"[array]","extract_depth":"advanced","include_images":false,"format":"text","include_favicon":false}}}}
2025-10-29T07:01:05.626Z INFO  Charged for tavily-extract request: tools/call
2025-10-29T07:01:52.577Z INFO  Received MCP request {"sessionId":null,"body":{"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{"tools":"[object]"},"clientInfo":{"name":"@n8n/n8n-nodes-langchain.mcpClientTool","version":"1.2"}},"jsonrpc":"2.0","id":0}}
2025-10-29T07:01:52.579Z INFO  Starting MCP Proxy Client {"command":["npx","tavily-mcp"]}

[jirispilka]

It might be a problem in ts template as well, fyi @MQ37 @JJetmar

[JJetmar]

@jirispilka Hmm, I am having hard time to reproduce this behavior. 🤔
Do we know any specific steps?

[MQ37]

This happens when you connect multiple clients, it basically spawns the tavily-mcp stdio server instance for each connected client. For this specific MCP server we can change behavior to spawn only one tavily-mcp stdio instance and route all clients there - but this is not a solution for stateful mcp servers.

See this run: https://console.apify.com/view/runs/SlZC2ZeaiebpUeaGr

[jirispilka]

Oh, I see, so the client is not closing the connection and creating a new session (in the run from the user it is: @n8n/n8n-nodes-langchain.mcpClientTool).

I can see two solutions:

1. Clean up idle sessions (as we do in Python) - this might not help if the client creates many connections fast
2. Use stateless mode, i.e., create one instance of the process (as we do in Python). This server is stateless anyway, IMO

I would go for the second one.

[jirispilka]

We've discussed this with @JJetmar so let me expand on it, because I was not able to clearly explain

If we go with stateless mode and single process:

• messages from different clients can be mixed or corrupted over a shared stdin/stdout stream
• blocking I/O - one long or stuck request blocks the whole process, delaying others
• no isolation - all sessions share the same memory; a crash or leak in one breaks all
• not scaleable – a single process and stream become a bottleneck

Bottom line: it should be one client using the server. To be safe we should start for each session a new process. But then we'll run out of the memory soon.

Should we start a new standby Actor of every new session?
I don't think it is possible, just putting it here as another option.