Repository navigation
stdio_client context manager hangs #360
Description
Describe the bug
When using the stdio_client context manager, the process is never cleaned up.
To Reproduce
Steps to reproduce the behavior:
import asyncio
from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client
async def run():
server_params = StdioServerParameters(
command="claude",
args=["mcp", "serve"],
)
async with stdio_client(server_params) as (read, write):
async with ClientSession(read, write) as _:
pass
print("exit ClientSession")
print("exit stdio_client")
if __name__ == "__main__":
asyncio.run(run())
Expected behavior
The program would print:
exit ClientSession
exit stdio_client
But it never exits the stdio_client context.
Activity
mroch commentedon Mar 25, 2025
stdio_serverseems to have a similar problem:this prints
insideand never exits.hwaxxer commentedon Mar 25, 2025
One could argue that's per design since
stdio_serveris built to run indefinitely. For thestdio_clienthowever, I think it makes sense to be able to start up the server, run a discrete task and then exit.dsp-ant commentedon Mar 25, 2025
Can you check with most recent master if it's fixed. I think #325 already addresses the issue
hwaxxer commentedon Mar 25, 2025
@dsp-ant Same problem still.
hwaxxer commentedon Mar 25, 2025
The proposed fix #361 still works fwiw, but I understand it's a bit of a workaround and not addressing the underlying issue.
mroch commentedon Mar 25, 2025
I disagree, but can move that discussion to a different issue. For example, the server might want to exit if it gets an uncaught exception (the current bug I'm facing), but even in normal circumstances, it could be checked into your repo and you switch commits, so it needs to restart a different version. For the LSP, vscode-languageclient respawns the server when it exits.
mroch commentedon Mar 29, 2025
#372 probably fixed this. it also adds a
process.terminate()like #361maxisbey commentedon Sep 29, 2025
As this issue hasn't had any activity since #372 I'm going to close it assuming it's been fixed. If it hasn't been fixed please feel free to re-open this issue!