Function _stop_server_process

src/mcp/client/stdio.py:248–267

Closes stdin, waits out the grace period, then kills the whole tree. The escalation order is spec text; timeouts and tree-wide scope are SDK policy: https://modelcontextprotocol.io/specification/2025-11-25/basic/lifecycle#shutdown

(process: ServerProcess)

async def _stop_server_process(process: ServerProcess) -> None:
    """Closes stdin, waits out the grace period, then kills the whole tree.

    The escalation order is spec text; timeouts and tree-wide scope are SDK policy:
    https://modelcontextprotocol.io/specification/2025-11-25/basic/lifecycle#shutdown
    """
    assert process.stdin and process.stdout, "server process is spawned with pipes"

    await _close_pipe(process.stdin)
    if not await _wait_for_process_exit(process, PROCESS_TERMINATION_TIMEOUT):
        await _terminate_process_tree(process)
        # Until the event loop observes the death, the transport cannot close.
        if not await _wait_for_process_exit(process, _KILL_REAP_TIMEOUT):
            logger.warning("MCP server process %d is still alive after the kill escalation; abandoning it", process.pid)

    # Reaps surviving Windows job members now, not at GC; no-op on POSIX.
    close_process_job(process)
    # A kill survivor can hold the stdout pipe open; poison the reader anyway.
    await _close_pipe(process.stdout)
    _close_subprocess_transport(process)


async def _close_pipe(stream: AsyncResource) -> None: