[Bug]: Socket resource leak in _check_port_available when port is in use

[ze-mu-zhou]

Bug Description

AGFSManager._check_port_available() (openviking/agfs_manager.py lines 113–123) creates a socket but only closes it on the success path. When sock.bind() raises OSError (port already in use), the code raises RuntimeError without ever closing the socket, leaking a file descriptor.

def _check_port_available(self) -> None:
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    try:
        sock.bind(("localhost", self.port))
        sock.close()          # Only reached on success
    except OSError as e:
        raise RuntimeError(   # sock is never closed here
            f"AGFS port {self.port} is already in use..."
        ) from e

Steps to Reproduce

import socket
from openviking.agfs_manager import AGFSManager

# Occupy a port
blocker = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
blocker.bind(("localhost", 19998))
blocker.listen(1)

# Call _check_port_available on the occupied port
mgr = AGFSManager.__new__(AGFSManager)
mgr.port = 19998

try:
    mgr._check_port_available()
except RuntimeError:
    pass  # Socket fd leaked here

blocker.close()

Expected Behavior

The socket should be closed on both success and failure paths, e.g. using finally: sock.close().

Actual Behavior

Python emits a ResourceWarning confirming the socket was never closed:

Exception ignored in: <socket.socket fd=664, family=2, type=1, proto=0>
ResourceWarning: unclosed <socket.socket fd=664, family=2, type=1, proto=0>

Each failed call leaks one file descriptor.

Minimal Reproducible Example

import socket
import warnings

warnings.simplefilter("error", ResourceWarning)

from openviking.agfs_manager import AGFSManager

blocker = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
blocker.bind(("localhost", 19998))
blocker.listen(1)

mgr = AGFSManager.__new__(AGFSManager)
mgr.port = 19998

try:
    mgr._check_port_available()
except RuntimeError:
    pass

import gc
gc.collect()
# ResourceWarning: unclosed <socket.socket fd=664, ...>

blocker.close()

Error Logs

Exception ignored in: <socket.socket fd=664, family=2, type=1, proto=0>
ResourceWarning: unclosed <socket.socket fd=664, family=2, type=1, proto=0>

OpenViking Version

0.1.10 (main branch, 2026-02-07)

Python Version

3.13.7

Operating System

Windows

Model Backend

Other

Additional Context

Fix is straightforward — move sock.close() into a finally block:

def _check_port_available(self) -> None:
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    try:
        sock.bind(("localhost", self.port))
    except OSError as e:
        raise RuntimeError(
            f"AGFS port {self.port} is already in use..."
        ) from e
    finally:
        sock.close()

In retry scenarios or test suites where _check_port_available is called repeatedly with an occupied port, this leak can accumulate and eventually exhaust file descriptors.