Python Socket Connect 设置超时无效

Question

准备检测一个本地端口是否开放，设置了0.01秒超时，但是实际运行了10多秒才抛出异常。如何解决？

import socket
socket.setdefaulttimeout(0.01)
socket.getaddrinfo("123123231", 12345)

Answer 1

setdefaulttimeout 是配置socket实例的

import socket
socket.setdefaulttimeout(0.01)
s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
# 也可以在这设置
# s.settimeout(0.01)
s.connect(("123123231", 12345))

Answer 2

import socket
socket.setdefaulttimeout(0.01) 
socket.getaddrinfo("123123231", 12345)

这个setdefaulttimeout对socket模块方法没有用处，只是针对socket.socket对象设置超时。这点从源代码中可以看出。

def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT,
                      source_address=None):
    host, port = address
    err = None
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
        af, socktype, proto, canonname, sa = res
        sock = None
        try:
            sock = socket(af, socktype, proto)
            if timeout is not _GLOBAL_DEFAULT_TIMEOUT:
                sock.settimeout(timeout)
            if source_address:
                sock.bind(source_address)
            sock.connect(sa)
            return sock

        except error as _:
            err = _
            if sock is not None:
                sock.close()

    if err is not None:
        raise err
    else:
        raise error("getaddrinfo returns an empty list")
        
def getaddrinfo(host, port, family=0, type=0, proto=0, flags=0):
    addrlist = []
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
        af, socktype, proto, canonname, sa = res
        addrlist.append((_intenum_converter(af, AddressFamily),
                         _intenum_converter(socktype, SocketKind),
                         proto, canonname, sa))
    return addrlist

解决方案：(python3代码)

import socket
socket.setdefaulttimeout(0.01)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
    sock.connect(("123123231", 12345))
except socket.timeout as e:
    print("timeout")
    pass