問題描述

我正在嘗試使用帶有超時選項的 ftplib.FTP() 作為特定主機名的超時值.但我正在經(jīng)歷奇怪的行為.為了測試它，我編寫了一段非常簡單的代碼.

I am trying to use ftplib.FTP() with timeout option as some timeout value for a particular hostname. But i am experiencing weird behaviour. To test it i have written a very simple piece of code.

import ftplib
from ftplib import FTP
ftp = ftplib.FTP("google.com",timeout=2)

API文檔說以秒為單位輸入超時值，但似乎需要更長的時間，對我來說幾乎需要8秒以上.誰能解釋一下這個行為.我正在使用 python2.7

The API document says to enter timeout value in seconds, but it seems that it takes longer than that, for me it almost takes more than 8 secs. Can anybody please explain the behaviour.I am using python2.7

推薦答案

ftplib.FTP 調(diào)用 socket.create_connection().根據(jù)到文檔 https://docs.python.org/2/library/socket.html#socket.create_connection

ftplib.FTP invokes socket.create_connection(). According to the docs https://docs.python.org/2/library/socket.html#socket.create_connection

如果主機是非數(shù)字主機名，它將嘗試為兩者解析AF_INET 和 AF_INET6，然后嘗試連接所有可能的依次分配地址，直到連接成功.

if host is a non-numeric hostname, it will try to resolve it for both AF_INET and AF_INET6, and then try to connect to all possible addresses in turn until a connection succeeds.

快速檢查 google.com 將顯示大約一打(或更多)取決于您所在國家/地區(qū)的地區(qū).你的 2 秒超時應(yīng)用于每個主機.

A quick check of google.com will show about a dozen (or more) depending on your region of the country. Your 2 second timeout is applied to each of the hosts.

如果您想將總時間限制為 2 秒，請先進行查找并將數(shù)字地址傳遞給您的 ftplib.FTP 調(diào)用:

If you want to limit total time to 2 seconds, do the lookup first and pass the numeric address to your ftplib.FTP call:

import socket, ftplib
host = socket.gethostbyname('google.com')
ftp = ftplib.FTP(host, timeout=2)

這篇關(guān)于ftplib.FTP 超時行為不一致的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！