我正在使用urllib2从ftp和http服务器加载文件。
其中一些服务器仅支持每个IP一个连接。问题是,urllib2不会立即关闭连接。请看示例程序。
from urllib2 import urlopen
from time import sleep
url = 'ftp://user:pass@host/big_file.ext'
def load_file(url):
f = urlopen(url)
loaded = 0
while True:
data = f.read(1024)
if data == '':
break
loaded += len(data)
f.close()
#sleep(1)
print('loaded {0}'.format(loaded))
load_file(url)
load_file(url)
代码从一个只支持1个连接的ftp服务器加载两个文件(这里的两个文件是相同的)。这将打印以下日志:
loaded 463675266
Traceback (most recent call last):
File "conection_test.py", line 20, in <module>
load_file(url)
File "conection_test.py", line 7, in load_file
f = urlopen(url)
File "/usr/lib/python2.6/urllib2.py", line 126, in urlopen
return _opener.open(url, data, timeout)
File "/usr/lib/python2.6/urllib2.py", line 391, in open
response = self._open(req, data)
File "/usr/lib/python2.6/urllib2.py", line 409, in _open
'_open', req)
File "/usr/lib/python2.6/urllib2.py", line 369, in _call_chain
result = func(*args)
File "/usr/lib/python2.6/urllib2.py", line 1331, in ftp_open
fw = self.connect_ftp(user, passwd, host, port, dirs, req.timeout)
File "/usr/lib/python2.6/urllib2.py", line 1352, in connect_ftp
fw = ftpwrapper(user, passwd, host, port, dirs, timeout)
File "/usr/lib/python2.6/urllib.py", line 854, in __init__
self.init()
File "/usr/lib/python2.6/urllib.py", line 860, in init
self.ftp.connect(self.host, self.port, self.timeout)
File "/usr/lib/python2.6/ftplib.py", line 134, in connect
self.welcome = self.getresp()
File "/usr/lib/python2.6/ftplib.py", line 216, in getresp
raise error_temp, resp
urllib2.URLError: <urlopen error ftp error: 421 There are too many connections from your internet address.>
因为第一个连接没有关闭,所以第一个文件被加载了,而第二个文件加载失败。
但是当我在f.close()
后使用sleep(1)
时,错误就不会发生:
loaded 463675266
loaded 463675266
有没有办法强制关闭连接,以便第二次下载不会失败?
close()
时连接不会立即关闭...或者使用contextlib.closing
(调用close
)。 - Biggie