Repeated host lookups failing in urllib2
- by reve_etrange
I have code which issues many HTTP GET requests using Python's urllib2, in several threads, writing the responses into files (one per thread).
During execution, it looks like many of the host lookups fail (causing a name or service unknown error, see appended error log for an example).
Is this due to a flaky DNS service? Is it bad practice to rely on DNS caching, if the host name isn't changing? I.e. should a single lookup's result be passed into the urlopen?
Exception in thread Thread-16:
Traceback (most recent call last):
File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
self.run()
File "/home/da/local/bin/ThreadedDownloader.py", line 61, in run
page = urllib2.urlopen(url) # get the page
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 1170, in http_open
return self.do_open(httplib.HTTPConnection, req)
File "/usr/lib/python2.6/urllib2.py", line 1145, in do_open
raise URLError(err)
URLError: <urlopen error [Errno -2] Name or service not known>
