python-requests hanging when downloading a mass amount of files - python-2.7

Question

I am trying to use python-request package to download a mass amount of files(like 10k+) from the web, each file size from several k to the largest as 100mb.
my script can run through fine for maybe 3000 files but suddenly it will hang.
I ctrl-c it and see it stuck at
r = requests.get(url, headers=headers, stream=True)
File "/Library/Python/2.7/site-packages/requests/api.py", line 55, in get
return request('get', url, **kwargs)
File "/Library/Python/2.7/site-packages/requests/api.py", line 44, in request
return session.request(method=method, url=url, **kwargs)
File "/Library/Python/2.7/site-packages/requests/sessions.py", line 456, in request
resp = self.send(prep, **send_kwargs)
File "/Library/Python/2.7/site-packages/requests/sessions.py", line 559, in send
r = adapter.send(request, **kwargs)
File "/Library/Python/2.7/site-packages/requests/adapters.py", line 327, in send
timeout=timeout
File "/Library/Python/2.7/site-packages/requests/packages/urllib3/connectionpool.py", line 493, in urlopen
body=body, headers=headers)
File "/Library/Python/2.7/site-packages/requests/packages/urllib3/connectionpool.py", line 319, in _make_request
httplib_response = conn.getresponse(buffering=True)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py", line 1045, in getresponse
response.begin()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py", line 409, in begin
version, status, reason = self._read_status()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py", line 365, in _read_status
line = self.fp.readline(_MAXLINE + 1)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 476, in readline
data = self._sock.recv(self._rbufsize)
Here is my python code to do the download
basedir = os.path.dirname(filepath)
if not os.path.exists(basedir):
os.makedirs(basedir)
r = requests.get(url, headers=headers, stream=True)
with open(filepath, 'w') as f:
for chunk in r.iter_content(1024):
if chunk:
f.write(chunk)
f.flush()
I am not sure what went wrong, if anyone has a clue, please kindly share some insights.
Thanks.

Answer 1

This is not a duplicate of the question that #alfasin linked in their comment. Judging by the (limited) traceback you posted, the request itself is hanging (the first line shows it was executing r = requests.get(url, headers=headers, stream=True)).
What you should do is set a timeout and catch the exception that is raised when the request times out. Once you have the URL try it in a browser or with curl to ensure it responds properly, otherwise remove it from your list of URLs to request. If you find the misbehaving URL, please update your question with it.

Answer 2

I faced a similar situation and it seems like a bug in the requests package was causing this issue. Upgrading to requests package 2.10.0 fixed it for me.
For your reference the change log for Requests 2.10.0 shows that the embedded urllib3 was updated to version 1.15.1 Release history
And the release history for urllib3 (Release history ) shows that version 1.15.1 included fixes for:
Chunked transfer encoding when requesting with chunked=True. (Issue #790)
Fixed AppEngine handling of transfer-encoding header and bug in Timeout defaults checking. (Issue #763)