解决pip下载超时

pip._vendor.requests.packages.urllib3.exceptions.ReadTimeoutError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Read timed out.

Collecting tensorflow==1.2.1
Downloading https://files.pythonhosted.org/packages/e1/18/23a447f822daba3101d84f981d10f5eacd0ccd9a541bd4d2525eec0cba81/tensorflow-1.2.1-cp36-cp36m-win_amd64.whl (21.2MB)

Exception:
Traceback (most recent call last):
File "E:python_workplacevenvlibsite-packagespip\_vendor equestspackagesurllib3 esponse.py", line 232, in _error_catcher
yield
File "E:python_workplacevenvlibsite-packagespip\_vendor equestspackagesurllib3 esponse.py", line 314, in read
data = self._fp.read(amt)
File "E:python_workplacevenvlibsite-packagespip\_vendorcachecontrolfilewrapper.py", line 60, in read
data = self.__fp.read(amt)
File "F:Pythonlibhttpclient.py", line 449, in read
n = self.readinto(b)
File "F:Pythonlibhttpclient.py", line 493, in readinto
n = self.fp.readinto(b)
File "F:Pythonlibsocket.py", line 586, in readinto
return self._sock.recv_into(b)
File "F:Pythonlibssl.py", line 1009, in recv_into
return self.read(nbytes, buffer)
File "F:Pythonlibssl.py", line 871, in read
return self._sslobj.read(len, buffer)
File "F:Pythonlibssl.py", line 631, in read
v = self._sslobj.read(len, buffer)
socket.timeout: The read operation timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "E:python_workplacevenvlibsite-packagespipasecommand.py", line 215, in main
status = self.run(options, args)
File "E:python_workplacevenvlibsite-packagespipcommandsinstall.py", line 324, in run
requirement_set.prepare_files(finder)
File "E:python_workplacevenvlibsite-packagespip eq eq_set.py", line 380, in prepare_files
ignore_dependencies=self.ignore_dependencies))
File "E:python_workplacevenvlibsite-packagespip eq eq_set.py", line 620, in _prepare_file
session=self.session, hashes=hashes)
File "E:python_workplacevenvlibsite-packagespipdownload.py", line 821, in unpack_url
hashes=hashes
File "E:python_workplacevenvlibsite-packagespipdownload.py", line 659, in unpack_http_url
hashes)
File "E:python_workplacevenvlibsite-packagespipdownload.py", line 882, in _download_http_url
_download_url(resp, link, content_file, hashes)
File "E:python_workplacevenvlibsite-packagespipdownload.py", line 603, in _download_url
hashes.check_against_chunks(downloaded_chunks)
File "E:python_workplacevenvlibsite-packagespiputilshashes.py", line 46, in check_against_chunks
for chunk in chunks:
File "E:python_workplacevenvlibsite-packagespipdownload.py", line 571, in written_chunks
for chunk in chunks:
File "E:python_workplacevenvlibsite-packagespiputilsui.py", line 139, in iter
for x in it:
File "E:python_workplacevenvlibsite-packagespipdownload.py", line 560, in resp_read
decode_content=False):
File "E:python_workplacevenvlibsite-packagespip\_vendor equestspackagesurllib3 esponse.py", line 357, in stream
data = self.read(amt=amt, decode_content=decode_content)
File "E:python_workplacevenvlibsite-packagespip\_vendor equestspackagesurllib3 esponse.py", line 324, in read
flush_decoder = True
File "F:Pythonlibcontextlib.py", line 99, in __exit__
self.gen.throw(type, value, traceback)
File "E:python_workplacevenvlibsite-packagespip\_vendor equestspackagesurllib3 esponse.py", line 237, in _error_catcher
raise ReadTimeoutError(self._pool, None, 'Read timed out.')
pip._vendor.requests.packages.urllib3.exceptions.ReadTimeoutError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Read timed out.

使用命令：

pip --default-timeout=100