安装python库xlwt的时候遇到超时的情况。

解决方法：修改超时时间：pip --default-timeout=1000 install -U pip
问题如下：Collecting xlwt
  Downloading xlwt-1.3.0-py2.py3-none-any.whl (99kB)

  Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.python.org', port=443): Read timed out. (read timeout=15)",)': /simple/xlwt/
Exception:
Traceback (most recent call last):
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 302, in _error_catcher
    yield
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 384, in read
    data = self._fp.read(amt)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\cachecontrol\filewrapper.py", line 60, in read
    data = self.__fp.read(amt)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\http\client.py", line 449, in read
    n = self.readinto(b)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\http\client.py", line 493, in readinto
    n = self.fp.readinto(b)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\socket.py", line 586, in readinto
    return self._sock.recv_into(b)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\ssl.py", line 1009, in recv_into
    return self.read(nbytes, buffer)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\ssl.py", line 871, in read
    return self._sslobj.read(len, buffer)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\ssl.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 "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\basecommand.py", line 215, in main
    status = self.run(options, args)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\commands\install.py", line 335, in run
    wb.build(autobuilding=True)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\wheel.py", line 749, in build
    self.requirement_set.prepare_files(self.finder)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\req\req_set.py", line 380, in prepare_files
    ignore_dependencies=self.ignore_dependencies))
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\req\req_set.py", line 620, in _prepare_file
    session=self.session, hashes=hashes)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 821, in unpack_url
    hashes=hashes
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 659, in unpack_http_url
    hashes)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 882, in _download_http_url
    _download_url(resp, link, content_file, hashes)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 603, in _download_url
    hashes.check_against_chunks(downloaded_chunks)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\utils\hashes.py", line 46, in check_against_chunks
    for chunk in chunks:
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 571, in written_chunks
    for chunk in chunks:
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\utils\ui.py", line 139, in iter
    for x in it:
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\download.py", line 560, in resp_read
    decode_content=False):
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 436, in stream
    data = self.read(amt=amt, decode_content=decode_content)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 401, in read
    raise IncompleteRead(self._fp_bytes_read, self.length_remaining)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python36\Lib\contextlib.py", line 99, in __exit__
    self.gen.throw(type, value, traceback)
  File "C:\Users\Administrator\venv\xwfproject1\lib\site-packages\pip\_vendor\urllib3\response.py", line 307, in _error_catcher
    raise ReadTimeoutError(self._pool, None, 'Read timed out.')
pip._vendor.urllib3.exceptions.ReadTimeoutError: HTTPSConnectionPool(host='pypi.python.org', port=443): Read timed out.