when run demo.py and have a error

when I run pip install -r requirements.txt ,it has error
ERROR: Exception:
Traceback (most recent call last):
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/cli/base_command.py", line 153, in _main
status = self.run(options, args)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/commands/install.py", line 382, in run
resolver.resolve(requirement_set)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/legacy_resolve.py", line 201, in resolve
self._resolve_one(requirement_set, req)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/legacy_resolve.py", line 365, in _resolve_one
abstract_dist = self._get_abstract_dist_for(req_to_install)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/legacy_resolve.py", line 313, in _get_abstract_dist_for
req, self.session, self.finder, self.require_hashes
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/operations/prepare.py", line 194, in prepare_linked_requirement
progress_bar=self.progress_bar
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/download.py", line 465, in unpack_url
progress_bar=progress_bar
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/download.py", line 316, in unpack_http_url
progress_bar)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/download.py", line 551, in _download_http_url
_download_url(resp, link, content_file, hashes, progress_bar)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/download.py", line 253, in _download_url
hashes.check_against_chunks(downloaded_chunks)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/utils/hashes.py", line 80, in check_against_chunks
for chunk in chunks:
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/download.py", line 223, in written_chunks
for chunk in chunks:
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/utils/ui.py", line 160, in iter
for x in it:
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_internal/download.py", line 212, in resp_read
decode_content=False):
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_vendor/urllib3/response.py", line 564, in stream
data = self.read(amt=amt, decode_content=decode_content)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_vendor/urllib3/response.py", line 507, in read
data = self._fp.read(amt) if not fp_closed else b""
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_vendor/cachecontrol/filewrapper.py", line 65, in read
self._close()
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_vendor/cachecontrol/filewrapper.py", line 52, in _close
self.__callback(self.__buf.getvalue())
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_vendor/cachecontrol/controller.py", line 300, in cache_response
cache_url, self.serializer.dumps(request, response, body=body)
File "/home/python/anaconda3/envs/siammask/lib/python3.6/site-packages/pip/_vendor/cachecontrol/serialize.py", line 72, in dumps
return b",".join([b"cc=4", msgpack.dumps(data, use_bin_type=True)])
MemoryError