2020 resolver runtime bug: get_topological_weights sanity checks fail

[luofanghao]

What did you want to do?

Due to some corporate packages included. So I cannot list the requirements here. sorry about that

Output

ERROR: Exception:                           
Traceback (most recent call last):       
  File "/opt/bb/lib/python3.8/site-packages/pip/_internal/cli/base_command.py", line 228, in _main
    status = self.run(options, args)     
  File "/opt/bb/lib/python3.8/site-packages/pip/_internal/cli/req_command.py", line 182, in wrapper
    return func(self, options, args)        
  File "/opt/bb/lib/python3.8/site-packages/pip/_internal/commands/install.py", line 378, in run
    to_install = resolver.get_installation_order(
  File "/opt/bb/lib/python3.8/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 191, in get_installation_order
    weights = get_topological_weights(graph)
  File "/opt/bb/lib/python3.8/site-packages/pip/_internal/resolution/resolvelib/resolver.py", line 242, in get_topological_weights
    assert len(weights) == len(graph)
AssertionError 

Additional information

I checked that:

len(weights) is 50 and len(graph) is 51

[pradyunsg]

Hi, thanks for filing this issue.

I don't think anything can be done here without information about what the graph looks like here. Please share the contents of the graph -- output of print(graph) would be necessary to even attempt to address this issue.

[luofanghao]

okay so I did print the graph and weights, here is what I found:
so the extra element in graph is the vertice "zope-interface", which is not shown in the weights.
and in the graph object:

>>> graph._forwards["zope-interface"]
{'<Python from Requires-Python>'}
>>> graph._backwards["zope-interface"]
set()

hope these are helpful. Let me know if you want to know more information!

[pradyunsg]

No, it's not. I can't figure out what's wrong without the entire graph.

Could you please sanitize the names of the packages and share the graph?

[no-response]

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.

[aaugustin]

I have a minimal reproduction that results in the same error in #9155.

[pradyunsg]

#9031 was where this was discussed at length and fixed.