Cannot unpickle DocumentNode

Reporting issues with GraphQL-core 3

Unpickling of DocumentNode(s) fail since unpickling a FrozenList fails. I believe the root issue is that List is extended, and pickle assumes it may call append, resulting in a FrozenError.

[Cito]

This has now been solved in b9423b74ca9d22d009a1a4633b38b2bcd06c604b by using tuples instead of FrozenLists for lists of nodes, and by not pickling the Token links, as explained above. Will be available in v3.2.0rc4.

[Cito]

@corydolphin I like to move this forward, but I have limited time, so I would be glad if you or anybody else could help.

The first thing we need is a test that makes sure that document asts can be properly pickled and unpickled. So I added this at the bottom of test_schema_parser.py:

    def can_pickle_and_unpickle_kitchen_sink_schema(kitchen_sink_sdl):  # noqa: F811
        sys.setrecursionlimit(2000)
        doc = parse(kitchen_sink_sdl)
        dumped = pickle.dumps(doc)
        loaded = pickle.loads(dumped)
        assert loaded == doc

This test fails due to the FrozenError issue and passes if we replace the FrozenLists with an ordinary list.

However, it baffles me that I had to set sys.setrecursionlimit(2000) to make it pass, otherweise I get a RecursionError. The kitchen_sink document is actually not that complicated or deeply nested. Does anybody understand what’s going on here?