We've got some OOM fuzz test cases getting reported, but these aren't
very interesting. The OOMs, after some investigation, are confirmed to
be happening because the test is simply allocating thousands of
instances with massive tables, quickly exceeding the 2GB memory
threshold for fuzzing. This isn't really interesting because this is
expected behavior if you instantiate these sorts of modules.
This commit updates the fuzz test case generator to have a "prediction"
for each module how much memory it will take to instantiate it. This
prediction is then used to avoid instantiating new modules if we predict
that it will exceed our memory limit. The limits here are intentionally
very squishy and imprecise. The goal here is to still generate lots of
interesting test cases, but not ones that simply exhaust memory
trivially.
0a020918b5