[pcmoritz]

Author here. For CapnProto see the answer to the other comment above.

Concerning dill, we have been using it for serializing function and classes (and then switched to cloudpickle because it supports some Python functionality better and the community around it is very active responsive); cloudpickle/dill are great in that they support a very wide variety of Python objects, especially concerning code (functions, lambdas, classes); it is less ideal for large data, because there is no zero copy mechanism, the format is not standardized and serialization/deserialization can be slow, sometimes it is slower than pickle. We do fall back to cloudpickle for objects we don't support like Python lambdas. We also use it to serialize class definitions, so the data associated to classes is serialized using the solution presented above and the code/methods are serialized using cloudpickle. This combines the advantages of both solutions.