Change default for registrationRequired?

[Martin Grotzke]

Hi all, 

here are some questions where are looking for your feedback:

* what is the setting for setRegistrationRequired that you're using? (the default currently is false) 

* would you be comfortable with the default for registrationRequired being changed to true?

* what are other settings that you'd like to see set differently by default?

Cheers, 

Martin

PS the issue for the registrationRequired=true default is https://github.com/EsotericSoftware/kryo/issues/398

[Ian O'Connell]

For Chill/Scalding

* default registration required i false. Anything else would be very painful for something like scalding (and Spark too), functions are typed in a way that doesn't leak full tree's. Users are mostly un aware of the existence of Kryo. Users incur a performance hit via lack of registration, but the convenience far out weighs that.

* Changing the default I would be -1 on. We can stick the false default in a few places, but given this winds up being runtime failures for people around a setting it feels unnecessary to me. Better than corruption, but users can set it if they are concerned about security in any default builder for their Kryo. 

* Nothing springs to mind currently

[Nate]

I think it makes sense to make registration required by default for security and performance reasons, as described in the blog post. Chill/Scalding and other projects can configure Kryo differently and is their responsibility for understanding the ramifications.

-Nate