@matthewd

Does this mean that if we have existing before_fork and on_worker_boot blocks in our pre-Rails 5.2.0 puma.rb file, we can now simply remove those blocks after upgrading to Rails 5.2.0?

The Puma repo still recommends the use of these blocks in its documentation:

If you're preloading your application and using ActiveRecord, it's recommended that you setup your connection pool [in on_worker_boot]

So there's just a little bit of conflicting information here. But I recognize that Rails 5.2.0 just came out so hopefully documentation will converge and this query will add a bit to that effort.

Does this mean that if we have existing before_fork and on_worker_boot blocks in our pre-Rails 5.2.0 puma.rb file, we can now simply remove those blocks after upgrading to Rails 5.2.0?

Yes. (Assuming they're doing AR connection management, of course.)

They're perfectly safe to leave there, so it's not called out in the upgrade guide, but they should no longer be necessary.