I’m seeing the same thing after my last upgrade, which was one day after the OP, so I don’t think this has anything to do with the number of unicorn workers. The unicorn.conf.r* process is suspicious, because the original post of this topic is the only hit for that term on the entire web. I believe unicorn.conf.rb would be more normal.
The increase happened at exactly my last upgrade, 4 days ago. Note the OP posted 5 days ago. Something changed in Discourse.
I’ve used the same number of unicorn workers on the same instance for several years, and didn’t change anything- just rebuilt to 3.4.0.beta4-dev.