How many hearts can Redis use?

I use Redis on virtual machines and I can not decide how many hearts I should assign to them.

I know that Redis uses a single thread to respond to requests, but the documentation also states that some tasks are run in the background by different threads / processes.

I can assign more hearts than needed without wasting resources, but I do not like the idea of ​​exceeding the theoretical limit, which I suppose exists in this case.

Until now, I've had this:

Have I forgotten something? Are there any other tasks for which Redis can use additional hearts? Maybe replication or flows?