Have one writer actor per engine that manages all index writers.

[ChillFish8]

As it stands right now, you can create n indexes which each create at a bare minimum 2-3 threads, this isn't great for efficiency both at idle and indexing.

If you create an index with a 12 thread writer and then another of the same number of threads then add documents to them, the system will essentially fight itself over the CPU time, this is not massively ideal slowing both indexing operations down vs queuing the operations one after another.

This not only improves the per index indexing performance but also makes indexes much cheaper to make dropping to only 1 thread in a best-case scenario, the #37 issue would basically make this 0 potentially allowing the creation of 'micro' indexes.