One thread pool per thread and consequently at least one thread per field leads to many threads when faceting on many fields, even if those are very small fields. Having a single thread pool per core, that is shared by the fields, lowers this overhead.
One thread pool per thread and consequently at least one thread per field leads to many threads when faceting on many fields, even if those are very small fields. Having a single thread pool per core, that is shared by the fields, lowers this overhead.