Because transaction state is

1) stored in the page cache and so

2) can be moved freely between threads,

transactions can be served from a priority queue from a fixed number of workers.

Thus, #Glowdust has, by design, the ability to automatically balance CPU and memory use.

Memory pressure pushes back via I/O to persist overflowing tx state and serve page faults.

CPU pressure reduces time spent on each tx per worker, which makes tx state accumulate in memory, which releases CPU.