Sorry if I offend anybody, but this sounds like such a bad idea. I have been running various versions of postgres in production for 15 years with thousands of processes on super beefy machines, and I can tell you without a doubt that sometimes those processes crash - specially if you are running any of the extensions. Nevertheless, Postgres has 99% of the time proven to be resilient. The idea that a bad client can bring the whole cluster down because it hit a bug sounds scary. Every try creating a spatial index on thousands/millions of records that have nasty overly complex or badly digitized geometries? Sadly, crashes are part of that workflow, and changing this from process to threading would mean all the other clients also crashing and cutting connections. This as a potential problem because I want to avoid context switching overhead or cache misses, no thanks.