I suspect you don't know what you're talking about.
Using processes instead of threads doesn't necessarily make you 'heavy on
resources'. It doesn't necessarily indicate that you are 'stuck' in any
way at all. It requires greater discipline than using threads, and the
context switch time is slightly higher, making it an inappropriate
technique for insane loads, but in every other way using processes is
Think: what happens if a single MySQL server thread crashes. Who knows
what state it corrupted first: best take the whole server down.
If a PostgreSQL server crashes, the others are unaffected, their address
spaces inviolate save for a strictly-defined shared memory region: they
can generally carry on.