PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> It seems that since I switched from PostgreSQL 9.5 to 12, I started to have
> a memory leak.
Could you maybe collect a memory map from one of the bloated processes?
It'd go something like
* attach to process with gdb
* "call MemoryContextStats(TopMemoryContext)"
* quit gdb
* look in postmaster log for memory dump
You probably need to have debug symbols installed for step 2 to work.
regards, tom lane