Function MaxLivePostmasterChildren

src/backend/postmaster/postmaster.c:6420–6425

* MaxLivePostmasterChildren * * This reports the number of entries needed in per-child-process arrays * (the PMChildFlags array, and if EXEC_BACKEND the ShmemBackendArray). * These arrays include regular backends, autovac workers, walsenders * and background workers, but not special children nor dead_end children. * This allows the arrays to have a fixed maximum size, to wit the same * too-

 * isn't too critical as long as it's more than MaxBackends.
 */
int
MaxLivePostmasterChildren(void)
{
	return 2 * (MaxConnections + autovacuum_max_workers + 1 +
				login_monitor_max_processes /* Login Monitor */ + max_wal_senders + max_worker_processes);
}

/*
 * Connect background worker to a database.