nitro.go
func MemoryInUse() (sz int64) {
	buf := dbInstances.MakeBuf()
	defer dbInstances.FreeBuf(buf)
	iter := dbInstances.NewIterator(CompareNitro, buf)
	for iter.SeekFirst(); iter.Valid(); iter.Next() {
		db := (*Nitro)(iter.Get())
		sz += db.MemoryInUse()
	}

	return
}
func MemoryInUse() (sz int64) {
	buf := dbInstances.MakeBuf()
	defer dbInstances.FreeBuf(buf)
	iter := dbInstances.NewIterator(CompareNitro, buf)
	for iter.SeekFirst(); iter.Valid(); iter.Next() {
		db := (*Nitro)(iter.Get())
		sz += db.MemoryInUse()
	}

	return
}
// MemoryInUse returns total memory used by all Nitro instances in the current process