code: func makeDatabaseHandles() int {
  	limit, err := fdlimit.Maximum()
  	if err != nil {
  		Fatalf("Failed to retrieve file descriptor allowance: %v", err)
  	}
  	raised, err := fdlimit.Raise(uint64(limit))
  	if err != nil {
  		Fatalf("Failed to raise file descriptor allowance: %v", err)
  	}
  	return int(raised / 2) // Leave half for networking and other stuff
  }
docs: // makeDatabaseHandles raises out the number of allowed file handles per process
  // for Geth and returns half of the allowance to assign to the database.