presto-main/src/main/java/io/prestosql/SystemSessionProperties.java/SystemSessionProperties/getConcurrentLifespansPerNode
class SystemSessionProperties:    public static OptionalInt getConcurrentLifespansPerNode(Session session)
    {
        Integer result = session.getSystemProperty(CONCURRENT_LIFESPANS_PER_NODE, Integer.class);
        if (result == 0) {
            return OptionalInt.empty();
        }
        checkArgument(result > 0, "Concurrent lifespans per node is negative: %s", result);
        return OptionalInt.of(result);
    }