presto-main/src/main/java/io/prestosql/operator/DriverFactory.java/DriverFactory/noMoreDrivers
class DriverFactory:    public synchronized void noMoreDrivers()
    {
        if (closed) {
            return;
        }
        if (encounteredLifespans.size() != closedLifespans.size()) {
            Sets.difference(encounteredLifespans, closedLifespans).forEach(this::noMoreDrivers);
            verify(encounteredLifespans.size() == closedLifespans.size());
        }
        closed = true;
        for (OperatorFactory operatorFactory : operatorFactories) {
            operatorFactory.noMoreOperators();
        }
    }