void runUntilDone(final ScheduledExecutorService executor) {
            self = executor.scheduleAtFixedRate(this, 1000, 1000, TimeUnit.MILLISECONDS);
        }
Self-cancelling tasks that periodically checks for the pending queue to clear before shutting down the
{@code Connection}. Once it does that, it self cancels the scheduled job in the executor.
gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/Connection.java