presto-main/src/main/java/io/prestosql/execution/SqlTaskExecution.java/Status/decrementRemainingDriver
class Status:        public synchronized void decrementRemainingDriver(Lifespan lifespan)
        {
            checkState(per(lifespan).remainingDriver > 0, "Cannot decrement remainingDriver for Lifespan %s. Value is 0.", lifespan);
            per(lifespan).remainingDriver--;
            overallRemainingDriver--;
            checkLifespanCompletion(lifespan);
        }