presto-main/src/main/java/io/prestosql/execution/scheduler/group/FixedLifespanScheduler.java/FixedLifespanScheduler/onLifespanFinished
class FixedLifespanScheduler:    @Override
    public void onLifespanFinished(Iterable<Lifespan> newlyCompletedDriverGroups)
    {
        checkState(initialScheduled);

        SettableFuture<?> newDriverGroupReady;
        synchronized (this) {
            for (Lifespan newlyCompletedDriverGroup : newlyCompletedDriverGroups) {
                checkArgument(!newlyCompletedDriverGroup.isTaskWide());
                recentlyCompletedDriverGroups.add(newlyCompletedDriverGroup);
            }
            newDriverGroupReady = this.newDriverGroupReady;
        }
        newDriverGroupReady.set(null);
    }