presto-main/src/main/java/io/prestosql/operator/PartitionedLookupSourceFactory.java/SpillAwareLookupSourceProvider/close
class SpillAwareLookupSourceProvider:        @Override
        public void close()
        {
            LookupSource lookupSource;
            lock.readLock().lock();
            try {
                lookupSource = suppliedLookupSources.remove(this);
            }
            finally {
                lock.readLock().unlock();
            }
            if (lookupSource != null) {
                lookupSource.close();
            }
        }