presto-main/src/main/java/io/prestosql/operator/PartitionedLookupSource.java/PartitionedLookupSource/getInMemorySizeInBytes
class PartitionedLookupSource:    @Override
    public long getInMemorySizeInBytes()
    {
        return Arrays.stream(lookupSources).mapToLong(LookupSource::getInMemorySizeInBytes).sum();
    }