presto-orc/src/main/java/io/prestosql/orc/OrcOutputBuffer.java/OrcOutputBuffer/getRetainedSize
class OrcOutputBuffer:    @Override
    public long getRetainedSize()
    {
        return INSTANCE_SIZE + compressedOutputStream.getRetainedSize() + slice.getRetainedSize() + SizeOf.sizeOf(compressionBuffer);
    }