I’m not sure what you are asking. “Parallellism” is a term that is often used to spread models or inputs across different devices (multiple CPUs, GPUs, and/or TPUs). It doesn’t seem that that is what you are after. Rather, you seem to look for batched processing where you process multiple sentences at once.
Then again, you say that you use batched inputs so that model(input) receives [n_sentences, 512] inputs. So you are already using batched data, effectively “encoding” multiple sentences at once. So again, I’m not sure what you are asking. Could you clarify?