is rocketmq transactional message 2PC or 3PC?

Question

I tend to believe 3PC ,but offical document says 2PC . offical document link: https://rocketmq.apache.org/docs/featureBehavior/04transactionmessage/ enter image description here

the reason why is think it is 3PC is the step to write msg to half msg queue. I think this step is eqaual to pre-commit in 3PC.

Answer 1

It's 2pc.

Because it's core step is:

1. send a half message to Broker.
2. when you commit the transaction than broker will transfer the half message to normal topic.