After receiving the new transactions, we will cache the transaction in the transaction pool and wait for the miner to package it.

If the parent of the transaction exists in the transaction pool, then the transaction is placed directly into the transaction pool. Otherwise put it in an orphan pool and finally process these transactions。

Orphan transaction : Due to network delay, the received transaction may be a transaction that references a transaction that has not been added to the transaction pool for the time being.

Here is a activity diagram of this Transaction pool processing: