In a real-time database system, a new commit protocol called Double Space Commit (2SC) has been developed to ensure transaction atomicity. This protocol allows transactions to access data optimistically, reducing data inaccessibility and priority inversion. When a transaction aborts, only certain dependent transactions abort while others continue normally. Simulation experiments show that 2SC outperforms other protocols like PROMPT and DDCR, seamlessly integrating with existing concurrency control protocols for transaction serialization and atomic commitment.