It is difficult for a distributed real-time transaction to satisfy its deadline because of the complexities of its commitment processing. A new commit protocol called A2SC (active double space commit) is proposed, which cater for the distributed real-time transaction commitment processing. All kinds of dependencies caused from data conflicts access are analyzed. When data conflicts between the prepared transaction and the execution transactions occur, A2SC allows the execution transactions to access the locked data optimistically in a controlled manner. When the prepared transaction aborts, only transactions in its abort dependency set are aborted. Furthermore, a notion of fruitless run is proposed. When a transaction finds fruitless run, it will actively abort. Extensive simulation experiments have been performed to compare the performance of the A2SC with other protocols such as the base protocol, the PROMPT and the DDCR. The simulation results show that A2SC is highly successful in minimizing the number of missed transactions deadlines. So A2SC caters for high-performance distributed real-time transaction.%由于提交处理的复杂性,分布式实时事务很难满足其截止期.提出了一种新的提交协议A2SC(主动的双空间提交),它适合于分布式实时事务提交处理的需要.分析了由于数据冲突访问而形成的各种依赖关系.当处于准备状态的事务和处于提交状态的事务发生数据冲突访问时,A2SC允许处于执行状态的事务在一种控制的方式下乐观地访问锁住的数据.当处于准备状态的事务夭折时,仅仅只有其夭折依赖集中的事务夭折.进一步提出了"没有结果的运行"的观念.当一个事务发现它是没有结果的允许时,它将主动夭折.进行了广泛的模拟实验比较A2SC和其它协议比如基准协议、PROMPT和DDCR的性能.模拟结果表明A2SC在最小化错过截止期的事务数方面较成功,因此A2SC适合于高性能分布式实时事务.
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