Long-lived Transaction Research Articles

Optimizing a Long-Lived Transaction with Verification Function

We have considered a method called Enhanced Rollback Migration Protocol, which potentially has the effects of compressing the period of compensations in a long-lived transaction, since before. In general, a compensation transaction can recover an irregular status of a long-lived transaction into the original status without holding unnecessary resources by making its consistency tentatively loose. However, it has also been pointed out that there is a difficulty of maintaining the isolation between a pair of transactions when executed in parallel. In particular, this could be more prominent under modernized scalable cloud environments. Thus, there is a proposal for concurrency control for the service level. However, there is still another risk that more computer resources will be consumed than actually necessary and an unnecessary stagnation of the processing will be caused if concurrency control is naively applied without careful consideration. Therefore, we need to implement a functionality which can optimize the processing of a long-lived transaction by selecting a suitable method between concurrency control and compensation transactions. In this paper, we propose a method in which optimistic concurrency control is applied for long-lived transactions. Furthermore, a pair of verification phases is carried out. At the beginning from a safe point, an attempt of verification is done. Then if the difficulty of isolation on a long-lived transaction executed under a competitive situation is estimated, concurrency control for the service level is applied. Alternatively, a long-lived transaction without any concurrency control is executed. At the next reachable safe point, another attempt of verification is performed. Then if a failure of serialization is detected, a set of compensation transactions is invoked to recover the original long-lived transaction by returning to the first safe point. We evaluated this approach by using numerical simulations and confirmed the basic features. This approach can realize optimizing and enhancing the performance of a long-lived transaction. We regard this approach applicable even to the modernized scalable cloud environments.

Automatic Transaction Compensation for Reliable Grid Applications

As grid technology is expanding from scientific computing to business applications, service oriented grid computing is aimed at providing reliable services for users and hiding complexity of service processes from them. The grid services for coordinating long-lived transactions that occur in business applications play an important role in reliable grid applications. In this paper, the grid transaction service (GridTS) is proposed for dealing with long-lived business transactions. We present a compensation-based long-lived transaction coordination algorithm that enables users to select results from committed sub-transactions. Unlike other long-lived transaction models that require application programmers to develop corresponding compensating transactions, GridTS can automatically generate compensating transactions on execution of a long-lived grid transaction. The simulation result has demonstrated the feasibility of GridTS and effectiveness of the corresponding algorithm.

Performance analysis of long-lived transaction processing systems with rollbacks and aborts

Increasing the parallelism in transaction processing and maintaining data consistency appear to be two conflicting goals in designing distributed database systems (DDBSs). This problem is especially difficult if the DDBS is serving long-lived transactions (LLTs). A special case of LLTs, called sagas, has been introduced that addresses this problem. A DDBS with sagas provides high parallelism to transactions by allowing sagas to release their locks as early as possible. However, it is also subject to an overhead, due to the efforts needed to restore data consistency in the case of failure. We conduct a series of simulation studies to compare the performance of LLT systems with and without saga implementation in a faulty environment. The studies show that saga systems outperform their nonsaga counterparts under most of conditions, including heavy failure cases. We thus propose an analytical queuing model to investigate the performance behavior of saga systems. The development of this analytical model assists us to quantitatively study the performance penalty of a saga implementation due to the failure recovery overhead. Furthermore, the analytical solution can be used by system administrators to fine-tune the performance of a saga system. This analytical model captures the primary aspects of a saga system, namely data locking, resource contention and failure recovery. Due to the complicated nature of the analytical modeling, we solve the model approximately for various performance metrics using decomposition methods, and validate the accuracy of the analytical results via simulations.

An adaptive checkpointing scheme for distributed databases with mixed types of transactions

A checkpointing algorithm that is noninterfering with transaction processing is presented. It prevents the well-known domino effect and saves the intermediate results of a long-lived transaction in an adaptive manner, managing effectively both short- and long-lived transactions in the system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>