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H. F. Wedde, S. Böhm und W. Freund
Adaptive Concurrency Control in Safety-Critical Real-Time Systems
IFAC Conference on New Technologies in Computer Control 2001 (NTCC’01), Hong Kong, ROC, 2001-11


We present a novel transaction model for distributed safety-critical real- time applications in that transactions become increasingly critical under failures of subsequent incarnations. When a transaction-dependent criticality threshold has been reached the transaction is considered essentially critical or hard, i.e. the deadline has to be met lest the system is doomed to be in a disastrous state. The corresponding adaptive measures to provide that potentially all hard deadlines are met (criticality, sensitivity), i.e. that the system survives, are described in detail. As the major contribution of this paper we propose adaptive techniques for distributed concurrency control under safety-critical real-time requirements. In particular, we refrain from traditional features like roll-back because they are too costly. Also, tasks constituting a transaction will only be invoked whenever the needed data objects are no longer similar to their previous versions. We demonstrate how all features could be associated with available concurrency control algorithms, by modifying a recent concurrency control algorithm (OQPL) in a three-step procedure. We report on extensive distributed experiments.