关键词：
Dynamic software updating
JVM
Lazy updating
Low disruption
摘要：
Context: In-use software systems are destined to change in order to fix bugs or add new features. Shutting down a running system before updating it is a normal practice, but the service unavailability can be annoying and sometimes unacceptable. Dynamic software updating (DSU) migrates a running software system to a new version without stopping it. State-of-the-art Java DSU systems are unsatisfactory as they may cause a non-negligible system pause during updating. Objective: In this paper we present Javelus, a Java HotSpot VM-based Java DSU system with very short pausing time. Method: Instead of updating everything at once when the running application is suspended, Javelus only updates the changed code during the suspension, and migrates stale objects on-demand after the application is resumed. With a careful design this lazy approach neither sacrifices the update flexibility nor introduces unnecessary object validity checks or access indirections. Results: Evaluation experiments show that Javelus can reduce the updating pausing time by one to two orders of magnitude without introducing observable overheads before and after the dynamic updating. Conclusion: Our experience with Javelus indicates that low-disruptive and type-safe dynamic updating of Java applications can be practically achieved with a lazy updating approach. (C) 2014 Elsevier B.V. All rights reserved.
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中文科技期刊
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