Flexible and Efficient In-Vivo Enhancement for Grid Applications

In a grid application, some requirements may change while the execution is in progress. This paper presents in-vivo enhancement--updating running grid applications to facilitate their perfective maintenance. Because applications in this domain are not only typically long-running, but also time-consuming to deploy, we propose a dynamic update technique that can change a running application flexibly and efficiently. Specifically, this paper presents a novel technique for dynamically updating grid applications deployed on the Java Virtual Machine (JVM). Our technique overcomes constraints of JVM HotSwap, a facility for replacing classes at runtime. While HotSwap precludes the programmer from adding new methods and fields, changing the signatures of existing methods, and has no support for transferring state between old and new objects, our approach effectively removes these constraints by rewriting program bytecode. Further, the rewritten programs incur only minimal performance overhead (less than 2% on average). We demonstrate the efficiency and extensibility of our approach through micro and macro benchmarks, as well as through a case study of dynamically updating a parallel bioinformatics application.