Rubah: DSU for Java on a stock JVM

Abstract This paper presents Rubah, the first dynamic software updating system for Java that: is portable, implemented via libraries and bytecode rewriting on top of a standard JVM; is efficient, imposing only 5-9% overhead on normal, steadystate execution; is flexible, allowing nearly arbitrary changes to classes between updates; and is non-disruptive, employing either a novel eager algorithm that transforms the program state with multiple threads, or a novel lazy algorithm that transforms objects as they are demanded, post-update. Requiring little programmer effort, Rubah has been used to dynamically update three substantial, long-running applications: the H2 database, the Voldemort key-value store, and the Jake2 implementation of the Quake 2 shooter game