A NEW TRANSPARENT JAVA THREAD MIGRATION SYSTEM USING

Thread migration is to support the movement of threads across machine boundaries in a distributed computing environment. It can improve load balancing and the execution efficiency of multithreaded programs. In this paper, we introduce a new approach that employs the technique of Just-in-Time (JIT) recompilation to support transparent thread migration. With JIT recompilation, the native thread execution mode is preserved, and much of the space and time overheads of previous solutions based on code instrumentation can be eliminated. The new thread migration system is integrated into the JESSICA2 distributed JVM. The measured results show that our approach is beneficial to the overall system in supporting the transparent execution of Java applications on clusters

From the proceedings of ECAI'98, the 13th European Conference on Artificial Intelligence, Brighton, UK.

this paper we present a progressive-deepening model of structure-mapping that meets the real-time demands of both cognitive theories and practical systems. The model we describe is an elaboration of Sapper, a spreading-activation model of metaphor and analogy that has been demonstrated to possess the mapping competence of Falkenhainer et al.s SME the Structure-Mapping Engine, and Holyoak and Thagards ACME the Analogical Constraint Mapping Engine, while exhibiting superior tractability and run-time performance (empirical results are presented in Veale et al. 1996a,b; 1997). SME is a symbolic matcher for expressions in FOPC, whose interlocking nested predications form a forest- of-trees representation, while ACME is a connectionist model that views analogy as a process of constraint satisfaction. However, both models view complex nested predications as trees, wherein predicates act as internal nodes and objects act as leaves. As we shall show, this structural preference makes these models resistant to the advantages of progression-based search. 2. Constraints and Reactivity in StructureMapping The situated and dynamical nature of analogy and metaphor imposes a variety of real-time demands on the structure-mapping process. In particular, we distinguish three broad forms of contextual sensitivity to which the process may be required to react: Temporal constraints: The cognitive agent may impose a time limit on the structure-mapping process. In this case, the process must return the optimal, or near-optimal, mapping available in the given time. The agent should thus act in a bounded- optimal fashion (see Etzioni 1989). However, given the proven NP-Hardness of structure-mapping, and the need to use sub-optimal heuristics, the best ..