A distributed Java Virtual Machine (DJVM) running across multiple cluster nodes provides a true parallel execution environment for performing multi-threaded Java applications in a distributed environment. While there are several prototypes of DJVMs ever implemented, the approach of using Just-in-Time compiler (JIT) in a DJVM was little explored in the literature. Most existing DJVMs, while supporting some forms of migratability, usually suffer from the slow Java interpreter execution and may not be efficient enough for solving computation-intensive problems. In this paper we present JESSICA2, new DJVM running in JIT mode that can run multi-threaded Java applications transparently on clusters with an single system image (SSI) illusion. JESSICA2 implemented a cluster-aware Java execution engine, which allows Java threads to be migrated in JIT mode for purpose of dynamic load balancing. In this paper, we explain the issues surrounding thread migration in a JIT compilation environment and show that it can greatly help DJVM for achieving high performance. In addition, JESSICA2 achieves SSI by hiding all the distributed object accesses with a global object space (GOS), which frees the user from caring about the physical location on which a Java thread is running. The object-oriented implementation of GOS satisfies the memory constrains in current Java Memory Model and effectively exploits the Java semantics to reduce the object access overheads in the distributed environments. An adaptive migrating-home protocol used in GOS is introduced. JESSICA2 has been implemented on an 8-node x86-based Linux clusters. Significant performance improvement over JESSICA was observed.