%T Rain VM: Portable Concurrency through Managing Code %A Neil C.C. Brown %E Peter H. Welch, Jon Kerridge, Frederick R. M. Barnes %B Communicating Process Architectures 2006 %X A long\-running recent trend in computer programming is the growth in popularity of virtual machines. However, few have included good support for concurrency \- a natural mechanism in the Rain programming language. This paper details the design and implementation of a secure virtual machine with support for concurrency, which enables portability of concurrent programs. Possible implementation ideas of many\-to\-many threading models for the virtual machine kernel are discussed, and initial benchmarks are presented. The results show that while the virtual machine is slow for standard computation, it is much quicker at running communication\-heavy concurrent code \- within an order of magnitude of the same native code.