We present a novel and portable threads-based system for concurrent applications on shared- and distributed-memory environments. The Ariadne system provides stateful user-space threads that can be very effective in medium to coarse grained applications. The interface is the same for uniprocessors and multiprocessors. Sequential programs are readily converted into parallel programs for shared or distributed memory, with low development effort. Ariadne supports the development of customized schedulers, and offers a thread migration capability in distributed environments. Scheduling of computations at the threads level enables both task- and data-driven executions. Thread migration is a useful feature which turns remote memory accesses into local accesses, enables load-balancing and simplifies program development. Ariadne employs a unique runtime stack rewriting mechanism to migrate threads between homogeneous processors. Ariadne currently runs on the SPARC (SunOS 4.x, SunOS 5.x), Sequent Symmetry, Intel Paragon, Silicon Graphics IRIX and IBM RS/6000 environments. We present some examples of Ariadne programs, along with performance measurements. © 1998 John Wiley & Sons, Ltd.

We present results on the experimental design and development of a Connectionless, Lightweight, and Multiway (CLAM) communications environment. The system provides efficient and scalable multiprotocol support for distributed applications that use multimodal data. We present motivation behind design decisions for the CLAM system, and describe two simple, but effective scheduling algorithms for the simultaneous support of multiple, threads-based user-space protocols. One algorithm is readily portable to shared-memory multiprocessors, and enables two or more protocols to coexist within an OS-level process. We present experimental results on the performance of both algorithms.

Threads exhibit a simply expressed and powerful form of concurrency, easily exploitable in applications that run on both uni- and multi-processors, shared- and distributed-memory systems. This paper presents the design and implementation of Ariadne: a layered, C-based software architecture for multi-threaded distributed computing on a variety of platforms. Ariadne is a portable user-space threads system that runs on shared- and distributed-memory multiprocessors. Thread-migration is supported at the application level in homogeneous environments (e.g., networks of SPARCs and Sequent Symmetrys, Intel hypercubes). Threads may migrate between processes to access remote data, preserving locality of reference for computations with a dynamic data space. Ariadne can be tuned to specific applications through a customization layer. Support is provided for scheduling via a built-in or application-specific scheduler, and interfacing with any communications library. Ariadne currently runs on the SPARC (SunOS 4.x and SunOS 5.x), Sequent Symmetry, Intel i860, Silicon Graphics workstation (IRIX), and IBM RS/6000 environments. We present simple performance benchmarks comparing Ariadne to threads libraries in the SunOS 4.x and SunOS 5.x systems.