| Research Abstract |
In functional programming, evaluations of functional arguments are evaluated by eager evaluation or lazy evaluation, while in parallel evaluation of parallel functional programs there are "eager task creation" which is commonly used in parallel processing, and "lazy creation of concurrent tasks" which has been proposed by T. Ito (Head investigator of this project). The lazy creation of concurrent tasks is called "Steal-Help Evaluation" (SHE, in short), which creates processes only when idle processors are available and is known to be better than ETC (eager task creation) in achieving high-performance. The SHE is realized using a set of operations on the SST (Stealable Stack). Two unique interesting constructs "stealable" and "pdelay" are introduced incorporate the SHE into parallel language design. Moreover, we proposed and designed the SST Machine, which is a virtual parallel machine based on the SHE strategy. The SST machine library written in the C language is implemented to support
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easy and standardized implementation of the SHE strategy. The SST machine library is successfully used to realize an efficient parallel system of PaiLisp, which is a parallel Scheme with a rich set of concurrency constructs. including pcall, plet, pletrec, par-and, par-or, future, stealable. Note that the system is based on eager eavaluation of functional arguments and lazy creation of concurrent tasks. A compact kernel of PaiLisp, called PaiLisp-Kernel is derived under the ETC strategy and the SHE strategy. Also, a parallel functional language system based lazy evaluation of functional arguments and lazy creation of concurrent tasks (that is, SHE) has been designed and implemented. The resultant system has several good features and properties over the one based on eager evaluation and SHE. However, in order to realize a high-performance system based on lazy evaluation some efficient implementation techniques need to be developed as in eager evaluation systems. The reaearch revealed that the SHE strategy is reaally a nice technique to implement an efficient parallel system and the new construct "stealable" is a simple and efficient construct with a clean concurrency semantics and a wide applicability to various parallel languages. Also, the SST machine and its C library are useful in implementing an SHE-based parallel system. Less
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