Bounded Concurrent Time - Stamp Systems Are

Danny Dolev Concurrent time stamping is at the heart of solu tions to some of the most fundamental problems in distributed computing. Based on concurrent time-stamp-systems, elegant and simple solu tions to core problems such as fcf,-mutual exclusion, construction of a multi-reader-multi writer atomic register. probabilistic consensus,.. were developed. Unfortunmely, the only known implementation of a concurrent time stamp sys tem has been theoretically unsatisfying since it requires unbounded size time-stamps, in other words, unbounded memory. Not knowing if bounded concurrent-time-stamp-systems are at all constructible, researchers were led to con structing complicated problem-specific solutions to replace the simple unbounded ones. In this work for the first time, a bounded iruplemen tation of a concurrent-time-stamp-system is pre sented. It provides a modular unbounded-tobounded transformation of the simple unbounded solutions to prob1err such as aboveIt al lows solutions to two formerly open problems, the bounded-probabilistic-consensus problem of AbrahamBon [A88] and the fifo-t-exclusion prob 1BM Almaden Rearch Center and Hebrew Univer sity Jerusalem. ‘Hebrew University, Jerusalem. Supported by a Lib nitz Foundation Scholarship and Israeli Connntmications Ministry Award. Currently visiting the TDS group at MIT. supported by NSF coniract no CCR-S6]1442, by ONR contract no N0014-8S-K-0168. by DARP.1 contract no NJOt4-S3-K-Ol25. and a special grant fron [Bk!. Parts of this research were aJ,o conducted while the author was visiting AT&T Bell Laboratories and IBM Airnaden Research C-enter. Nir Shavitt 1cm of IFLBB85J, and a more efficient construc tion of mrmw atomic registers.