Linear space bootstrap communication schemes

Consider a system of n processes with ids that are drawn from a large space. How can these n processes communicate to solve a problem? It is shown that linear number of Multi-Writer Multi-Reader (MWMR) registers are sufficient to solve any read-write wait-free solvable problem and needed to solve some read-write wait-free solvable problem. This contrasts with the existing possible solution borrowed from adaptive algorithms that require Θ ( n 3 / 2 ) MWMR registers. To obtain the sufficiency result, the paper shows how the processes can non-blocking emulate a system of n Single-Writer Multi-Reader (SWMR) registers on top of n Multi-Writer Multi-Reader (MWMR) registers. For the necessity result, it shows it is impossible to do such an emulation with n − 1 MWMR registers. The paper also presents a wait-free emulation, using 2 n − 1 rather than just n registers. The emulation can be used to solve an infinite sequence of tasks that are sequentially dependent (processes need the previous task's outputs in order to proceed to the next task). A non-blocking emulation cannot be used in this case, because it might starve a process forever.

Authors

• Carole Delporte-Gallet
• Hugues Fauconnier
• Eli Gafni
• Sergio Rajsbaum

Keywords

• Shared memory
• Read/write registers
• Distributed algorithms
• Wait-free computing
• Space complexity
• Renaming