This Article 
   
 Share 
   
 Bibliographic References 
   
 Add to: 
 
Digg
Furl
Spurl
Blink
Simpy
Google
Del.icio.us
Y!MyWeb
 
 Search 
   
Time-Free and Timer-Based Assumptions Can Be Combined to Obtain Eventual Leadership
July 2006 (vol. 17 no. 7)
pp. 656-666
ASCII Text
x 
 
Achour Mostefaoui, Michel Raynal, Corentin Travers, "Time-Free and Timer-Based Assumptions Can Be Combined to Obtain Eventual Leadership," IEEE Transactions on Parallel and Distributed Systems, vol. 17, no. 7, pp. 656-666, July, 2006.
 
 
BibTex
x
 
@article{ 10.1109/TPDS.2006.95,
author = {Achour Mostefaoui and Michel Raynal and Corentin Travers},
title = {Time-Free and Timer-Based Assumptions Can Be Combined to Obtain Eventual Leadership},
journal ={IEEE Transactions on Parallel and Distributed Systems},
volume = {17},
number = {7},
issn = {1045-9219},
year = {2006},
pages = {656-666},
doi = {http://doi.ieeecomputersociety.org/10.1109/TPDS.2006.95},
publisher = {IEEE Computer Society},
address = {Los Alamitos, CA, USA},
}
 
 
RefWorks Procite/RefMan/Endnote
x 
 
TY - JOUR
JO - IEEE Transactions on Parallel and Distributed Systems
TI - Time-Free and Timer-Based Assumptions Can Be Combined to Obtain Eventual Leadership
IS - 7
SN - 1045-9219
SP656
EP666
EPD - 656-666
A1 - Achour Mostefaoui,
A1 - Michel Raynal,
A1 - Corentin Travers,
PY - 2006
KW - Asynchronous system
KW - distributed algorithm
KW - fault tolerance
KW - hybrid protocol
KW - leader election
KW - process crash
KW - time-free assumption
KW - timer-based assumption.
VL - 17
JA - IEEE Transactions on Parallel and Distributed Systems
ER -
 

Abstract—Leader-based protocols rest on a primitive able to provide the processes with the same unique leader. Such protocols are very common in distributed computing to solve synchronization or coordination problems. Unfortunately, providing such a primitive is far from being trivial in asynchronous distributed systems prone to process crashes. (It is even impossible in fault-prone purely asynchronous systems.) To circumvent this difficulty, several protocols have been proposed that build a leader facility on top of an asynchronous distributed system enriched with additional assumptions. The protocols proposed so far consider either additional assumptions based on synchrony or additional assumptions on the pattern of the messages that are exchanged. Considering systems with n processes and up to f process crashes, 1\leq f , this paper investigates the combination of a time-free assumption on the message pattern with a synchrony assumption on process speed and message delay. It shows that both types of assumptions can be combined to obtain a hybrid eventual leader protocol benefiting from the best of both worlds. This combined assumption considers a star communication structure involving f+1 processes. Its noteworthy feature lies in the level of combination of both types of assumption that is "as fine as possible” in the sense that each of the f channels of the star has to satisfy a property independently of the property satisfied by each of the f-1 other channels (the f channels do not have to satisfy the same assumption). More precisely, this combined assumption is the following: There is a correct process p (center of the star) and a set Q of f processes q (p \notin Q) such that, eventually, either 1) each time it broadcasts a query, q receives a response from p among the (n-f) first responses to that query, or 2) the channel from p to q is timely. (The processes in the set Q can crash.) A surprisingly simple eventual leader protocol based on this fine grain hybrid assumption is proposed and proved correct. An improvement is also presented.

[1] M.K. Aguilera, C. Delporte-Gallet, H. Fauconnier, and S. Toueg, “On Implementing Omega with Weak Reliability and Synchrony Assumptions,” Proc. 22nd ACM Symp. Principles of Distributed Computing (PODC '03), pp. 306-314, 2003.
[2] M.K. Aguilera, C. Delporte-Gallet, H. Fauconnier, and S. Toueg, “Communication-Efficient Leader Election and Consensus with Limited Link Synchrony,” Proc. 23rd ACM Symp. Principles of Distributed Computing (PODC '04), pp. 328-337, 2004.
[3] E. Anceaume, A. Fernandez, A. Mostefaoui, G. Neiger, and M. Raynal, “Necessary and Sufficient Condition for Transforming Limited Accuracy Failure Detectors,” J. Computer and System Sciences, vol. 68, pp. 123-133, 2004.
[4] T.D. Chandra and S. Toueg, “Unreliable Failure Detectors for Reliable Distributed Systems,” J. ACM, vol. 43, no. 2, pp. 225-267, 1996.
[5] T.D. Chandra, V. Hadzilacos, and S. Toueg, “The Weakest Failure Detector for Solving Consensus,” J. ACM, vol. 43, no. 4, pp. 685-722, 1996.
[6] F. Chu, “Reducing $\Omega$ to $\diamond {\cal {W}}$ ,” Information Processing Letters, vol. 76, no. 6, pp. 293-298, 1998.
[7] F. Cristian and C. Fetzer, “The Timed Asynchronous System Model,” IEEE Trans. Parallel and Distributed Systems, vol. 10, no. 6, pp. 642-657, June 1999.
[8] C. Dwork, N. Lynch, and L. Stockmeyer, “Consensus in the Presence of Partial Synchrony,” J. ACM, vol. 35, no. 2, pp. 288-323, 1988.
[9] M.J. Fischer, N. Lynch, and M.S. Paterson, “Impossibility of Distributed Consensus with One Faulty Process,” J. ACM, vol. 32, no. 2, pp. 374-382, 1985.
[10] R. Guerraoui, “Indulgent Algorithms,” Proc. 19th ACM Symp. Principles of Distributed Computing, (PODC '00), pp. 289-298, 2000.
[11] R. Guerraoui and M. Raynal, “The Information Structure of Indulgent Consensus,” IEEE Trans. Computers, vol. 53, no. 4, pp. 453-466, Apr. 2004.
[12] M. Hutle, “Omega in Sparse Networks,” Fast Abstracts, Proc. 10th IEEE Int'l Pacific Rim Dependable Computing Symp. (PRDC '04), 2004.
[13] L. Lamport, “The Part-Time Parliament,” ACM Trans. Computer Systems, vol. 16, no. 2, pp. 133-169, 1998.
[14] M. Larrea, A. Fernández, and S. Arévalo, “Optimal Implementation of the Weakest Failure Detector for Solving Consensus,” Proc. 19th Symp. Reliable Distributed Systems (SRDS '00), pp. 52-60, 2000.
[15] A. Mostefaoui, E. Mourgaya, and M. Raynal, “Asynchronous Implementation of Failure Detectors,” Proc. Int'l IEEE Conf. Dependable Systems and Networks (DSN '03), pp. 351-360, 2003.
[16] A. Mostefaoui and M. Raynal, “Low-Cost Consensus-Based Atomic Broadcast,” Proc. Seventh IEEE Pacific Rim Int'l Symp. Dependable Computing (PRDC '00), pp. 45-52, 2000.
[17] A. Mostefaoui and M. Raynal, “Leader-Based Consensus,” Parallel Processing Letters, vol. 11, no. 1, pp. 95-107, 2001.
[18] A. Mostefaoui, M. Raynal, and C. Travers, “Crash-Resilient Time-Free Eventual Leadership,” Proc. 23rd Symp. Reliable Distributed Systems (SRDS '04), pp. 208-217, 2004.
[19] F. Pedone and A. Schiper, “Handling Message Semantics with Generic Broadcast Protocols,” Distributed Computing, vol. 15, no. 2, pp. 97-107, 2002.
[20] D. Powell, “Failure Mode Assumptions and Assumption Coverage,” Proc. 22nd Int'l Symp. Fault-Tolerant Computing (FTCS-22), pp. 386-395, 1992.

Index Terms:
Asynchronous system, distributed algorithm, fault tolerance, hybrid protocol, leader election, process crash, time-free assumption, timer-based assumption.
Citation:
Achour Mostefaoui, Michel Raynal, Corentin Travers, "Time-Free and Timer-Based Assumptions Can Be Combined to Obtain Eventual Leadership," IEEE Transactions on Parallel and Distributed Systems, vol. 17, no. 7, pp. 656-666, July 2006, doi:10.1109/TPDS.2006.95
Usage of this product signifies your acceptance of the Terms of Use.