G. Ricart and A. K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Comm. ACM, 24(1), 1981.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....for verifying non regular parameterized systems. All suggested methods have been successfully used to prove mutual exclusion of the Peterson algorithm for an arbitrary number of processes [Pet81] and termination of a termination detection algorithm extracted from Ricart and Agrawalas algorithm [RA81] Future Work It is left to study the relation ship between these methods. Is one stronger than the other or are they incomparable, and one works on some instances while the second works on other. In this paper we consider only safety properties. It is important to extend our methods to verify ....

G. Ricart and A.K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Comm. ACM, 24(1):9--17, 1981. Corr. ibid. 1981, p.581.

..... We conjecture that such a message is needed in order for the algorithm to get rid of the poor performance exhibited by CTP Ring1. A more formal treatment of this issue will be one of our future work. Finally, unlike Ricart and Agrawala s message passing algorithm for N process mutual exclusion [5], the sequence numbers used by the algorithms presented in the paper cannot be bounded within the range from x to x N 1. To see this, for example, consider CTP Ring1. Suppose that p i has initiated a request for X with a sequence number n. If no philosopher is interested in a di erent forum, ....

Ricart, G. and Agrawala, A. K.: `An optimal algorithm for mutual exclusion in computer networks,' CACM, Jan. 1981, 24(1), pp. 9-17. 14

....process has observed the content. Indeed, as we shall see shortly in Section 3, a symmetric and completely decentralized solution satisfying the three basic requirements mutual exclusion, bounded delay, and concurrent entering can be easily devised by modifying Ricart and Agrawala s algorithm [10] for n process mutual exclusion. This is not the case we have experienced in the shared memory model; the algorithm presented in [4] is somewhat complex and is not a straightforward adaption from existing algorithms for mutual exclusion. Nevertheless, one is easy to be deceived by this simple ....

....nature of the problem, an averagecase analysis is extremely complicated. Simulation studies [6] are therefore encouraged to provide some insight into the average case behavior of a proposed solution. 3 A Straightforward Decentralized Solution Recall that in Ricart and Agrawala s algorithm [10] for n process mutual exclusion, a process requiring entry to the critical section multicasts a request message to every other process, and enters the critical section only when all the other processes have replied to this request. To ensure mutual exclusion and bounded delay, each process ....

G. Ricart and A. K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. CACM, 24(1):9--17, January 1981.

....invocation. In the following sections we will see the concepts behind each group of algorithms. 3 Voting Based Algorithms The basic concept in these algorithms is to obtain permission from majority of nodes to enter critical section. One such algorithm is first given by Ricart and Agrawala [1]. In these algorithms certain assumptions are made on the underlying communication network. Assumptions made in [1] are ffl Communication Network is error free. ffl Transit times may vary. ffl Messages are not delivered in the order in which they are generated. In this algorithm the requests ....

....Algorithms The basic concept in these algorithms is to obtain permission from majority of nodes to enter critical section. One such algorithm is first given by Ricart and Agrawala [1] In these algorithms certain assumptions are made on the underlying communication network. Assumptions made in [1] are ffl Communication Network is error free. ffl Transit times may vary. ffl Messages are not delivered in the order in which they are generated. In this algorithm the requests are ordered by giving sequence numbers. Nodes are numbered and these numbers are used to break the ties between the ....

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Ricart, G., and Agrawala, A.K. An Optimal Algorithm for Mutual Exclusion in Computer Newtworks. Comm. ACM 24, 1 (Jan 1981), 9-17.

....sends a request message to each cell in . When a cell receives the request from ,if is not in search mode or is in search mode but s request has higher timestamp [15] than s, sends a reply message which appends the information about its used channels to ; otherwise, defers the reply (similar to [20]) After the borrower has received reply messages from cells in or the timer timeouts, the borrower computes the available channels and picks one according to the underlying channel selection algorithm. The borrower has to confirm the selected channel with the lenders, since a lender may assign ....

G. Ricart and A. K. Agrawal, "An optimal algorithm for mutual exclusion in computer networks," Commun. ACM, vol. 24, no. 1, Jan. 1981.

....The failure number of the algothm is kept at minimum. Moreover, the algorithm is simple to implement, and requires less storage and message overhead than existing algorithms. II. Previous Work Prakash, Shivaratri, and Singhal (PK) 8] proposed an algorithm based on deferral technique used in [9]. Choy and Singh (CS) 3] presented the algorithm that reduces the number of channel transfers in PK. Both PK and CS fall into the search category [4] since each MSS does not maintain the information about the channel being used by its neighbors. When a channel is needed (no available channels in ....

G. Ricart and A. K. Agrawala. An Optimal Algorithm for Mutual Exclusion in Computer Networks. In Communications of the ACM, 24(1):9-17, January 1981.

....problems. Recently, Banino, Kaiser, and Zimmermann [2] have developed a synchronization approach based on use of a shared broadcast channel. That work can be derived from our distributed semaphore implementation, although our implementation requires considerably fewer message broadcasts. In [17] a lower bound for the number of messages that must be exchanged to implement mutual exclusion in a distributed system is proved. We happily note that their solution can be viewed as an optimization of a distributed semaphore based solution to the critical section problem. Other implementations ....

RICART, G., ANO AGRAWALA, A.K. An optimal algorithm for mutual exclusion in computer networks. Commun. ACM 24, 1 (Jan. 1981), 9-17.

....ring model could become penalizing if the system is made up of many nodes some of which are inactive: the token continues to travel all around the ring and the time between two turns is wasted. For such a case, other studies have optimized the critical section management in distributed systems [Lam78, Agr81, Mae85, Nai87]. In cooperative work the number of sites is rather low. For example, it is not acceptable to edit a cooperative document with more than one twenty members. 35 33 21 15 12 11 O O O O O O The Token Structure 4 is inactive object with which there is an update or a request no object with ....

A.K. Agrawala and G. Ricart. An Optimal Algorithm for Mutual Exclusion in Computer Networks. Communication ACM, 24:9-17, 1981.

....give a token to each processor. It is not necessary to request the token. The token ring model could become penalizing if the system is made up of many nodes some of which are inactive. For such a case, other studies have optimized the critical section management in distributed systems [Lam78, Agr81, Mae85, Nai87] In cooperative work the number of sites is rather low. In this situation, we developed an algorithm which uses the token technique. But in our algorithm, the token is not a simple variable which is successively transmitted to each node of the ring, but a more complex data ....

A.K. Agrawala and G. Ricart. An Optimal Algorithm for Mutual Exclusion in Computer Networks. Communication ACM, 24:9-17, 1981.

....The problem requires that at most K nodes be in a critical section (CS) at any given time. The proposed algorithm achieves this using K tokens; only a process in possession of a token may enter the critical section. Although there has been extensive research on distributed 1 mutual exclusion [13, 18, 4, 11, 10, 16, 15, 2, 3, 5, 6, 9, 7, 12, 17], research on distributed K mutual exclusion (K 1) is limited [19, 20, 21, 22] Our approach for K mutual exclusion is derived by improving and extending the 1mutual exclusion algorithm by Trehel and Naimi [12] The proposed algorithm is compared with three other distributed K mutual exclusion ....

G. Ricart and A. K. Agrawala, "An optimal algorithm for mutual exclusion in computer networks," Comm. ACM, vol. 24, pp. 9--17, January 1981.

....The distributed algorithms of mutual exclusion are excellent illustrations of the genericity concept, since hosts arc connected among themselves and have to manage in a symmetrical manner (and fairly) their entry in the critical section. We briefly remind the Ricart and Agrawala s algorithm [18]. Each host has a counter initially set to n 1 (where n is the hosts number) and, when this counter reaches the zero value, the host may enter the critical section. Initially, the host broadcasts a request to all the others hosts. Then, it decrements its counter on receipt of each acknowledgment ....

G. Ricart, A.K. Agrawala, "An Optimal Algorithm for Mutual Exclusion in Computer Networks". Communications of the ACM, 24(1), 9-17.

....mutuelle. Les algorithmes rdpartis d exclusion mutuelle sont d excellentes illustrations du concept de gdndricitd, puisque des sites tous connectds entre eux doivent gdrer de manire symdtrique (et dquitable) leurs entrdes en section critique. Rappelons brivement ralgorithme de Ricart et Agrawala [14]. Chaque site dispose d un compteur initialisd h n 1 (oh nest le nombre de sites) et lorsque ce compteur atteint la valeur nulle le site peut entrer en section critique. Initialement le site diffuse une requate aux autres sites. Puis il ddcrdmente son compteur h chaque arrivde d un accusd de ....

G. Ricart, A.K. Agrawala, "An Optimal Algorithm for Mutual Exclusion in Computer Networks". Communications of the ACM, 24(1), 9-17.

....resources. Each instance of the resource (IP address) can be assigned to nodes in a mutually exclusive fashion. In the absence of a central server, a distributed mutual exclusion algorithm has to be employed. The proposed solution borrows from the mutual exclusion algorithm of Ricart and Agrawala [13]. However, the Ricart Agrawala algorithm needs to be augmented to be useful in the context of MANETs. This is due to the following differences between the system model assumed by the RicartAgrawala algorithm and the MANET system model: 1. The Ricart Agrawala algorithm assumes that message ....

G. Ricart and A. K. Agrawala, "An Optimal Algorithm for Mutual Exclusion in Computer Networks," Communications of the ACM, vol. 24, no. 1, pp. 9--17, January 1981.

....graybox stabilization. We present our method for designing graybox stabilization in Section 2.2. In Section 3, we present our local everywhere specification , Lspec, for TME. Then, in Section 4, we use our method to design the wrapper # . In Section 5, we show that Ricart Agrawala s TME program [11], and Lamport s TME program [10] satisfy Lspec, and hence # adds stabilization to both of them. We make concluding remarks in Section 6. For reasons of space, we relegate all proofs to the Appendix. 2 Graybox Design In this section, after some preliminary definitions that express both ....

....tune the wrapper to decrease the unnecessary repetitions of the request messages when the system is in the consistent states. 5 Reusability of the Wrapper for TME In this section, we present two well known everywhere implementations of Lspec, namely the mutual exclusion programs of Ricart Agrawala [11] and Lamport [10] It follows that the wrapper # renders both to be stabilizing tolerant to Lspec. 5.1 Ricart Agrawala s Program, RA ME The idea of RA ME is as follows. Whenever process # wants to enter the critical section, CS, it sends a timestamped request message to all the processes. #, upon ....

G. Ricart and A. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Communications of the ACM, 24(1):9--17, 1991.

....The next step is to design fault tolerance to VC applications using this faulttolerant RVC as a building block. To this end, we use the method described in Section 1.3. We give two illustrations of our method; the application in the rst illustration is Ricart and Agrawala s mutual exclusion [26], and in the second is Garg and Chase s transient predicate detector [13] To the best of our knowledge, in both cases, prior solutions have lacked bounded space and or stabilizing tolerance. 1.5 Outline of the Thesis In Chapter 2, we discuss the system model and de ne the RVC problem. In ....

....In Chapter 4, we design stabilizing fault tolerance for the bounded space RVC by exploiting its contract. In Chapters 5 and 6, we use 9 the bounded space and fault tolerant RVC to design bounded space and stabilizing fault tolerant versions for the mutual exclusion solution by Ricart Agrawala [26] and the transient predicate detector by Garg Chase [13] We make concluding remarks in Chapter 7. We relegate all proofs to the Appendix. 10 CHAPTER 2 PRELIMINARIES 2.1 System Model A program consists of a set of processes which communicate via message passing on interprocess channels. ....

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G. Ricart and A. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Communications of the ACM, 24(1):9-17, 1991.

.... k mutual exclusion algorithms have been proposed[6] 10] There are two paradigms for distributed mutual exclusion algorithms: the permissionbased and the token based ones [7] Raymond [6] proposed a permission based algorithm as an extension of Ricart and Agrawala s mutual exclusion algorithm[8]. Since a process wishing to enter a critical section sends a request message to each of the other processes, its message complexity is # n) Srimani and Reddy[10] proposed a token based algorithm as an extension of Suzuki and Kasami s algorithm[11] They use k tokens, and its message complexity ....

G. Ricart and A. K. Agrawala. An optimal algorithm for mutual exclusion in computer network. Communications of the ACM, 24(1):9--17, January 1981.

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G. Ricart and A. K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Comm. ACM, 24(1), 1981.

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G. Ricart and A. K. Agrawal, An optimal algorithm for mutual exclusion in computer networks, Comm. Assoc. Comput. Mach. 24 (1) (Jan. 1981), 9#17.

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G. Ricart and A. K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Commun. ACM, 24(1):9--17, 1981.

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G. Ricart and A. K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Commun. ACM, 24(1):9--17, 1981.

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G. Ricart and A. K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Communications of the ACM, 24(1):9--17, January 1981.

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G. Ricart and A. Agrawala "An Optimal Algorithm for Mutual Exclusion in Computer Networks" Comm.ACM 24(1)(Jan 1981), pp.9-17

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G. Ricart and A.K. Agrawala, "An optimal algorithm for mutual exclusion in computer networks," CACM, January 1981, 9--17.

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G. Ricart and A.K. Agrawala. An optimal algorithm for mutual exclusion in computer networks. Communications of the ACM, 24(1):9-17, 1981. 27

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Ricart, G. An optimal algorithm for mutual exclusion in computer networks. Comm. ACM 24, 1 (Jan. 1981), 5--19.

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