An asynchronous message-passing distributed algorithm for the global critical section problem

This paper considers the global $(l,k)$-CS problem which is the problem of controlling the system in such a way that, at least $l$ and at most $k$ processes must be in the CS at a time in the network. In this paper, a distributed solution is proposed in the asynchronous message-passing model. Our solution is a versatile composition method of algorithms for $l$-mutual inclusion and $k$-mutual exclusion. Its message complexity is $O(|Q|)$, where $|Q|$ is the maximum size for the quorum of a coterie used by the algorithm, which is typically $|Q| = \sqrt{n}$.Comment: This is a modified version of the conference paper in PDAA201

(h,k)-Arbiters for h-out-of-k mutual exclusion problem

Abstracth-Out-of-k mutual exclusion is a generalization of the 1-mutual exclusion problem, where there are k units of shared resources and each process requests h(1⩽h⩽k) units at the same time. Though k-arbiter has been shown to be a quorum-based solution to this problem, quorums in k-arbiter are much larger than those in the 1-coterie for 1-mutual exclusion. Thus, the algorithm based on k-arbiter needs many messages. This paper introduces the new notion that each request uses different quorums depending on the number of units of its request. Based on the notion, this paper defines two (h,k)-arbiters for h-out-of-k mutual exclusion: a uniform (h,k)-arbiter and a (k+1)-cube (h,k)-arbiter. The quorums in each (h,k)-arbiter are not larger than the ones in the corresponding k-arbiter; consequently, it is more efficient to use (h,k)-arbiters than the k-arbiters. A uniform (h,k)-arbiter is a generalization of the majority coterie for 1-mutual exclusion. A (k+1)-cube (h,k)-arbiter is a generalization of square grid coterie for 1-mutual exclusion

KETERSEDIAAN OPERASI JOIN DIPERLUAS KOTERI-k TAK-TERDOMINASI

Penelitian ini bertujuan menganalisis ketersediaan dari koteri-  mayoritas tak-terdominasi yang menggunakan operasi join diperluas yaitu penggabungkan koteri- ,  dan  masing-masing atas semesta  dan  dengan unsur tereliminasi , dimana  yang menghasilakan koteri-  tak-terdominasi  atas semesta . Metode penggabungan koteri-  mayoritas tak-terdominasi yang menggunakan operasi join diperluas menghasilkan koteri  atas . Hasil ketersediaan dari operasi join kemudian dibandingkan dengan ketersedian dengan menggunakan operasi join. Dari penelitian ini, menunjukkan bahwa ketersedian operasi join memberikan hasil yang lebih baik jika dibandingkan dengan ketersedian dari operasi join

NFK: a novel fault-tolerant K-mutual exclusion algorithm for mobile and opportunistic ad hoc networks

[EN] This paper presents a fault-tolerant algorithm ensuring multiple resources sharing in mobile ad hoc networks (MANETs) that is able to handle the known K-mutual exclusion problem in such mobile environments. The proposed algorithm relies on a token-based strategy, and requires information about resources and their use to be carried in routing protocol control messages. This way, our solution avoids any additional exchange of messages. Furthermore, experimental results show that it offers a fast response time. Moreover, we introduce a dual-layer fault-tolerance mechanism that tolerates the faults of several sites at the same time without affecting the well functioning of the system. Simulation results also evidence the high efficiency of our proposal, which achieves reduced overhead and response delay even in the presence of critical situations where multiple simultaneous faults occur.Allaoui, T.; Yagoubi, MB.; Kerrache, CA.; Tavares De Araujo Cesariny Calafate, CM. (2019). NFK: a novel fault-tolerant K-mutual exclusion algorithm for mobile and opportunistic ad hoc networks. International Journal of Information and Communication Technology. 15(2):176-197. https://doi.org/10.1504/IJICT.2019.102479S17619715

Section critique à entrées multiples tolérante aux fautes et utilisant des détecteurs de défaillances

Nous présentons dans cet article un nouvel algorithme tolérant aux fautes de K-exclusion mutuelle. Cet algorithme à permission est une extension de l'algorithme de Raymond [Ray89]. Il tolère n − 1 fautes et reste efficace malgré les défaillances. L'algorithme repose sur un détecteur de fautes non fiable. Une évaluation de performances montre l'efficacité de notre approche en présence de fautes

Permission-based fault tolerant mutual exclusion algorithm for mobile Ad Hoc networks

This study focuses on resolving the problem of mutual exclusion in mobile ad hoc networks. A Mobile Ad Hoc Network (MANET) is a wireless network without fixed infrastructure. Nodes are mobile and topology of MANET changes very frequently and unpredictably. Due to these limitations, conventional mutual exclusion algorithms presented for distributed systems (DS) are not applicable for MANETs unless they attach to a mechanism for dynamic changes in their topology. Algorithms for mutual exclusion in DS are categorized into two main classes including token-based and permission-based algorithms. Token-based algorithms depend on circulation of a specific message known as token. The owner of the token has priority for entering the critical section. Token may lose during communications, because of link failure or failure of token host. However, the processes for token-loss detection and token regeneration are very complicated and time-consuming. Token-based algorithms are generally non-fault-tolerant (although some mechanisms are utilized to increase their level of fault-tolerance) because of common problem of single token as a single point of failure. On the contrary, permission-based algorithms utilize the permission of multiple nodes to guarantee mutual exclusion. It yields to high traffic when number of nodes is high. Moreover, the number of message transmissions and energy consumption increase in MANET by increasing the number of mobile nodes accompanied in every decision making cycle. The purpose of this study is to introduce a method of managing the critical section,named as Ancestral, having higher fault-tolerance than token-based and fewer message transmissions and traffic rather that permission-based algorithms. This method makes a tradeoff between token-based and permission-based. It does not utilize any token, that is similar to permission-based, and the latest node having the critical section influences the entrance of the next node to the critical section, that is similar to token-based algorithms. The algorithm based on ancestral is named as DAD algorithms and increases the availability of fully connected network between 2.86 to 59.83% and decreases the number of message transmissions from 4j-2 to 3j messages (j as number of nodes in partition). This method is then utilized as the basis of dynamic ancestral mutual exclusion algorithm for MANET which is named as MDA. This algorithm is presented and evaluated for different scenarios of mobility of nodes, failure, load and number of nodes. The results of study show that MDA algorithm guarantees mutual exclusion,dead lock freedom and starvation freedom. It improves the availability of CS to minimum 154.94% and 113.36% for low load and high load of CS requests respectively compared to other permission-based lgorithm.Furthermore, it improves response time up to 90.69% for high load and 75.21% for low load of CS requests. It degrades the number of messages from n to 2 messages in the best case and from 3n/2 to n in the worst case. MDA algorithm is resilient to transient partitioning of network that is normally occurs due to failure of nodes or links

OPERASI JOIN KOTERI-k DIPERLUAS

Sebagaiman diketahui bahwa koteri-k merupakan perluasan dari definisi koteri yang dapat diterapkan masalah mutex-k. Pada mutex-k terdapat sebanyak k proses yang dapat mengakses sumber daya. Selain itu, kita juga mengenal koteri-k khusus yang disebut dengan koteri-k mayoritas dimana untuk setiap korumnya memiliki ukuran yang sama yang ditentukan dengan . Terdapat beberapa cara dalam penggabungan koter-ki salah satu diantaranya dan sudah tidak asing lagi yaitu operasi join yang merupakan suatu operasi yang digunakan dalam menggabungkan koteri-k mayoritas yang diperkenalkan oleh Neilsen dan Mizuno. Pada operasi join, terdapat salah satu sifat yang menyatakan bahwa jika  dan  tak-terdominasi maka  tak-terdominasi. Ternyata sifat tersebut tidak selamanya berlaku sehingga mengakibatkan koteri-k yang dihasilkan dari operasi join menjadi terdominasi.Tujuan dari penelitian ini yaitu memperkenalkan suatu cara baru dalam menggabungkan koteri-k mayoritas tak-terdominasi yang disebut dengan operasi join diperluas. Dimana operasi join diperluas ini adalah suatu operasi yang dikembangkan dari operasi join yang dibangun dengan cara menggabungkan dua koteri-k mayoritas  dan  yang memiliki ukuran korum yang sama masing-masing atas semesta tak-kosong  dan  dengan unsur tereliminasi , dimana  untuk membentuk  atas semesta tak-kosong . Hasil dari penelitian ini menunjukan bahwa untuk penggabungan dua koteri-k mayoritas tak-terdominasi dengan mengguankan operasi join diperluas akan selalu menghasilkan koteri-k tak-terdominasi dengan nilai k sebelum dan setelah dilakukan operasi penggabungan tidak mengalami perubahan

Exclusion and Object Tracking in a Network of Processes

This paper concerns two fundamental problems in distributed computing---mutual exclusion and mobile object tracking. For a variant of the mutual exclusion problem where the network topology is taken into account, all existing distributed solutions make use of tokens. It turns out that these token-based solutions for mutual exclusion can also be adapted for object tracking, as the token behaves very much like a mobile object. To handle objects with replication, we go further to consider the more general $k$-exclusion problem which has not been as well studied in a network setting. A strong fairness property for $k$-exclusion requires that a process trying to enter the critical section will eventually succeed even if \emph{up to} $k-1$ processes stay in the critical section indefinitely. We present a comparative survey of existing token-based mutual exclusion algorithms, which have provided much inspiration for later $k$-exclusion algorithms. We then propose two solutions to the $k$-exclusion problem, the second of which meets the strong fairness requirement. Fault-tolerance issues are also discussed along with the suggestion of a third algorithm that is also strongly fair. Performances of the three algorithms are compared by simulation. Finally, we show how the various exclusion algorithms can be adapted for tracking mobile objects