Deadlock Avoidance Algorithm Research Articles

DBDAA: A real-time approach to Dynamic Banker’s Deadlock Avoidance Algorithm with optimized time complexity

Effective resource allocation is crucial in operating systems to prevent deadlocks, especially when resources are limited and non-shareable. Traditional methods like the Banker’s algorithm provide solutions but suffer from limitations such as static process handling, high time complexity, and a lack of real-time adaptability. To address these challenges, we propose the Dynamic Banker’s Deadlock Avoidance Algorithm (DBDAA). The DBDAA introduces real-time processing for safety checks, significantly improving system efficiency and reducing the risk of deadlocks. Unlike conventional methods, the DBDAA dynamically includes processes in safety checks, considerably decreasing the number of comparisons required to determine safe states. This optimization reduces the time complexity to O(n) in the best-case and O(nd) in the average and worst-case scenarios, compared to the O(n2d) complexity of the original Banker’s algorithm. The integration of real-time processing ensures that all processes can immediately engage in safety checks, improving system responsiveness and making the DBDAA suitable for dynamic and time-sensitive applications. Additionally, the DBDAA introduces a primary unsafe sequence mechanism that enhances the acceptability and efficiency of the algorithm by allowing processes to participate in safety checks repeatedly after a predetermined amount of system-defined time. Experimental comparisons with existing algorithms demonstrate the superiority of the DBDAA in terms of reduced safe state prediction time and increased efficiency, making it a robust solution for deadlock avoidance in real-time systems.

Deadlock prevention and multi agent path finding algorithm considering physical constraint for a massive fleet AGV system

This study introduces deadlock avoidance algorithms for Automated Guided Vehicles (AGVs) within warehouse fulfillment systems. Numerous AGVs are tasked with transporting requests to deliver shelves to workers stationed at various locations. The pathfinding challenge within such systems is identified as the Multi-Agent Pickup and Delivery (problem) and has been extensively explored in computer science and AI. Nevertheless, most prior research was conducted in environments that are discretized and allow circular movements of AGVs, potentially leading to deadlocks in real-world applications. Our proposed algorithm leverages a dynamic path block method and path reservation. Specifically, it limits movement to certain edges when AGVs navigate along reserved paths, while the remaining AGVs plan their routes using unrestricted edges. We show that our algorithm not only effectively prevents deadlocks but also scales well in environments with a high number of AGVs.

Deadlock Avoidance in Closed Guide-Path Based MultiAGV Systems

Automated guided vehicle (AGV) is widely used in transportation and distribution of materials. In the development of multi-AGV systems, how to handle deadlocks is a core issue. Most existing researches focus on open systems. Thus those results are not applicable in real-world systems. A few works have paid attention to closed systems recently, but the results are not flexible and generic enough. Therefore, an improved deadlock avoidance algorithm in closed guide-path system is proposed in this paper. The proposed algorithm is divided into an offline stage and an online stage. At the offline stage, the guide-path graph is processed to obtain useful information for the online stage. At the online stage, the algorithm assesses the safety of each resource allocation to ensure a deadlock-free operation. The computational complexity of the algorithm is shown to be <inline-formula> <tex-math notation="LaTeX">$O(|E|)$</tex-math> </inline-formula>, where <inline-formula> <tex-math notation="LaTeX">$E$</tex-math> </inline-formula> is the set of the edges in the guide-path graph. Based on the algorithm, an overall control strategy is also developed, and then implemented and tested in real systems. It is also compared with Banker&#x2019;s algorithm and its variants, the results of which show that the proposed algorithm has a better performance. <i>Note to Practitioners</i>&#x2014;Deadlock is a core issue in guide-path based multi-AGV systems. Once deadlock occurs, the whole system will collapse. This problem is more serious in closed systems, which is paid less attention to in literature. Current deadlock solutions are either too restrictive, resulting in inefficient resource utilization and poor flexibility, or computationally intensive and thus are unable to scale to large systems. To solve this problem, an improved deadlock avoidance algorithm with polynomial computational complexity is proposed in this paper, and it is more flexible than the Banker&#x2019;s algorithm and its variants. Furthermore, an overall control framework (i.e., including task assignment, path planning and real-time scheduling) is developed based on the deadlock avoidance algorithm, which keeps persistent operation of the considered system while still guaranteeing deadlock-free. However, in this overall control framework, the choice of path is not optimized with respect to travel distance and makespan, which is the direction of future research.

A Comparative Analysis of Deadlock Avoidance and Prevention Algorithms for Resource Provisioning in Intelligent Autonomous Transport Systems Over 6G Infrastructure

A Comparative Analysis of Deadlock Avoidance and Prevention Algorithms for Resource Provisioning in Intelligent Autonomous Transport Systems Over 6G Infrastructure

Deadlock detection, cooperative avoidance and recovery protocol for mixed autonomous vehicles in unstructured environment

AbstractDeadlock is an extreme traffic flow operational state during rush hours. Many literatures have studied autonomous vehicle coordination under the umbrella of deadlock‐free conditions. These researches either assume the trajectories are fixed or state spaces are discrete and limited on structured road spaces or don't consider the influence of human‐driven vehicles (HDV), which are not controllable from the system's viewpoint. This manuscript relaxes the above limitations and proposes a method to detect, avoid, and recover from deadlock for mixed autonomous vehicles flow. Firstly, two types of deadlocks, weak and strong , are defined based on deadlock properties. Next, two detection algorithms based on evasion distance propagation are proposed. After that, we present a cooperative control method to avoid deadlock based on chain‐spillover‐free and loop‐free strategies. If a deadlock has already happened, cooperative protocols based on re‐routing and backward‐forward strategies are designed. The proposed model is tested in Carla. The results show that the deadlocks can be detected 13 seconds earlier than their occurrence, and it takes about 6 seconds to unlock the existing deadlock. The results also show that with the proposed deadlock avoidance algorithm, the traffic throughput can be increased by 35.7%, and with the proposed deadlock recovery protocol, the traffic throughput can be increased by another 18%.

USING RANDOM EARLY DETECTION FOR ENHANCING NETWORK PERFORMANCE BY ADJUSTING LOWER THRESHOLDS AND AVERAGE QUEUE SIZES

In internet media, the created information will move to network nodes called the routing information, from one node to another based on the request made. When data loads increase in communication links, routers must be designed to supply reasonable data flow from resource to its target, to all network nodes. In case accessed data is heavy, routers can be deadlocked and reduce router's bandwidth which leads to increase packet loss. In order to sustainably transmit packets through such routers, they need to be designed and provided with effective deadlock avoidance algorithms. Formerly, these algorithms were used as Active queue management-AQM, Drop Tail algorithm (DT), and Random Early Detection-RED. This study suggests an innovative RED named LtRED (Lower threshold of RED) to address RED's shortcomings. Research results evaluated on NS2 showed the innovation LtRED algorithm was better than RED in terms of packet loss rate, average queue delay, and average throughput.

Geometric Zone-Control Algorithm for Collision and Deadlock Avoidance in AGV System

Geometric Zone-Control Algorithm for Collision and Deadlock Avoidance in AGV System

Deadlock Avoidance Algorithms for Recursion-Tree Modeled Requests in Parallel Executions

We present an extension of the bankers algorithm to resolve deadlock for programs whose resource-request graph can be modeled as a recursion tree for parallel execution. Our algorithm implements the bankers logic, with the key difference being that some properties of the tree are fully exploited to improve the resource utilization and safety check in deadlock avoidance. For an n-node tree modeled program making requests to m types of resources, our recursion-tree based algorithm can obtain a time complexity of O(mn loglogn) on average in safety check while reducing the conservativeness in resource utilization. We reap these benefits by proposing a concept of the resource critical tree and leverage it to localize the maximum claim associated with each node in the tree. To tackle the case when the tree model is not statically known, we relax the definition of a local maximum claim by sacrificing some resource utilization. With this trade-off, the algorithm can resolve the deadlock and achieve more efficient safety checks within time of O(m loglogn). Our empirical studies on a two-dimensional integration problem on sparse grids show that the proposed algorithms can reduce resource utilization conservativeness and improve avoidance performance by minimizing the number of safety checks.

A Robust Control Approach to Automated Manufacturing Systems Allowing Multitype and Multiquantity of Resources With Petri Nets

Up to now, the supervision and control of deadlock-free resource allocation has received considerable attention, particularly regarding their deadlock problems. To date, most solutions have supposed that allocated resources never fail. However, this is quite the opposite in reality since some resources may fail unexpectedly. A robust system should be resilient to such failures. In this paper, resources are divided into reliable ones and unreliable ones. On the basis of the deadlock avoidance algorithm which is proposed for the problem of deadlocks, we propose a robust control algorithm in the paradigm of systems of sequential systems with shared resources, which can acquire and release resources in a multitype and multiquantity way. It is validated to be a polynomially complex robust control algorithm by the distributivity analysis. Finally, experimental results show that the proposed approaches are effective as well as efficient in response to resource failures.

A Robust Control Approach to Automated Manufacturing Systems Combining Absorbing and Distributing Characteristics

The subject of deadlock control for automated manufacturing systems has been extensively studied in the past several years. For most of them, researchers have supposed that shared and dedicated resources never fail. As any manufacturing practitioner knows, resource failures, e.g., defective parts, faulty sensors, blurred signals, and broken actuators, are a common problem. Hence, the robust supervision and control for a system with unreliable resources is necessary. In our previous work, we proposed a robustness intensification algorithm based on a deadlock avoidance algorithm to ensure that processes not requiring unreliable resources can operate smoothly. In this article, a new robust method, which combines the advantages of absorbing policies and distributing policies with the aid of critical regions, is developed. It includes two algorithms, i.e., a robustness algorithm for processes not requiring unreliable resources and an intensification algorithm for processes requiring unreliable resources. Compared with existing absorbing and distributing policies, the new robust method can increase the production rate while decrease the algorithm complexity for a system allowing flexible routes apart from each process stage acquiring more than one type of resources.

Constructing the closed-form solution of control-related states real-time information for insufficient k-th order systems with one non-sharing resource to realize dynamic modeling large TNCS systems of petri nets

ABSTRACTSince the contribution from the closed-form solution (CFS) of the number of control-related states (CRSs) of the variant k-th order system can enumerate the number of each type of CRS in real time, we can apply this real-time information to enhance the capability for dynamic modeling of such systems. For example, allocating a non-sharing waiting dummy resource (known as a deadlock thread-holder [DTH]) in each forbidden substate at that location will increase the maximum number of reachable states that can be derived using a CFS in real time. We can thus avoid the occurrence of deadlock without implementing an additional controller. To extend this capability to model a k-th order system with one non-sharing circle subnet allocated at the top position of the left-hand process (denoted as a top non-sharing circle subnet [TNCS] k-th order system) by Petri net (PN), which is the fundamental manufacturing model for different products sharing common parts, this paper extends the existing research on CFS for PNs to an insufficient k-th order system, which is the essential element for a TNCS system with one non-sharing resource. The proposed deadlock avoidance algorithm can be employed to realize the allocation of dynamic non-sharing processes.

Ten Diverse Formal Models for a CBTC Automatic Train Supervision System

Communications-based Train Control (CBTC) systems are metro signalling platforms, which coordinate and protect the movements of trains within the tracks of a station, and between different stations. In CBTC platforms, a prominent role is played by the Automatic Train Supervision (ATS) system, which automatically dispatches and routes trains within the metro network. Among the various functions, an ATS needs to avoid deadlock situations, i.e., cases in which a group of trains block each other. In the context of a technology transfer study, we designed an algorithm for deadlock avoidance in train scheduling. In this paper, we present a case study in which the algorithm has been applied. The case study has been encoded using ten different formal verification environments, namely UMC, SPIN, NuSMV/nuXmv, mCRL2, CPN Tools, FDR4, CADP, TLA+, UPPAAL and ProB. Based on our experience, we observe commonalities and differences among the modelling languages considered, and we highlight the impact of the specific characteristics of each language on the presented models.

Reliable Resource Provisioning Using Bankers’ Deadlock Avoidance Algorithm in MEC for Industrial IoT

Multi-access edge computing (MEC) is a new 5G enabling technology proposed to reduce latency by bringing cloud computing capability closer to IoT and mobile device users. MEC may be prone to unreliable communication as a result of deadlock during resource provisioning. Deadlock may occur due to a huge number of devices contending for a limited amount of resources if adequate measures are not put in place. It is crucial to eradicate deadlock while scheduling and provisioning of resources on MEC to achieve highly reliable and available system. In this paper, a deadlock avoidance resource provisioning algorithm is proposed for Industrial IoT devices using MEC platforms to ensure the higher reliability of network interactions. The proposed scheme incorporates a banker’s resource-request algorithm using software-defined networking to reduce communication overhead. Simulation Results have shown that system deadlock can be prevented by applying the proposed algorithm which ultimately leads to a more reliable network interaction between mobile stations and MEC platforms.

Implementation of Banker’s Algorithm Using Dynamic Modified Approach

Banker’s algorithm referred to as resource allocation and deadlock avoidance algorithm that checks for the safety by simulating the allocation of predetermined maximum possible of resources and makes the system into s-state by checking the possible deadlock conditions for all other pending processes. It needs to know how much of each resource a process could possibly request. Number of processes are static in algorithm, but in most of system processes varies dynamically and no additional process will be started while it is in execution. The number of resources are not allow to go down while it is in execution. In this research an approach for Dynamic Banker's algorithm is proposed which allows the number of resources to be changed at runtime that prevents the system to fall in unsafe state. It also give details about all the resources and processes that which one require resources and in what quantity. This also allocates the resource automatically to the stopped process for the execution and will always give the appropriate safe sequence for the given processes.

Deadlock avoidance in parallel programs with futures: why parallel tasks should not wait for strangers

Futures are an elegant approach to expressing parallelism in functional programs. However, combining futures with imperative programming (as in C++ or in Java) can lead to pernicious bugs in the form of data races and deadlocks, as a consequence of uncontrolled data flow through mutable shared memory. In this paper we introduce the Known Joins (KJ) property for parallel programs with futures, and relate it to the Deadlock Freedom (DF) and the Data-Race Freedom (DRF) properties. Our paper offers two key theoretical results: 1) DRF implies KJ, and 2) KJ implies DF. These results show that data-race freedom is sufficient to guarantee deadlock freedom in programs with futures that only manipulate unsynchronized shared variables. To the best of our knowledge, these are the first theoretical results to establish sufficient conditions for deadlock freedom in imperative parallel programs with futures, and to characterize the subset of data races that can trigger deadlocks (those that violate the KJ property). From result 2), we developed a tool that avoids deadlocks in linear time and space when KJ holds, i.e., when there are no data races among references to futures. When KJ fails, the tool reports the data race and optionally falls back to a standard deadlock avoidance algorithm by cycle detection. Our tool verified a dataset of ∼2,300 student’s homework solutions and found one deadlocked program. The performance results obtained from our tool are very encouraging: a maximum slowdown of 1.06× on a 16-core machine, always outperforming deadlock avoidance via cycle-detection. Proofs of the two main results were formalized using the Coq proof assistant.

Collision and Deadlock Avoidance in Multirobot Systems: A Distributed Approach

Collision avoidance is a critical problem in motion planning and control of multirobot systems. Moreover, it may induce deadlocks during the procedure to avoid collisions. In this paper, we study the motion control of multirobot systems where each robot has its own predetermined and closed path to execute persistent motion. We propose a real-time and distributed algorithm for both collision and deadlock avoidance by repeatedly stopping and resuming robots. The motion of each robot is first modeled as a labeled transition system, and then controlled by a distributed algorithm to avoid collisions and deadlocks. Each robot can execute the algorithm autonomously and real-timely by checking whether its succeeding state is occupied and whether the one-step move can cause deadlocks. Performance analysis of the proposed algorithm is also conducted. The conclusion is that the algorithm is not only practically operative but also maximally permissive. A set of simulations for a system with four robots are carried out in MATLAB. The results also validate the effectiveness of our algorithm.

Deadlock Avoidance Based on Graph Theory

Deadlock Avoidance remains to be a significant aspect of deadlock research. Modeling approaches based on Graph Theory provide effective strategy to solve this problem. We built avoidance model of directed graph and adjacent matrix via resource allocation graph, proposed three improved algorithm for deadlock avoidance and discussed the implementation of the program. The topology analyze of matrix storage information indicates entire optimization utilization results though certain key vertices and edges, this model verified by the banker’s algorithm and Petri net finally.

Deadlock Avoidance and Detection in Railway Simulation Systems

Avoiding or preventing deadlocks in simulation tools for train scheduling remains a critical issue, especially when combined with the objective of minimization (e.g., the travel times of the trains). The deadlock avoidance and detection problem is revisited, and a new deadlock avoidance algorithm, called DEADAALG, is proposed based on a resource reservation mechanism. The DEADAALG algorithm is proved to be exact; that is, it either detects an unavoidable deadlock resulting from the input data or provides train scheduling free of deadlocks with the scheduling algorithm SIMTRAS. Moreover, it is shown that SIMTRAS is a polynomial time algorithm with an O(|S|&amp;Middot;|T|2 log |T|) time complexity, where T is the set of trains and S is the set of sections in the railway topo logy. Numerical experiments are conducted on Canada's Vancouver–Calgary single-track corridor of Canadian Pacific Railway Limited. Then it is shown that SIMTRAS is efficient and provides schedules of a quality that is comparable with that of an exact optimization algorithm in tens of seconds for up to 30 trains/day over a planning period of 60 days.

Petri Net Decomposition Approach for Dispatching and Conflict-Free Routing of Bidirectional Automated Guided Vehicle Systems

In this paper, we address a Petri net decomposition approach for simultaneous dispatching and conflict-free routing for bidirectional automated guided vehicle (AGV) systems in dynamic environments. To solve the dynamic problem, static problems for finding near-optimal dispatching and conflict-free routing are solved each time when transportation requests are given. The static problem is converted to an optimal firing sequence problem for a timed Petri net. A Petri net decomposition approach is applied to solve the problem efficiently. In the algorithm, the entire Petri net is decomposed into task and AGV subnets. The penalty function method is used to derive a solution for all subnets. A deadlock avoidance method is embedded in the proposed methodology to ensure the feasibility and the quality of the solution. Computational results show that the proposed method with a deadlock avoidance algorithm efficiently maximizes the throughput for dynamic situations.

Deadlock avoidance algorithm for flexible manufacturing systems by calculating effective free space of circuits†

Modern flexible manufacturing systems (FMS) are highly automated and flexible in which raw parts of various types are processed concurrently. Deadlock issue arises easily in these systems due to shared equipment usage and high production flexibility. It was indicated in Wysk et al . (Wysk, R., Yang, N. and Joshi, S., Detection of deadlocks in flexible manufacturing cells. IEEE Trans. Rob. Auto., 1991, 7, 853–859.) that when a manufacturing system is modelled by a digraph, existence of circuits in such a graph is a necessary condition for deadlock. Deadlock avoidance for systems with free choice in part routing has been well studied in the Petri net formalism, however, we have not found that it has been studied systematically in the digraph formalism. Because of choices introduced, part flow dynamics become much more complex. Based on our previous work Zhang et al . (Zhang, W., Judd, R.P. and Paul P., Evaluating order of circuits for deadlock avoidance in a flexible manufacturing system. Int. J. Prod. Res., 2006, 44, 5247–5259.), this paper presents a deadlock avoidance algorithm for FMS, which allows free choices in part routing by calculation of effective free space of circuits of the digraph model. The algorithm is highly permissive since the effective free space calculation captures more parts flow dynamics, especially when there exist multiple knots in the digraph model. And it runs in polynomial time once the set of circuits of the digraph is computed offline. Simulation results on selected examples are given. †This paper is an extended version of Zhang and Judd (2005) published in the Proceedings of 2005 American Control Conference, Portland, OR.