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1. Nisarg P atel 12202080601096 Vansh Patel 12202080601135 Zeel Goyani 12202080601 142

2. Introduction to Deadlock Deadlock is a critical system failure that occurs when two or more processes or threads are waiting for each other to release resources, leading to a complete standstill. Understanding the causes and prevention of deadlocks is essential for building robust and reliable software systems.

3. Definition of Deadlock Deadlock is a situation that can occur in concurrent systems where two or more processes are blocked, each holding a resource that is being requested by another process. This creates a circular dependency, preventing any of the processes from making progress. Deadlocks can arise when four necessary conditions are met: mutual exclusion, hold and wait, no preemption, and circular wait. Understanding these conditions is crucial for identifying and resolving deadlock scenarios in complex systems.

4. Necessary Conditions for Deadlock Mutual Exclusion: At least one resource must be non-shareable, meaning only one process can use the resource at a time. Hold and Wait: A process is holding at least one resource and is waiting to acquire additional resources held by other processes. No Preemption: Resources can only be released voluntarily by the process holding them, not taken away. Circular Wait: There is a circular chain of two or more processes, each holding one or more resources that are being requested by the next process in the chain.

5. Resource Allocation Graphs Resource Allocation Graphs (RAGs) are a powerful visual tool used to model and analyze deadlock situations in computer systems. These directed graphs depict the relationship between resources and processes, helping system administrators identify potential deadlock scenarios. In a RAG, each resource is represented as a node, and processes requesting or holding those resources are denoted by directed edges. By analyzing the structure of the graph, system administrators can detect circular wait conditions, a key characteristic of deadlocks.

6. Deadlock Detection Algorithms 1 Resource-Allocation Graph Algorithm This algorithm detects deadlocks by analyzing the resource allocation graph, which visually represents the resource requests and allocations between processes. 2 Banker's Algorithm The Banker's Algorithm determines if a system is in a safe state, where no deadlock can occur. It simulates the future resource allocation to detect potential deadlocks. 3 Wait-for Graph Algorithm This algorithm constructs a directed graph representing the "wait-for" relationships between processes, and then analyzes the graph for cycles that indicate a deadlock.

7. Deadlock Prevention Techniques Resource Allocation Careful management of resource allocation can prevent deadlocks by ensuring that resources are released in the proper order and that no processes are left waiting indefinitely for a resource. Process Termination Terminating processes that are involved in a deadlock can break the circular wait and resolve the issue. However, this approach should be used with caution to avoid unintended consequences. Circular Wait Prevention Implementing a strict resource ordering policy, where processes can only request resources in a predetermined order, can eliminate the circular wait condition and prevent deadlocks from occurring. Mutual Exclusion Avoidance Avoiding the mutual exclusion requirement for certain resources, such as using semaphores or other synchronization mechanisms, can help prevent deadlocks by eliminating the need for shared access.

8. Deadlock Avoidance Strategies 1 Resource Allocation Carefully manage resource allocation to avoid potential deadlocks. 2 Deadlock Detection Implement algorithms to detect deadlocks before they occur. 3 Deadlock Mitigation Develop strategies to break deadlocks if they do occur. Deadlock avoidance is a proactive approach to prevent deadlocks from happening in the first place. This involves carefully managing resource allocation, implementing deadlock detection algorithms, and having mitigation strategies in place to break deadlocks if they do occur. By taking a comprehensive approach, organizations can minimize the risk and impact of deadlocks in their systems.

9. Dealing with Deadlocks in Operating Systems Operating systems employ sophisticated techniques to detect and resolve deadlocks. They monitor resource allocation, maintain wait-for graphs, and implement algorithms to identify and break deadlock cycles. Proactive prevention strategies, such as resource ordering and deadlock avoidance, help avoid deadlocks altogether. When deadlocks occur, operating systems can terminate processes, preempt resources, or rollback transactions to resolve the issue. They also provide tools for system administrators to diagnose, analyze, and mitigate deadlocks in complex, real-world applications.

10. Real-World Examples of Deadlocks Airline Reservation Systems Deadlocks can occur in airline reservation systems when multiple passengers try to book the last available seat on a flight, leading to a standstill in the booking process. Database Management Deadlocks are common in database management systems when multiple transactions try to access the same set of resources in a conflicting manner, causing the system to freeze. Operating System Kernels Kernel-level deadlocks can happen when multiple processes or threads compete for system resources, leading to a standstill in the operating system's functionality.

11. REAL WORLD EXAMPLE OF DEADLOCK:

12. Conclusion and Key Takeaways 1 Importance of Understanding Deadlocks Deadlocks are critical issues in operating systems that can lead to system crashes and data loss. Understanding their root causes and mitigation strategies is essential for robust system design. 2 Prevention vs. Avoidance Deadlock prevention techniques, such as resource ordering, can eliminate the possibility of deadlocks, while avoidance strategies dynamically detect and resolve deadlocks as they occur. 3 Real-World Significance Deadlocks have been observed in many real-world systems, including database management, distributed systems, and embedded software. Vigilance and proactive mitigation are required to address this challenge. 4 Continuous Learning As software systems become more complex, the study of deadlocks remains an active area of research. Staying up-to-date with the latest advancements in deadlock detection and resolution is crucial for software engineers.

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