Algorithm: FIFO (First In, First Out) Ticket AlgorithmObjective:To ensure that processes (or threads) access a shared resource in the exact order they requested it — maintaining fairness and avoiding starvation.<h5>1. Concept Overview</h5>The FIFO Ticket Algorithm is a synchronization mechanism used in concurrent systems.Each process gets a ticket number when it requests access to a critical section.Processes are served in increasing order of their ticket numbers — just like people waiting in line for tickets.<h5>2. Data Structures</h5><ul><li>ticket: A shared integer counter that gives out unique ticket numbers.</li><li>turn: A shared integer indicating the ticket number currently being served.</li><li>my_ticket[i]: The ticket number assigned to process i.</li></ul><h5>3. Initialization</h5>ticket = 0turn = 0for each process i: my_ticket[i] = -1<h5>4. Algorithm Steps</h5>Step 1: Request Entry (Entering Critical Section)1. my_ticket[i] = FetchAndIncrement(ticket) // Atomically assign a unique ticket number to process i 2. while (my_ticket[i] != turn): wait() // Busy wait or block until it's this process's turnStep 2: Execute Critical Section3. Perform critical section operationsStep 3: Exit Critical Section4. turn = turn + 1 // Allow the next ticket holder to enter<h5>5. Practical Example</h5>Scenario:Three customers (P1, P2, P3) want to buy tickets at a counter.Result:All customers are served in the exact order they arrived — no starvation, no priority inversion.<h5>6. Key Properties</h5><ul><li>Fairness: Guaranteed — first requester is first served.</li><li>Mutual Exclusion: Only one process in the critical section at a time.</li><li>Bounded Waiting: Each process waits a finite time.</li><li>Simplicity: Easy to implement using atomic operations.</li></ul><h5>7. Practical Implementation Note</h5>In real systems, the FetchAndIncrement() operation is implemented using atomic CPU instructions (like atomic_fetch_add() in C/C++).For distributed systems, ticket counters can be managed using centralized servers or distributed consensus mechanisms.End of Algorithm

Algorithm: FIFO First In, First Out Ticket Algorithm

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