Write A Multi-Threaded Program Using Pthreads CMPSC 473 ✓ Solved

write a multi-threaded program using pthreads CMPSC 473, FALL 2017

Develop a multithreaded program using pthreads to simulate the scenario described, where the ship's captain John Green must manage synchronization with three merchants and the Empress of China based on their arrival times. The program should accept four inputs indicating the arrival days (1 to 10) for The Empress and each merchant. The main thread will create four threads representing each entity, wait for their completion, and then output detailed events and the decisions made through synchronization. Use mutexes and condition variables to ensure thread safety and deadlock freedom. The output must clearly convey the scheduling and decision process to facilitate TA evaluation. The program should be implemented in C, include all source files and a Makefile, and be documented with a report containing pseudo-code and sample outputs. Ensure to include both team members' names on all submissions and manage code via a private GitHub repository. The solution must be original, well-structured, and adhere to best practices in concurrent programming.

Sample Paper For Above instruction

In the context of concurrent programming, synchronization mechanisms such as mutexes and condition variables are essential to orchestrate multiple threads access to shared resources without conflicts, deadlocks, or data inconsistencies. The described problem simulates a historical voyage where a captain waits for merchants and navigates uncertainties based on their arrival times, which can be modeled effectively using pthreads in C to ensure proper thread coordination and safety.

Introduction

The scenario involves a captain, the Empress, and three merchants, each represented by individual threads in a program. The core challenge lies in coordinating their activities based on their arrival times, which are input parameters. Synchronization primitives like mutexes and condition variables enable threads to communicate about the state of arrivals and make collective decisions, reflecting the real-world scenario of waiting or proceeding based on merchant activity. This simulation can serve as a pedagogical example demonstrating key concepts in concurrent programming, including thread creation, synchronization, deadlock avoidance, and safe termination.

Design and Implementation

The solution requires several components: input parsing, thread initialization, synchronization primitive setup, and controlled thread execution, followed by output reporting. The main thread handles input reading and thread creation, while each entity thread simulates the arrival event at its predetermined time. To coordinate arrivals and decisions, the program uses mutex locks to protect shared state variables that track who has arrived, and condition variables to signal waiting threads once the relevant events occur.

The four threads include:

• The Empress thread: waits until her arrival time, then signals status.
• The merchant threads: wait for their respective arrival times, then signal their presence.
• The main thread: waits for the merchants' status, then determines whether to proceed or return.

Synchronization Logic

The synchronization involves shared flags indicating if each merchant has arrived. Mutually exclusive access to these flags is secured via mutex locks. Condition variables allow threads to wait efficiently until the arrival event occurs, minimizing CPU usage. For example, merchants wait until their scheduled arrival time, then signal their arrival. The captain, upon receiving signals from all merchants, proceeds; otherwise, if any merchant has already left, he aborts and returns.

Sample Output and Analysis

The program outputs a sequence of events detailing each thread's wait and arrival, the state changes, and the final decision. For instance, it reports when the Empress arrives, each merchant's arrival, whether the captain waits or turns back, and the reasoning based on the arrival data. Such detailed logs help TA verify correctness and facilitate debugging.

Conclusion

This implementation exemplifies how pthreads enable safe, synchronized operations among threads representing real-world entities. Proper use of mutexes and condition variables ensures correct sequencing, avoids deadlocks, and models the scenario accurately. Such simulations deepen understanding of thread communication, synchronization, and concurrent programming best practices.

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