Multi-Programming System with Priority-Based Dispatcher

Overview

This project simulates a multi-programming system with a four-level priority dispatcher implemented in Java. The dispatcher operates under constraints of limited resources, managing multiple processes and dynamically prioritizing them based on a variety of factors. This system leverages several scheduling algorithms, resource allocation checks, and timeouts to maintain efficient process management. The required JAR file for the project is located in the dist folder.

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Key Concepts

• Dispatcher: Manages the allocation of CPU time and resources to processes based on priority and availability.
• Scheduling Algorithms:
  • FCFS (First-Come-First-Serve)
  • Round Robin with Quantum (1-second time slice)
  • Feedback Mechanism
• Process Attributes: Each process includes arrival time, priority level, processing time, and other properties. Processes also request specific hardware resources.

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Project Details

1. Sorting and Queuing of Incoming Processes

• Process Initialization: Processes are read from an input file and instantiated as objects with assigned attributes.
• Queue Assignment: Incoming processes are placed into four priority queues according to their priority levels.
• Sorting: Processes are sorted based on ArrivalTime to avoid repeated searches. The sorting algorithm uses the Selection Short method based on ArrivalTime.

2. Dispatcher Operation

• Zero Priority Handling: The dispatcher starts with zero-priority processes. If all requested resources are available, the process executes following the FCFS algorithm within memory constraints (64 MB for real-time, 960 MB for others).
• Resource Management: Resources are allocated and released via get_Resource() and release_Resource() functions.
• Feedback Mechanism: Non-zero priority processes execute for one second, then have their priority reduced and are suspended. Suspended processes wait in a separate queue.
• Timeout Handling: timeOutCheck removes processes exceeding a 20-second wait, releasing resources and logging a timeout message.

3. Improvements and Considerations

• Sorting Efficiency: The sorting algorithm could be optimized for better performance.
• Level Adaptation: The dispatcher currently supports four levels; higher levels would require additional code.
• Resource Management: Automating the get_Resource() and release_Resource() functions could simplify resource handling.

4. Process Class

• Process Object Creation: Each process read from the input file is instantiated from a custom Process class.
• Execution: The execute function of each process object runs a JAR file via Runtime.exec(), displaying process information on the console.
• Colored Output: Using the ColoredSystemOutPrintLn class, ANSI escape codes are applied to process messages, displaying them in different colors.

5. Dispatcher Comparison

• Dispatcher Role: Manages CPU usage, places processes, and adjusts user mode as needed.
• CPU Access Control: Processes access the CPU based on priority and available resources.
• Priority Handling: Higher priority processes can suspend lower priority ones. Processes exceeding a 20-second wait are timed out.

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Required JAR File

The JAR file for this project can be found in the dist directory.