Operating Systems - Unit 2

2.1: Processes and Process State

• 1. Definition:

  • A Process is a program that is currently in execution. It is more than just the program code; it includes the program’s current activity, represented by its memory, open files, and the value of its program counter.

• 2. Process in Memory:

  • When a program is run, the OS allocates memory for its different parts:
    • Text Section: The compiled code.
    • Data Section: Global variables.
    • Heap: Memory that is dynamically allocated during runtime.
    • Stack: Memory for local variables and function calls.

• 3. Process States:

  • As a process executes, it moves through different states. A simplified model includes:
    • New: The process is being created.
    • Ready: The process is waiting to be assigned to a CPU to run. It has everything it needs except the CPU itself.
    • Running: Instructions are being executed by the CPU.
    • Waiting: The process is waiting for some event to occur (e.g., waiting for an I/O operation like reading a file from the disk to complete).
    • Terminated: The process has finished execution.

• 4. Connection to Practice (AutoCleanSE):

  • When we ran the command python autocleanse.py, the Fedora OS performed the following actions:
    1. It created a New process.
    2. It loaded the Python interpreter and our script into memory.
    3. The process moved to the Ready state.
    4. The OS scheduler assigned it to a CPU, moving it to the Running state.
    5. When our script called pd.read_csv(), it likely moved to the Waiting state until the file was fully read from the disk.
    6. Once finished, it moved to the Terminated state.

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