What is' Process? Draw the state transition diagram of a process state.
What is a Process? State Transition Diagram in Operating Systems
A process in an operating system is a program in execution. It includes the program code, current activity (values of CPU registers, program counter), memory (code, data, stack, heap), and resources like open files and I/O. The OS manages processes to share CPU and other resources efficiently.
Common Process States
- New: The process is being created.
- Ready: The process is loaded in memory and waiting for CPU.
- Running: The process is currently executing on the CPU.
- Blocked (Waiting): The process is waiting for an I/O or an event to occur.
- Terminated: The process has finished execution.
Process State Transition Diagram (ASCII)
+-----+ admit +-------+ dispatch +--------+
| New | ---------------> | Ready | -----------> | Running|
+-----+ +---+---+ +---+----+
^ ^ |
| | | time slice/interrupt
I/O done | +---------------------+
| |
+---+---+ |
|Blocked| <---- I/O wait ---+
+-------+
exit
|
v
+-----------+
|Terminated|
+-----------+
Key Transitions
- New → Ready (admit): The OS admits the process into the ready queue.
- Ready → Running (dispatch): The CPU scheduler selects the process to run.
- Running → Ready (interrupt/time slice): Preemption when time quantum expires or a higher-priority process arrives.
- Running → Blocked (I/O or event wait): Process waits for I/O or an external event.
- Blocked → Ready (I/O or event done): Required I/O or event completes; process becomes ready again.
- Running → Terminated (exit): Process finishes or is aborted.
This model helps visualize how the OS schedules CPU time and handles I/O, ensuring fair and efficient process management.