Operating Systems/Process and Thread
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[edit] Process Life Cycle
Like in real world a process too is created and destroyed. Different operating systems have different life cycles for the processes but a very general life cycle model is given below.
[edit] Dormant
A dormant stage of the process is actually a program, executable file on hard disk.
[edit] Fork
A process is said to be forked when loaded in the main memory. The execution of instructions may not start immediately. The keyword fork is basically a Unix UNIX terminology.
[edit] Ready
A process is said to be ready when it can start executing the very next moment. Many times a process may need some resource which is not available for that time. Processes which can be scheduled to run at any time by a scheduler is said to be in ready state.
[edit] Blocked
A said to be blocked when it is waiting for some interrupt to occur. Without its occurrence it can not continue. Such processes are not considered by the scheduler for scheduling.
[edit] Running
The process which is currently being executed by the processor is called the running process. In an uniprocessor system there exist only one running process at a time.
[edit] Dead
A process is said to be dead or killed when its execution is complete. Such processes are then removed from the memory of a computer. A process might end for the following reasons.
- It performed all the functions it was supposed to perform and ended normally
- It created some exception and was killed by operating system
- The parent of the process is killed.
