Ardika Sulistija: Created page with "Related topics: * Zombie Process * Orphan Process * Process Control Block (PCB) * Threads ---- Processes: program in execution. * Address space (memory) the program can use * State (registers, including program counter and stack pointer) * OS keeps track of all processes in a process table. * Processes can create other processes. A program i..."

2024-09-11T14:22:00Z

Created page with "Related topics: * Zombie Process * Orphan Process * Process Control Block (PCB) * Threads ---- Processes: program in execution. * Address space (memory) the program can use * State (registers, including program counter and stack pointer) * OS keeps track of all processes in a process table. * Processes can create other processes. A program i..."

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Related topics:
* [[Zombie Process|Zombie Process]]
* [[Orphan Process|Orphan Process]]
* [[Process Control Block (PCB)|Process Control Block (PCB)]]
* [[Threads|Threads]]

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Processes: program in execution.

* Address space (memory) the program can use
* State (registers, including program counter and stack pointer)
* OS keeps track of all processes in a process table.
* Processes can create other processes.

A program is a passive entity stored on a disk (executable file), the process is active.

A program becomes a process when the executable file is loaded into memory.

One program can be several processes.
* Consider multiple users executing the same program.

OS provides mechanisms for:
* process creation
* process termination
* forking of process
* prioritizing and scheduling processes

====Process Creation====
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Generally, processes are identified and managed via a process identifier (PID).

Resource sharing options:
* Parent and children share all resources
* Children share subset of parent's resources
* Parent and child share no resources

Execution options:
* Parent and children execute concurrently
* Parent waits until children terminate

====Process Termination====
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Process terminates = all children terminated.
* Cascading termination - All children, grandchildren, etc. are terminated.
* Termination initiated by OS.

May wait for termination of child by using the wait() system call. Call returns status information and the pid of the terminated process
pid = wait(&status);

Zombie process: if no parent waiting (did not invoke wait()), then the process is a zombie.

Orphan process: if parent is terminated without invoking wait(), process is an orphan.

Processes - Revision history