[OS] Process

Overview

Process state : New Ready Running Waiting Terminated
PCB (Process Control Block)

Process scheduling

Ready Queue
Job Queue
Device Queue

Long term scheduler : Job scheduler
Short term scheduler : CPU scheduler
Mid term scheduler (memory swap out int)

Context switch

Operations on processes

Inter-process communication

Information sharing
Computation speedup
Modularity
Convenience

Producer -> buffer -< Consumer
unbounded buffer / bounded buffer
circular queue

Example of IPC system

system V

int shmget : memory alloc
void* shmat : attach
int shmdt : detech
shmctl : free

POSIX

shm_open : memory alloc
shm_unlink : free
ftruncate : re-size
mmap : attach
munmap : detech

Communication in client-server systems

Socket
Pipes - Orinary Pipes / Named Pipes
RPC (Remote Procedure Call) - stub (Marshal -> Unmarshal)
RMI (Remote Method Invocation)