Skip to content

Latest commit

 

History

History
70 lines (45 loc) · 1.99 KB

README.md

File metadata and controls

70 lines (45 loc) · 1.99 KB

UNIX-POSIX

C programs that rely on POSIX standards

Signals and interrupts

  • Signals are a limited form of inter-process communication (IPC)

  • Used in Unix, Unix-like, and other POSIX-compliant operating systems

  • Signal is an asynchronous notification sent to a process or to a specific thread within the same process in order to notify it of an event that occurred

  • When a signal is sent, the operating system interrupts the target process' normal flow of execution to deliver the signal

    • If the process has previously registered a signal handler, that routine is executed
    • Otherwise, the default signal handler is executed
#include <signal.h>

int sighold(int sig);
int sigignore(int sig);
int sigpause(int sig);
int sigrelse(int sig);
void (*sigset(int sig, void (*disp)(int)))(int);

Examples

  1. Prime numbers

    • SIGALRM, SIGINT
    • Pause program and periodically print status

  2. Signal handler

    • SIGUSR1, SIGUSR2
    • Handle and keep track of multiple signals with different priority

  3. Signal generator

    • Generate signals for handler

Multiprocessing and multithreading

  • A thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, part of the operating system

  • A thread is a component of a process

  • Multiple threads can exist within one process, executing concurrently and sharing resources such as memory, while different processes do not share these resources

  • The threads of a process share its executable code and the values of its dynamically allocated variables and non-thread-local global variables at any given time

Take a loook at: https://computing.llnl.gov/tutorials/pthreads/

Examples

Threads

Processes

Synchronization

  1. Lamport and Dekker algorithms
  2. Atomic operations (TAS)
  3. Semaphores
  4. Mutex
  5. Monitor