Imprime 1 2 3 infinitamente usando hilo. Cree tres subprocesos, a saber, T1, T2 y T3, de modo que impriman una secuencia 1 2 3 infinitamente.
Ejemplos:
Output :1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 ......
Requisito previo: subprocesos en C
Acercarse :
- Inicie un bucle infinito e inicialice una variable ‘hecho’ en 1.
- Ahora, verifique que el valor de hecho no sea igual a 1.
- Si se trata de bloqueo de condición de espera en espera, de lo contrario, imprima n y, respectivamente, señale el siguiente n consecutivo.
// C code to print 1 2 3 infinitely using pthread
#include <stdio.h>
#include <pthread.h>
// Declaration of thread condition variables
pthread_cond_t cond1 =
PTHREAD_COND_INITIALIZER;
pthread_cond_t cond2 =
PTHREAD_COND_INITIALIZER;
pthread_cond_t cond3 =
PTHREAD_COND_INITIALIZER;
// mutex which we are going to
// use avoid race condition.
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
// done is a global variable which decides
// which waiting thread should be scheduled
int done = 1;
// Thread function
void *foo(void *n)
{
while(1) {
// acquire a lock
pthread_mutex_lock(&lock);
if (done != (int)*(int*)n) {
// value of done and n is not equal,
// hold wait lock on condition variable
if ((int)*(int*)n == 1) {
pthread_cond_wait(&cond1, &lock);
} else if ((int)*(int*)n == 2) {
pthread_cond_wait(&cond2, &lock);
}
else {
pthread_cond_wait(&cond3, &lock);
}
}
// done is equal to n, then print n
printf("%d ", *(int*)n);
// Now time to schedule next thread accordingly
// using pthread_cond_signal()
if (done == 3) {
done = 1;
pthread_cond_signal(&cond1);
}
else if(done == 1) {
done = 2;
pthread_cond_signal(&cond2);
} else if (done == 2) {
done = 3;
pthread_cond_signal(&cond3);
}
// Finally release mutex
pthread_mutex_unlock(&lock);
}
return NULL;
}
// Driver code
int main()
{
pthread_t tid1, tid2, tid3;
int n1 = 1, n2 = 2, n3 = 3;
// Create 3 threads
pthread_create(&tid1, NULL, foo, (void *)&n1);
pthread_create(&tid2, NULL, foo, (void *)&n2);
pthread_create(&tid3, NULL, foo, (void *)&n3);
// infinite loop to avoid exit of a program/process
while(1);
return 0;
}
Producción :
1 2 3 1 2 3 1 2 3 1 2 3 ...