On the conditional variables of pthread

This issue studies the conditional variables of pthreads. Find a study note from the Internet, see "Cnblogs-blueclue's tech Blog-posix line libraries condition variables using--pthreads line Libraries Instance Note 4".

Test the code on Windows, make a few changes, and paste the following:

There are a couple of points to note:

1. The delay function is sleep (), in the header file <windows.h>. The function is used to delay the execution of a thread;

2. The polling times are set to the condition of the while loop, and the polling times should be consistent in the signal sending and receiving functions;

#include  <pthread.h> #include  <stdlib.h> #include  <stdio.h> #include  < Windows.h>int count = 0;pthread_cond_t count_threshold_cv;pthread_mutex_t count_ Mutex;void * watch_count (void *t) {    long my_id =  (Long)  t;    while (count < 15) {         pthread_mutex_lock (&count_mutex);         printf ("Starting  watch_count ():  thread %ld\n ",  my_id);         printf ("Watch_count ():  thread %ld going into wait ...\n",  my_id);         pthread_cond_wait (&count_threshold_cv, &count_mutex);         /*suspend execution for an interval  Of time*/   &nbsP;    //sleep (100000);         printf ("Watch_count ( ):  thread %ld condition signal received.\n ",  my_id);         printf ("Watch_count ():  thread %ld count now = %d.\n",  my_id, count);         pthread_mutex_unlock (&count_mutex );     }    pthread_exit (NULL);} Void * inc_count (void *t) {    long my_id =  (long)  t;     while (count < 15) {        pthread _mutex_lock (&count_mutex);        count++;         if (count > 10) {             printf ("Inc_count (): &NBSP;THREAD&NBSP;%LD,&NBSp;count = %d threshold reached ",  my_id, count);             pthread_cond_signal (&AMP;COUNT_THRESHOLD_CV);             printf ("just sent signal.\n");         }        printf ("Inc_count ():  thread %ld, count = %d, unlocking mutex\n ",  my_id, count);         pthread_mutex_unlock (&count_mutex);     }     pthread_exit (NULL);} Int main () {    pthread_t threads[3];    pthread_mutex_init ( &count_mutex, null);     pthread_cond_init (&count_threshold_cv, null);     long t1 = 1, t2 = 2, t3 = 3;&nbSp;   pthread_create (&threads[0], NULL, watch_count,  (void *)  t1);     pthread_create (&threads[1], NULL, inc_count,  (void *)  t2) ;     pthread_create (&threads[2], NULL, inc_count,  (void *)  t3 );     for (int i = 0; i < 3; i++) {         pthread_join (threads[i], null);    }     pthread_mutex_destroy (&count_mutex);     pthread_cond_destroy (&count_ THRESHOLD_CV);     pthread_exit (NULL);     return 0;}

This article from "Hu A Knife" blog, declined reprint!

On the conditional variables of pthread