/******************************************************** * An example source module to accompany... * * "Using POSIX Threads: Programming with Pthreads" *     by Brad nichols, Dick Buttlar, Jackie Farrell *     O'Reilly & Associates, Inc. * ******************************************************** * polling.c *  * Showing polling of condition versus proper condition * variable use. */#include <pthread.h> pthread_mutex_t db_lock=PTHREAD_MUTEX_INITIALIZER;pthread_cond_t  db_inited=PTHREAD_COND_INITIALIZER;int db_initialized=0;void r1(void){   pthread_mutex_lock(&db_lock);   while(!db_initialized) {      pthread_mutex_unlock(&db_lock);      sleep(1);      pthread_mutex_lock(&db_lock);   }   pthread_mutex_unlock(&db_lock);      /* go do something */}void r2(void){   pthread_mutex_lock(&db_lock);   while(!db_initialized)      pthread_cond_wait(&db_inited, &db_lock);   pthread_mutex_unlock(&db_lock);   /* go do something */}intmain(void){}