code14_1.cpp

#include <pthread.h>
#include <unistd.h>
#include <stdio.h>

int a = 0;
int b = 0;
pthread_mutex_t mutex_a;
pthread_mutex_t mutex_b;

void * another(void *arg)
{
	pthread_mutex_lock(&mutex_b);
	printf("in child thread,got mutex b, waiting for mutex a\n");
	sleep(5);
	++b;
	pthread_mutex_lock(&mutex_a);
	b += a++;
	pthread_mutex_unlock(&mutex_a);
	pthread_mutex_unlock(&mutex_b);
	pthread_exit(NULL);
}

int main()
{
	pthread_t id;

	pthread_mutex_init(&mutex_a,NULL);
	pthread_mutex_init(&mutex_b,NULL);
	pthread_create(&id,NULL,another,NULL);

	pthread_mutex_lock(&mutex_a);
	printf("in parent thread, got mutex a,waiting for mutex b\n");
	sleep(5);
	++a;
	pthread_mutex_lock(&mutex_b);
	a += b++;
	pthread_mutex_unlock(&mutex_b);
	pthread_mutex_unlock(&mutex_a);
	pthread_join(id,NULL);
	pthread_mutex_destroy(&mutex_a);
	pthread_mutex_destroy(&mutex_b);
	return 0;
}