Linuxオペレーティングシステムマルチスレッド同期反発Mutexの使用

int pthread_mutex_unlock(pthread_mutex_t *mutex); 

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

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;// 
int lock_var;// 
time_t end_time;

void pthread1(void *arg);// 1
void pthread2(void *arg);// 2

int main(int argc, char *argv[])
{
	pthread_t id1,id2;
	pthread_t mon_th_id;
	int ret;

	end_time = time(NULL)+10;
	pthread_mutex_init(&mutex,NULL);// mutex ， （ NULL）
	ret=pthread_create(&id1,NULL,(void *)pthread1, NULL);// 1
	if(ret!=0)
		perror("pthread cread1");

	ret=pthread_create(&id2,NULL,(void *)pthread2, NULL);// 2
	if(ret!=0)
		perror("pthread cread2");

	pthread_join(id1,NULL);// 1 
	pthread_join(id2,NULL);// 2 

	exit(0);
}

void pthread1(void *arg)
{
	int i;
	while(time(NULL) < end_time)
	{
		if(pthread_mutex_lock(&mutex)!=0) // 
		{
			perror("pthread_mutex_lock");
		}else{
			printf("pthread1:pthread1 lock the variable
");
		}
			
		for(i=0;i<2;i++)
		{
			sleep(2);
			lock_var++;
		}
		
		if(pthread_mutex_unlock(&mutex)!=0) // 
		{
			perror("pthread_mutex_unlock");
		}else{
			printf("pthread1:pthread1 unlock the variable
");
		}
			
		sleep(1);
	}
}

void pthread2(void *arg)
{
	int nolock=0;
	int ret;
	while(time(NULL) < end_time){
		ret=pthread_mutex_trylock(&mutex);// 
		if(ret==EBUSY){
			printf("pthread2:the variable is locked by pthread1
");
		}else{
			if(ret!=0){
				perror("pthread_mutex_trylock");
				exit(1);
			}else{
				printf("pthread2:pthread2 got lock.The variable is %d
",lock_var);
			}
			
			if(pthread_mutex_unlock(&mutex)!=0){// 
				perror("pthread_mutex_unlock");
			}else{
				printf("pthread2:pthread2 unlock the variable
");
			}
		}
		sleep(1);
	}
}

pthread2:pthread2 got lock.The variable is 0
pthread2:pthread2 unlock the variable
pthread1:pthread1 lock the variable
pthread2:the variable is locked by pthread1
pthread2:the variable is locked by pthread1
pthread2:the variable is locked by pthread1
pthread1:pthread1 unlock the variable
pthread2:pthread2 got lock.The variable is 2
pthread2:pthread2 unlock the variable
pthread1:pthread1 lock the variable
pthread2:the variable is locked by pthread1
pthread2:the variable is locked by pthread1
pthread2:the variable is locked by pthread1
pthread2:the variable is locked by pthread1
pthread1:pthread1 unlock the variable
pthread2:pthread2 got lock.The variable is 4
pthread2:pthread2 unlock the variable