源代码：

#include <stdio.h>

#include <pthread.h>

#include <sched.h>





void *producter_f (void *arg);

void *consumer_f (void *arg);









int buffer_has_item=0;

pthread_mutex_t mutex;





int running =1 ;





int main (void)

{

pthread_t consumer_t;

pthread_t producter_t;



pthread_mutex_init (&mutex,NULL);



pthread_create(&producter_t, NULL,(void*)producter_f, NULL );

pthread_create(&consumer_t, NULL, (void *)consumer_f, NULL);

usleep(1);

running =0;

pthread_join(consumer_t,NULL);

pthread_join(producter_t,NULL);

pthread_mutex_destroy(&mutex);



return 0;

}





void *producter_f (void *arg)

{

while(running)

{

pthread_mutex_lock (&mutex);

buffer_has_item++;

printf("生产，总数量:%d\n",buffer_has_item);

pthread_mutex_unlock(&mutex);

}

}





void *consumer_f(void *arg)

{

while(running)

{

pthread_mutex_lock(&mutex);

buffer_has_item--;


printf("消费，总数量:%d\n",buffer_has_item);

pthread_mutex_unlock(&mutex);

}

}

错误场景：

[root@luozhonghua 04]# gcc -o mutex ex04-5-mutex.c

/tmp/ccZuFiqr.o: In function `main':

ex04-5-mutex.c:(.text+0x3d): undefined reference to `pthread_create'

ex04-5-mutex.c:(.text+0x61): undefined reference to `pthread_create'

ex04-5-mutex.c:(.text+0x8b): undefined reference to `pthread_join'

ex04-5-mutex.c:(.text+0x9f): undefined reference to `pthread_join'

collect2: ld returned 1 exit status

分析：pthread 库不是 Linux 系统默认的库，连接时须要使用静态库 libpthread.a

处理：

在编译中加 -lpthread 參数

[root@luozhonghua 04]# gcc -lpthread -o mutex ex04-5-mutex.c