线程的执行的无序性－－－生产消费者

源程序：

#include <stdio.h>

#include <string.h>

#include <pthread.h>

#include <errno.h>

#include <semaphore.h>

#define BUFSIZE 4

#define NUMBER 8

int sum_of_number=0;

sem_t write_res_number;

sem_t read_res_number;

struct recycle_buffer

{

int buffer[BUFSIZE];

int head,tail;

}re_buf;

pthread_mutex_t buffer_mutex=PTHREAD_MUTEX_INITIALIZER;

void *prod(void *arg)

{

int i;

for(i=0;i<=8;i++)

{

sem_wait(&write_res_number);

pthread_mutex_lock(&buffer_mutex);

re_buf.buffer[re_buf.tail]=i;

re_buf.tail=(re_buf.tail+1)%BUFSIZE;

printf("procuder %d write %d./n",(int)pthread_self(),i);

pthread_mutex_unlock(&buffer_mutex);

sem_post(&read_res_number);

}

return NULL;

}

void *consumer(void *arg)

{

int i,num;

for(i=0;i<=8;i++)

{

sem_wait(&read_res_number);

pthread_mutex_lock(&buffer_mutex);

num=re_buf.buffer[re_buf.head];

re_buf.head=(re_buf.head+1)%BUFSIZE;

printf("consumer %d read %d./n",(int)pthread_self(),num);

pthread_mutex_unlock(&buffer_mutex);

sum_of_number+=num;

sem_post(&write_res_number);

}

return NULL;

}

int main()

{

pthread_t pid,cid;

int i;

re_buf.head=0;

re_buf.tail=0;

for(i=0;i<BUFSIZE;i++)

re_buf.buffer[i]=0;

sem_init(&write_res_number,0,BUFSIZE);

sem_init(&read_res_number,0,0);

pthread_create(&pid,NULL,prod,NULL);

pthread_create(&cid,NULL,consumer,NULL);

pthread_join(pid,NULL);

pthread_join(cid,NULL);

printf("the sum of number is %d/n",sum_of_number);

for(i=0;i<4;i++)

printf("%d/n",re_buf.buffer[i]);

return 0;



}

运行结果：

1。

procuder -1210569840 write 0.

procuder -1210569840 write 1.

consumer -1218962544 read 0.

procuder -1210569840 write 2.

consumer -1218962544 read 1.

consumer -1218962544 read 2.

procuder -1210569840 write 3.

procuder -1210569840 write 4.

procuder -1210569840 write 5.

procuder -1210569840 write 6.

consumer -1218962544 read 3.

consumer -1218962544 read 4.

consumer -1218962544 read 5.

consumer -1218962544 read 6.

procuder -1210569840 write 7.

procuder -1210569840 write 8.

consumer -1218962544 read 7.

consumer -1218962544 read 8.

the sum of number is 36

8

5

6

7

2。

procuder -1209984112
write 0.

procuder -1209984112 write 1.

procuder -1209984112 write 2.

procuder -1209984112 write 3.

consumer -1218376816 read 0.

consumer -1218376816 read 1.

consumer -1218376816 read 2.

consumer -1218376816 read 3.

procuder -1209984112 write 4.

procuder -1209984112 write 5.

procuder -1209984112 write 6.

procuder -1209984112 write 7.

consumer -1218376816 read 4.

consumer -1218376816 read 5.

consumer -1218376816 read 6.

consumer -1218376816 read 7.

procuder -1209984112 write 8.

consumer -1218376816 read 8.

the sum of number is 36

8

5

6

7