码海拾遗：Linux多线程mutex锁

　　多线程计数，每个线程累加10个数。

　　实现：

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

 pthread_mutex_t num_lock;

 int num = ;
 int sum = ;

 void* foo1()
 {
 #if 1
     pthread_mutex_lock(&num_lock);
     for(int i = ;i<;++i)
     {
         num += ;
         sum += num;
         printf("thread 1,num = %d,sum = %d\n",num,sum);
         usleep();
     }
     pthread_mutex_unlock(&num_lock);
 #else
     for(int i = ;i<;++i)
     {
         num += ;
         sum += num;
         printf("thread 1,num = %d,sum = %d\n",num,sum);
         usleep();
     }
 #endif
     return NULL;
 }

 void* foo2()
 {
 #if 1
     pthread_mutex_lock(&num_lock);
     for(int i = ;i<;++i)
     {
         num += ;
         sum += num;
         printf("thread 2,num = %d,sum = %d\n",num,sum);
         usleep();
     }
     pthread_mutex_unlock(&num_lock);
 #else
     for(int i = ;i<;++i)
     {
         num += ;
         sum += num;
         printf("thread 2,num = %d,sum = %d\n",num,sum);
         usleep();
     }
 #endif
     return NULL;
 }

 int main(int argc,char* argv[])
 {
     pthread_t tid1,tid2;
     int err;

     pthread_mutex_init(&num_lock,NULL);

     err = pthread_create(&tid1,NULL,foo1,NULL);
     if(err != )
     {
         printf("error code:%d,reason:%s\n",err,strerror(err));
         return -;
     }

     err = pthread_create(&tid2,NULL,foo2,NULL);
     if(err != )
     {
         printf("error code:%d,reason:%s\n",err,strerror(err));
         return -;
     }

     //for(int i = 0;i<10;++i)
     //    printf("main thread, num = %d\n",num++);

     err = pthread_join(tid1,NULL);
     if(err != )
     {
         printf("error code:%d,reason:%s\n",err,strerror(err));
         return -;
     }
     err = pthread_join(tid2,NULL);
     if(err != )
     {
         printf("error code:%d,reason:%s\n",err,strerror(err));
         return -;
     }

     pthread_mutex_destroy(&num_lock);

     return ;
 }