NEU操作系统实验课4——线程同步

Posted 2020-09-08 徐王

实验要求：

创建两个线程按数字顺序打印10以下自然数，其中一个线程打印1-3及8-10；另一个线程打印4-6。要求使用线程同步机制实现上述打印顺序。

看网上的资料学习了两种写法

C++11的，使用了std::thread

 1 #include <unistd.h>
 2 #include <thread>
 3 #include <iostream>
 4 #include <mutex>
 5 #include<bits/stdc++.h>
 6 void Fun_1();
 7 void Fun_2();
 8 unsigned int counter=0;
 9 std::mutex mtx;
10 
11 int main()
12 {
13     std::thread thrd_1(Fun_1);
14     std::thread thrd_2(Fun_2);
15     thrd_1.join();
16     thrd_2.join();
17     //system("pause");
18     return 0;
19 }
20 
21 void Fun_1()
22 {
23     while(counter<10){
24         if(counter<3||counter>5)continue;
25         std::lock_guard<std::mutex> mtx_locker(mtx);
26         ++counter;
27         std::cout << "Function 1 counting " << counter << "...\n";
28         usleep(1);
29     }
30 }
31 
32 void Fun_2()
33 {
34     while(counter<10){
35         if(counter>2&&counter<6)continue;
36         std::lock_guard<std::mutex> mtx_locker(mtx); 
37         ++counter;
38         std::cout << "Function 2 counting " << counter << "...\n";
39         usleep(1);
40     }
41 }

C++11

C语言的，使用pthread

 1 #include <stdio.h>
 2 #include <pthread.h>
 3 #include <stdlib.h>
 4 #include <unistd.h>
 5 
 6 pthread_mutex_t mutex;
 7 pthread_cond_t cond1;
 8 pthread_cond_t cond2;
 9 int cnt=0;
10 
11 
12 void hander(void *arg)
13 { 
14     free(arg);
15     (void)pthread_mutex_unlock(&mutex);
16 }
17 
18 void *thread1(void *arg)
19 {
20     pthread_cleanup_push(hander,&mutex);
21     printf("thread1\n1\n2\n3\n");
22     pthread_mutex_lock(&mutex);
23     pthread_cond_wait(&cond1,&mutex);
24     pthread_mutex_unlock(&mutex);
25     printf("thread1\n7\n8\n9\n10\n");
26     pthread_cleanup_pop(0);
27 }
28 
29 void *thread2(void *arg)
30 {
31     pthread_mutex_lock(&mutex);
32     pthread_cond_wait(&cond2,&mutex);
33     printf("thread2\n4\n5\n6\n");
34     pthread_cond_signal(&cond1);
35     pthread_mutex_unlock(&mutex);
36 }
37 
38 int main()
39 {
40     pthread_t tid1,tid2;
41     pthread_mutex_init(&mutex,NULL);
42     pthread_cond_init(&cond1,NULL);
43     pthread_cond_init(&cond2,NULL);
44     pthread_create(&tid1,NULL,thread1,NULL);
45     pthread_create(&tid2,NULL,thread2,NULL);
46     
47     sleep(1);
48     pthread_cond_signal(&cond2);
49     //sleep(2);
50     pthread_exit(0);
51     return 0;
52 }

C