喜羊羊系列之【 线程 】互斥锁+信号量

 1. 编写一个基本的多线程程序（主线程里面创建一个子线程）

/*************************************************************************
	> File Name: 1_homework.c
	> Author: 梁惠涌
	> Addr: 
	> Created Time: 2015年04月22日 星期三 15时22分34秒
 ************************************************************************/

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<pthread.h>    
#include <semaphore.h> //sem_t 的声明

void *fun1(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        *((int *)arg) += 2;
        printf("fun1 the num is: %d \n",*((int*)arg));
        sleep(1);
    }    
    pthread_exit(0);      //主线程结束
}

int main(){
    int num=3, ret1;
    pthread_t thread1;

    ret1 = pthread_create(&thread1, NULL, fun1, (void *)&num);
    if(ret1 != 0){
        perror("pthread_create1");
        exit(0);
    }
    sleep(1);
    printf("=================== main end ================\n");
    pthread_exit(0);      //主线程结束
}

 2. 把上面的程序改为子线程给父线程传递返回值

/*************************************************************************
	> File Name: 2_homework.c
	> Author: 梁惠涌
	> Addr:
	> Created Time: 2015年04月22日 星期三 15时39分49秒
 ************************************************************************/

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

void *fun1(void *arg){
    int num=100;
    printf("---------------pthread--------------\n");
    printf("the num is: %d \n", num);
    printf("---------------  end  --------------\n");
    pthread_exit((void *)num);      //主线程结束
}

int main(){
    int  ret1, num;
    pthread_t thread1;

    ret1 = pthread_create(&thread1, NULL, fun1, NULL);
    if(ret1 != 0){
        perror("pthread_create1");
        exit(0);
    }
    pthread_join(thread1,(void *)&num);
    printf("---------------  main  --------------\n");
    printf("return the num is: %d \n", (int )num);
    printf("---------------   end  --------------\n");
    
    pthread_exit(0);      //主线程结束
}

 3. 用多线程写一个程序，实现对数据的读写（可以是一个全局变量或其他的数据）

/*************************************************************************
	> File Name: 3_homework.c
	> Author: 梁惠涌
	> Addr: 
	> Created Time: 2015年04月22日 星期三 15时53分00秒
 ************************************************************************/

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<pthread.h>    
#include <semaphore.h> //sem_t 的声明

void *fun1(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        *((int *)arg) += 2;
        printf("the num write: %d \n",*((int*)arg));
        sleep(1);
    }    
    pthread_exit(0);      //主线程结束
}

void *fun2(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        printf("the num read is: %d \n",*((int*)arg));
        sleep(1);
    }    
    pthread_exit(0);      //主线程结束
}
int main(){
    int num=0, ret1;
    pthread_t thread1, thread2;

    ret1 = pthread_create(&thread1, NULL, fun1, (void *)&num);
    if(ret1 != 0){
        perror("pthread_create1");
        exit(0);
    }

    ret1 = pthread_create(&thread2, NULL, fun2, (void *)&num);
    if(ret1 != 0){
        perror("pthread_create2");
        exit(0);
    }
    
    sleep(1);
    printf("=================== main end ================\n");
    pthread_exit(0);      //主线程结束
}

 4. 分别用信号量和互斥锁实现第3个作业的读写互斥

/*************************************************************************
	> File Name: 4_homework.c
	> Author: 梁惠涌
	> Addr:
	> Created Time: 2015年04月22日 星期三 15时57分54秒
 ************************************************************************/

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<pthread.h>    
#include <semaphore.h> //sem_t 的声明

sem_t sem;     //信号量声明
pthread_mutex_t mutex;  //互斥锁声明

void *fun1(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        sem_wait(&sem);
        *((int *)arg) += 2;
        printf("==信号量== num write: %d \n",*((int*)arg));
        sleep(1);
        sem_post(&sem);
    }    
    pthread_exit(0);      //主线程结束
}

void *fun2(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        sem_wait(&sem);
        printf("==信号量== num read is: %d \n",*((int*)arg));
        sleep(1);
        sem_post(&sem);
    }    
    pthread_exit(0);      //主线程结束
}

void *fun3(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        pthread_mutex_lock(&mutex);
        *((int *)arg) += 2;
        printf(">>互斥锁>> num write: %d \n",*((int*)arg));
        sleep(1);
        pthread_mutex_unlock(&mutex);
    }    
    pthread_exit(0);      //主线程结束
}

void *fun4(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        pthread_mutex_lock(&mutex);
        printf(">>互斥锁>> num read is: %d \n",*((int*)arg));
        sleep(1);
        pthread_mutex_unlock(&mutex);
    }    
    pthread_exit(0);      //主线程结束
}

int main(){
    //------------------------信号量互斥--------------------
    int num1=0, ret1;
    pthread_t thread1, thread2;

    sem_init(&sem, 0, 1);
    ret1 = pthread_create(&thread1, NULL, fun1, (void *)&num1);
    if(ret1 != 0){
        perror("pthread_create1");
        exit(0);
    }
    ret1 = pthread_create(&thread2, NULL, fun2, (void *)&num1);
    if(ret1 != 0){
        perror("pthread_create2");
        exit(0);
    }
    

    //------------------------互斥锁互斥--------------------
    int num2=1000, ret2;
    pthread_t thread_1, thread_2;
    pthread_mutex_init(&mutex, NULL);

    ret2 = pthread_create(&thread_1, NULL, fun3, (void *)&num2);
    if(ret2!= 0){
        perror("pthread_create1");
        exit(0);
    }
    ret1 = pthread_create(&thread_2, NULL, fun4, (void *)&num2);
    if(ret2 != 0){
        perror("pthread_create2");
        exit(0);
    }
   
    printf("=================== main end ================\n");
    pthread_exit(0);      //主线程结束
}

 5. 用信号量实现第3个作业的读写同步

/*************************************************************************
	> File Name: 5_homework.c
	> Author: 梁惠涌
	> Addr: 
	> Created Time: 2015年04月22日 星期三 16时36分01秒
 ************************************************************************/
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<pthread.h>    
#include <semaphore.h> //sem_t 的声明

sem_t w_sem, r_sem;     //信号量声明

void *fun1(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        sem_wait(&w_sem);
        *((int *)arg) += 2;
        printf(">>>> num write: %d \n",*((int*)arg));
        sleep(1);
        sem_post(&r_sem);
    }    
    pthread_exit(0);      //主线程结束
}

void *fun2(void *arg){
    pthread_detach( pthread_self() );           //与主线程分离
    while(1){
        sem_wait(&r_sem);
        printf(">>>> num read is: %d \n",*((int*)arg));
        sleep(1);
        sem_post(&w_sem);
    }    
    pthread_exit(0);      //主线程结束
}

int main(){
    //------------------------信号量互斥--------------------
    int num1=0, ret1;
    pthread_t thread1, thread2;

    sem_init(&w_sem, 0, 1);
    sem_init(&r_sem, 0, 0);
    ret1 = pthread_create(&thread1, NULL, fun1, (void *)&num1);
    if(ret1 != 0){
        perror("pthread_create1");
        exit(0);
    }
    ret1 = pthread_create(&thread2, NULL, fun2, (void *)&num1);
    if(ret1 != 0){
        perror("pthread_create2");
        exit(0);
    }
    printf("=================== main end ================\n");
    pthread_exit(0);      //主线程结束
}

喜羊羊系列之【 线程 】互斥锁+信号量

原文：http://blog.csdn.net/muyang_ren/article/details/45250551