Linux多线程编程详解 [By: HarryAlex]

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

void *thread_function(void *arg);

char message[] = "Hello World!";

int main()
{
    int res;
    pthread_t a_thread;
    void *thread_result;

    res = pthread_create(&a_thread, NULL, thread_function, (void *)message);
    if(res != 0) {
        perror("\nThread creation failed!\n");
        exit(EXIT_FAILURE);
    }

    printf("Waiting for thread to finish...\n");

    res = pthread_join(a_thread, &thread_result);
    if(res != 0) {
        perror("\nThread join failed!\n");
        exit(EXIT_FAILURE);
    }

    printf("Thread joined, it returned: %s\n", (char *)thread_result);
    printf("Message is now: %s\n", message);

    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg)
{
    printf("thread_function() is running. Argument is: %s\n", (char *)arg);
    sleep(3);
    strcpy(message, "Bye!");
    pthread_exit("Thank you for your CPU time!");
}

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

int flag = 1;
void *thread_function(void *arg);

int main()
{
    int res;
    pthread_t a_thread;
    void *thread_result;
    int count = 1;
    
    res = pthread_create(&a_thread, NULL, thread_function, NULL);
    if(res != 0) {
        perror("\nThread creation failed!\n");
        exit(EXIT_FAILURE);
    }

    while(count++ <= 10) {
        if(flag == 1) {
            printf("1");
            flag = 2;
        } else {
            sleep(1);
        }
    }

    printf("\nWaiting for thread to finish...\n");
    res = pthread_join(a_thread, &thread_result);
    if(res != 0) {
        perror("\nThread join failed!\n");
        exit(EXIT_FAILURE);
    }
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg)
{
    int count = 1;
    while(count++ <= 10) {      /* 不共享进程的局部变量count */
        if(flag == 2) {         /* 共享进程的全局变量flag */
            printf("2");
            flag = 1;
        } else {
            sleep(1);
        }
    }
}

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

#define SIZE 1024
char buffer[SIZE] = {0};
void *thread_function(void *arg);
sem_t sem;

int main()
{
    int res;
    pthread_t a_thread;
    void *thread_result;

    res = sem_init(&sem, 0, 0);
    if(res != 0) {
        perror("\nSem init failed!\n");
        exit(EXIT_FAILURE);
    }

    res = pthread_create(&a_thread, NULL, thread_function, NULL);
    if(res != 0) {
        perror("\nThread create failed!\n");
        exit(EXIT_FAILURE);
    }

    printf("Input some text, Enter 'end' to finish: \n");

    while(scanf("%s", buffer)) {
        sem_post(&sem);
        if(strncmp("end", buffer, 3) == 0) {
            break;
        }
    }

    printf("Waiting for thread to finish...\n");

    res = pthread_join(a_thread, &thread_result);
    if(res != 0) {
        perror("\nThread join failed!\n");
        exit(EXIT_FAILURE);
    }

    printf("Thread join!\n");
    sem_destroy(&sem);
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg)
{
    sem_wait(&sem);
    while(strncmp("end", buffer, 3) != 0) {
        printf("You input %d characters/n", strlen(buffer));
        sem_wait(&sem);
    }
    pthread_exit(NULL);
}

与其他函数一样，成功时返回0，失败时将返回错误代码，但这些函数并不设置errno，所以必须对函数的返回代码进行检查。互斥量的属性设置这里不讨论，因此设置成NULL。我们用互斥量来重写刚才的代码如下(thread4.c):

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

#define SIZE 1024
char buffer[SIZE] = {0};
void *thread_function(void *arg);
pthread_mutex_t mutex;

int main()
{
    int res;
    pthread_t a_thread;
    void *thread_result;

    res = pthread_mutex_init(&mutex, NULL);
    if(res != 0) {
        perror("\nMutex init failed!");
        exit(EXIT_FAILURE);
    }

    res = pthread_create(&a_thread, NULL, thread_function, NULL);
    if(res != 0) {
        perror("\nThread create failed!");
        exit(EXIT_FAILURE);
    }

    printf("Input some text, Enter 'end' to finish: \n");

    while(1) {
        pthread_mutex_lock(&mutex);
        scanf("%s", buffer);
        pthread_mutex_unlock(&mutex);
        if(strncmp("end", buffer, 3) == 0) {
            break;
        }
        sleep(1);
    }

    res = pthread_join(a_thread, &thread_result);
    if(res != 0) {
        perror("\nThread join failed!");
        exit(EXIT_FAILURE);
    }

    printf("Thread joined\n");
    pthread_mutex_destroy(&mutex);
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg)
{
    sleep(1);
    while(1) {
        pthread_mutex_lock(&mutex);
        printf("You input %d characters\n", strlen(buffer));
        pthread_mutex_unlock(&mutex);
        if(strncmp("end", buffer, 3) == 0) {
            break;
        }
        sleep(1);
    }
}

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

void *thread_function(void *arg);

char message[] = "Hello World!";
int thread_finished = 0;

int main()
{
    int res;
    pthread_t a_thread;
    pthread_attr_t thread_attr;
    
    res = pthread_attr_init(&thread_attr);
    if(res != 0) {
        perror("\nAttribute creation failed!\n");
        exit(EXIT_FAILURE);
    }
    
    res = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);  // 分离于主线程
    if(res != 0) {
        perror("\nSetting detached attribute failed!\n");
        exit(EXIT_FAILURE);
    }
    
    res = pthread_create(&a_thread, &thread_attr, thread_function, (void *)message);
    if(res != 0) {
        perror("\nThread creation failed!\n");
        exit(EXIT_FAILURE);
    }
    
    pthread_attr_destroy(&thread_attr);
    while(!thread_finished) {
        printf("Waiting for thread to say it's finished...\n");
        sleep(1);
    }
    
    printf("Other thread finished, Bye!\n");
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg)
{
    printf("thread_function() is running. Argument was %s\n", (char *)arg);
    sleep(4);
    printf("Second thread setting finished flag, and exiting now\n");
    thread_finished = 1;
    pthread_exit(NULL);
}

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

void *thread_function(void *arg);

int main()
{
    int res;
    pthread_t a_thread;
    void *thread_result;

    res = pthread_create(&a_thread, NULL, thread_function, NULL);
    if(res != 0) {
        perror("\nThread create failed!\n");
        exit(EXIT_FAILURE);
    }

    sleep(4);
    printf("Canceling thread...\n");

    res = pthread_cancel(a_thread);
    if(res != 0) {
        perror("\nThread cancel failed!\n");
        exit(EXIT_FAILURE);
    }

    printf ("Waiting for thread to finished...\n");
    
    res = pthread_join(a_thread, &thread_result);
    if(res != 0) {
        perror ("\nThread join failed!\n");
        exit(EXIT_FAILURE);
    }

    printf("Thread canceled!");
    exit(EXIT_FAILURE);
}

void *thread_function(void *arg)
{
    int i;
    int res;

    res = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);  // 可以被取消
    if(res != 0) {
        perror("\nThread setcancelstate failed!\n");
        exit(EXIT_FAILURE);
    }

    res = pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);  // 等待阻塞后再结束
    if(res != 0) {
        perror("\nThread setcanceltype failed!\n");
        exit(EXIT_FAILURE);
    }

    printf("thread_function is running...\n");

    for(i = 0; i < 10; i++) {
        printf("Thread is still running (%d)...\n", i);
        sleep(1);
    }
    pthread_exit(0);
}

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

#define  NUM     6

void *thread_function(void *arg);

int main()
{
    int res;
    pthread_t a_thread[NUM];
    void *thread_result;
    int index;

    for(index = 0; index < NUM; index++) {
        res = pthread_create(&a_thread[index], NULL, thread_function, (void *)index);
        if(res != 0) {
            perror("\nThread create failed!\n");
            exit(EXIT_FAILURE);
        }
        sleep(1);
    }

    printf("Waiting for threads to finished...\n");

    for(index = NUM - 1; index >= 0; index--) {
        res = pthread_join(a_thread[index], &thread_result);
        if(0 == res) {
            printf("Picked up a thread:%d\n", index + 1);
        } else {
            perror("\npthread_join failed!\n");
        }
    }

    printf("All done\n");
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg)
{
    int my_number = (int)arg;
    int rand_num;

    printf("thread_function is running. Argument was %d\n", my_number);
    rand_num = 1 + (int)(9.0 * rand()/(RAND_MAX + 1.0));
    sleep(rand_num);
    printf("Bye from %d\n", my_number);
    pthread_exit(NULL);
}

本文主要介绍了Linux环境下的多线程编程，介绍了信号量和互斥量、线程属性控制、线程同步、线程终止、取消线程及多线程并发。本文只作为Linux多线程编程入门之用。

Linux多线程编程详解 [By: HarryAlex]

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原文地址：http://blog.csdn.net/shr986796621/article/details/51023997