linux多线程编程详解

注：如果unubtu下 man手册不全，需要安装 apt-get install manpages-posix-dev

一、线程创建

PTHREAD_CREATE(3)          Linux Programmer's Manual         PTHREAD_CREATE(3)NAME       pthread_create - create a new threadSYNOPSIS       #include <pthread.h>       int pthread_create(pthread_t *thread, const pthread_attr_t *attr,                          void *(*start_routine) (void *), void *arg);       Compile and link with -pthread.

返回值：若成功，返回0；否则，返回错误编码
参数：第二参数attr是线程的属性，可以设置为NULL使用默认属性

二、获取线程ID

PTHREAD_SELF(3)            Linux Programmer's Manual           PTHREAD_SELF(3)NAME       pthread_self - obtain ID of the calling threadSYNOPSIS       #include <pthread.h>       pthread_t pthread_self(void);       Compile and link with -pthread.

返回值：调用线程的线程ID

三、线程ID比较

PTHREAD_EQUAL(3)           Linux Programmer's Manual          PTHREAD_EQUAL(3)NAME       pthread_equal - compare thread IDsSYNOPSIS       #include <pthread.h>       int pthread_equal(pthread_t t1, pthread_t t2);       Compile and link with -pthread.

返回值：若相等，返回非0数值；否则，返回0

四、线程终止

PTHREAD_EXIT(3)            Linux Programmer's Manual           PTHREAD_EXIT(3)NAME       pthread_exit - terminate calling threadSYNOPSIS       #include <pthread.h>       void pthread_exit(void *retval);       Compile and link with -pthread.

retval参数是一个无类型的指针，进程中的其他线程也可以通过调用pthread_join访问到这个指针

五、阻塞等待指定线程退出

PTHREAD_JOIN(3)            Linux Programmer's Manual           PTHREAD_JOIN(3)NAME       pthread_join - join with a terminated threadSYNOPSIS       #include <pthread.h>       int pthread_join(pthread_t thread, void **retval);       Compile and link with -pthread.

返回值：若成功，返回0；否则，返回错误编码

注：如果线程已经处于分离状态，pthread_join就会处于调用失败。

六、取消同一进程中的其他线程

PTHREAD_CANCEL(3)          Linux Programmer's Manual         PTHREAD_CANCEL(3)NAME       pthread_cancel - send a cancellation request to a threadSYNOPSIS       #include <pthread.h>       int pthread_cancel(pthread_t thread);       Compile and link with -pthread.

返回值：若成功，返回0；否则，返回错误编码

注：线程可以选择忽略取消或者控制如何被取消。

七、分离线程函数

PTHREAD_DETACH(3)          Linux Programmer's Manual         PTHREAD_DETACH(3)NAME       pthread_detach - detach a threadSYNOPSIS       #include <pthread.h>       int pthread_detach(pthread_t thread);       Compile and link with -pthread.

返回值：若成功，返回0；否则，返回错误编码

一个比较完整的例子，用到了上面的7个函数：gcc pthread_create.c -pthread

#include <pthread.h>#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>void Perror(const char *s){    perror(s);    exit(EXIT_FAILURE);}void* fun2(void *arg){    pthread_t thread_id = pthread_self();    printf("the thread2 id is %ld, arg is %d\n", (long)thread_id, *(int*)arg);    sleep(1); /* wait for join */    pthread_exit((void*)2);}void* fun3(void *arg){    pthread_t thread_id = pthread_self();    printf("the thread3 id is %ld, arg is %d\n", (long)thread_id, *(int*)arg);    sleep(60); /* wait for cancel */}int main(){    int err;    pthread_t thread1;    pthread_t thread2;    pthread_t thread3;    int arg2 = 2;    int arg3 = 3;    thread1 = pthread_self();    printf("the thread1 id is %ld\n", (long)thread1);    // Create thread    err = pthread_create(&thread2, NULL, fun2, (void*)&arg2);    if (err != 0) {        Perror("can't create thread2\n");    }    err = pthread_create(&thread3, NULL, fun3, (void*)&arg3);    if (err != 0) {        Perror("can't create thread3\n");    }    // detach thread3    err = pthread_detach(thread3);    if (err != 0) {        Perror("can't detach thread3\n");    }    // if equal    if (pthread_equal(thread2, thread3) != 0)        printf("the thread2 and thread3 same\n");    else        printf("the thread2 and thread3 diff\n");    // wait thread2 exit    void *retval;    int res = pthread_join(thread2, &retval);    if (res != 0)        printf("can't join with thread2\n");    else        printf("thread2 exit code %ld\n", (long)retval);    // cancel thread3    err = pthread_cancel(thread3);    if (err != 0) {        Perror("can't cancel thread3\n");    }    sleep(60);    return 0;}

运行结果：

注：通过pstree命令也观察到线程数如程序设置一样。

参考：《unix环境高级编程》·第三版

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