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（本文为bin学习网文《linux下的多线程编程》（作者：姚继锋 2001-08-11 09:05:00 来自：http://www.china-pub.com）时写下的摘要和学习笔记，特此声明，after1000years.com）

pthread_attr_t是存放线程属性的数据结构（pthread_create()的第二个参数）不能直接修改，需要通过调用各种前缀为pthread_attr_的函数来修改。

1. pthread_attr_setscope(pthread_attr_t *attr, int scopestate)（线程绑定函数）

系统控制线程是通过轻进程来实现的，一个轻进程可以控制一个或多个线程。绑定的好处就是线程具有较高的响应度，在需要的时候总有一个轻进程可以为之所用。

实现：

#include <pthread.h>
pthread_attr_t attr;
pthread_t tid;

/*初始化属性值，均设为默认值*/
pthread_attr_init(&attr);
pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);//第二个参数还有一个选项是PTHREAD_SCOPE_PROCESS（非绑定的）

pthread_create(&tid, &attr, (void *) my_function, NULL);

2. pthread_attr_setdetachstate（pthread_attr_t *attr, int detachstate）（线程分离函数）

如上篇文章所示的例子，pthread_join可以等到线程返回，这个线程与父线程未分离，如果设置了分离，则pthread_join无法等到这个线程了，父线程执行完毕之后直接就释放资源，结束了。（暂时想不出哪里用的上，因为完全可以设置为不分离，然后也不用join，直接让父线程跑掉就可以实现相同效果。）

例子:

#include <stdio.h>
#include <pthread.h>
#include <sys/time.h>
using namespace std;

void thread(void) {
struct timeval now;
struct timezone tz;
struct timespec timeout;

/*
timeout.tv_sec = time(0)+ 10;
timeout.tv_nsec = 0;
*/
gettimeofday(&now, &tz);
timeout.tv_sec = now.tv_sec + 5;
timeout.tv_nsec = now.tv_usec * 1000;

pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER;

pthread_cond_timedwait(&cond, &mut, &timeout);
pthread_mutex_unlock(&mut);
for(int i = 0; i < 3; i++) {
printf(”this is a pthread!\n”);
}
// pthread_exit(NULL);
}

int main() {
pthread_t id;
pthread_attr_t attr;

pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
int ret = pthread_create(&id, &attr, (void* (*)(void*))thread, NULL);
if(ret != 0) {
printf(”create pthread error!\n”);
exit(1);
}

for(int i = 0; i < 3; i++) {
printf(”this is main thread!\n”);
}
printf(”test1\n”);

// pthread_join(id, NULL);

printf(”test2\n”);

return EXIT_SUCCESS;
}

贴上网友一个很有意思的例子：原文地址

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

void* task1(void*);
void* task2(void*);

int main()
{
pthread_t pid1, pid2;
pthread_attr_t attr;
int ret;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
pthread_create(&pid1, &attr, task1, NULL);
ret=pthread_join(pid1, NULL);
printf(”ret=%d\n”, ret);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
pthread_create(&pid2, &attr, task2, NULL);
ret=pthread_join(pid2, NULL);
printf(”ret=%d\n”, ret);
return 1;
}

void* task1(void*)
{
printf(”task1\n”);
pthread_exit(NULL);
}

void* task2(void*)
{
pthread_detach(pthread_self());
printf(”task2\n”);
pthread_exit(NULL);
}

3. pthread_attr_getschedparam和pthread_attr_setschedparam（线程优先级设置函数）

#include <pthread.h>
#include <sched.h>
pthread_attr_t attr;
pthread_t tid;
sched_param param;
int newprio=20;

pthread_attr_init(&attr);
pthread_attr_getschedparam(&attr, &param);
param.sched_priority=newprio;
pthread_attr_setschedparam(&attr, &param);
pthread_create(&tid, &attr, (void *)myfunction, NULL);

1. extern int pthread_create (pthread_t *__restrict __newthread,
__const pthread_attr_t *__restrict __attr,
void *(*__start_routine) (void *),
void *__restrict __arg) __THROW __nonnull ((1, 3));

/* Create a new thread, starting with execution of START-ROUTINE getting passed ARG. Creation attributed come from ATTR. The new handle is stored in *NEWTHREAD. */

2. extern void pthread_exit (void *__retval) __attribute__ ((__noreturn__));

/* Terminate calling thread. The registered cleanup handlers are called via exception handling so we cannot mark this function with __THROW.*/

3. extern int pthread_join (pthread_t __th, void **__thread_return);

/* Make calling thread wait for termination of the thread TH. The exit status of the thread is stored in *THREAD_RETURN, if THREAD_RETURN is not NULL. This function is a cancellation point and therefore not marked with __THROW. */

例子代码：
#include <stdio.h>
#include <pthread.h>

void thread(void) {
for(int i = 0; i < 3; i++) {
printf(”this is a pthread!\n”);
}
}

int main() {
pthread_t id;
int ret = pthread_create(&id, NULL, (void* (*)(void*))thread, NULL);
if(ret != 0) {
printf(”create pthread error!\n”);
exit(1);
}

for(int i = 0; i < 3; i++) {
printf(”this is main thread!\n”);
}

printf(”test1\n”);
pthread_join(id, NULL);
printf(”test2\n”);

return EXIT_SUCCESS;
}

pthread_t //线程标识