简介

POSIX thread 简称为pthread，Posix线程是一个


POSIX


标准线程.该标准定义内部API创建和操纵线程.

作用

线程库实行了POSIX线程标准通常称为pthreads.pthreads是最常用的POSIX系统如Linux和Unix,而微软Windowsimplementations同时存在.举例来说,pthreads-w32可支持MIDP的pthread

Pthreads定义了一套 C程序语言类型、函数与常量，它以 pthread.h 头文件和一个线程库实现。

数据类型

pthread_t：线程句柄

pthread_attr_t：线程属性

线程操纵函数（简介起见，省略参数）

pthread_create()：创建一个线程

pthread_exit()：终止当前线程

pthread_cancel()：中断另外一个线程的运行

pthread_join()：阻塞当前的线程，直到另外一个线程运行结束

pthread_attr_init()：初始化线程的属性

pthread_attr_setdetachstate()：设置脱离状态的属性（决定这个线程在终止时是否可以被结合）

pthread_attr_getdetachstate()：获取脱离状态的属性

pthread_attr_destroy()：删除线程的属性

pthread_kill()：向线程发送一个信号

同步函数

用于 mutex 和条件变量

pthread_mutex_init() 初始化互斥锁

pthread_mutex_destroy() 删除互斥锁

pthread_mutex_lock()：占有互斥锁（阻塞操作）

pthread_mutex_trylock()：试图占有互斥锁（不阻塞操作）。当互斥锁空闲时将占有该锁；否则立即返回

pthread_mutex_unlock(): 释放互斥锁

pthread_cond_init()：初始化条件变量

pthread_cond_destroy()：销毁条件变量

pthread_cond_wait(): 等待条件变量的特殊条件发生

pthread_cond_signal(): 唤醒第一个调用pthread_cond_wait()而进入睡眠的线程

Thread-local storage（或者以Pthreads术语，称作

线程特有数据

）:

pthread_key_create(): 分配用于标识进程中线程特定数据的键

pthread_setspecific(): 为指定线程特定数据键设置线程特定绑定

pthread_getspecific(): 获取调用线程的键绑定，并将该绑定存储在 value 指向的位置中

pthread_key_delete(): 销毁现有线程特定数据键

与一起工作的工具函数

pthread_equal(): 对两个线程的线程标识号进行比较

pthread_detach(): 分离线程

pthread_self(): 查询线程自身线程标识号

详细请参见：

Linux多线程pthread：

http://blog.csdn.net/Sunboy_2050/archive/2010/10/04/5920936.aspx

Pthread多线程学习小结：

http://blog.csdn.net/Sunboy_2050/archive/2010/10/04/5921003.aspx

===================================================================

多线程创建

参考代码：

<br /> #include<stdio.h><br /> #include<pthread.h><br /> #include<string.h><br /> #include<sys/types.h><br /> #include<unistd.h><br /> pthread_t main_tid;<br /> void print_ids(const char *str)<br /> {<br /> pid_t pid; //进程id<br /> pthread_t tid; //线程id<br /> pid = getpid(); //获取当前进程id<br /> tid = pthread_self(); //获取当前线程id<br /> printf("%s pid: %u tid: %u (0x%x)/n",<br /> str,<br /> (unsigned int)pid,<br /> (unsigned int)tid,<br /> (unsigned int)tid);<br /> }<br /> void *func(void *arg)<br /> {<br /> print_ids("new thread:");<br /> return ((void *)0);<br /> }<br /> int main()<br /> {<br /> int err;<br /> err = pthread_create(&main_tid, NULL, func, NULL); //创建线程<br /> if(err != 0){<br /> printf("create thread error: %s/n",strerror(err));<br /> return 1;<br /> }<br /> printf("main thread: pid: %u tid: %u (0x%x)/n",<br /> (unsigned int)getpid(),<br /> (unsigned int)pthread_self(),<br /> (unsigned int)pthread_self());<br /> print_ids("main thread:");<br /> sleep(1);<br /> return 0;<br /> }<br />

运行结果：

[work@db-testing-com06-vm3.db01.baidu.com pthread]$ gcc -Wall -o pthread_create pthread_create.c -lpthread

[work@db-testing-com06-vm3.db01.baidu.com pthread]$ ./pthread_create

main thread: pid: 12531 tid: 2505487232 (0x9556b380)

main thread: pid: 12531 tid: 2505487232 (0x9556b380)

new  thread: pid: 12531 tid: 1084229984 (0x40a00960)

===================================================================

多线程条件变量

参考代码：

<br /> #include <stdio.h><br /> #include <pthread.h><br /> #include <unistd.h></p> <p>pthread_mutex_t counter_lock; //互斥锁<br /> pthread_cond_t counter_nonzero; //条件变量<br /> int counter = 0;<br /> int estatus = -1;</p> <p>void *decrement_counter(void *argv);<br /> void *increment_counter(void *argv);</p> <p>//******* 主函数 *******//<br /> int main(int argc, char **argv)<br /> {<br /> printf("counter: %d/n", counter);<br /> pthread_t thd1, thd2;<br /> int ret;</p> <p> //初始化<br /> pthread_mutex_init(&counter_lock, NULL);<br /> pthread_cond_init(&counter_nonzero, NULL);</p> <p> ret = pthread_create(&thd1, NULL, decrement_counter, NULL); //创建线程1<br /> if(ret){<br /> perror("del:/n");<br /> return 1;<br /> }</p> <p> ret = pthread_create(&thd2, NULL, increment_counter, NULL); //创建线程2<br /> if(ret){<br /> perror("inc: /n");<br /> return 1;<br /> }</p> <p> int counter = 0;<br /> while(counter != 10){<br /> printf("counter(main): %d/n", counter); //主线程<br /> sleep(1);<br /> counter++;<br /> }</p> <p> pthread_exit(0);</p> <p> return 0;<br /> }</p> <p>void *decrement_counter(void *argv)<br /> {<br /> printf("counter(decrement): %d/n", counter);<br /> pthread_mutex_lock(&counter_lock);<br /> while(counter == 0)<br /> pthread_cond_wait(&counter_nonzero, &counter_lock); //进入阻塞(wait)，等待激活(signal)</p> <p> printf("counter--(before): %d/n", counter);<br /> counter--; //等待signal激活后再执行<br /> printf("counter--(after): %d/n", counter);<br /> pthread_mutex_unlock(&counter_lock); </p> <p> return &estatus;<br /> }</p> <p>void *increment_counter(void *argv)<br /> {<br /> printf("counter(increment): %d/n", counter);<br /> pthread_mutex_lock(&counter_lock);<br /> if(counter == 0)<br /> pthread_cond_signal(&counter_nonzero); //激活(signal)阻塞(wait)的线程(先执行完signal线程，然后再执行wait线程)</p> <p> printf("counter++(before): %d/n", counter);<br /> counter++;<br /> printf("counter++(after): %d/n", counter);<br /> pthread_mutex_unlock(&counter_lock);</p> <p> return &estatus;<br /> }<br />

运行结果：

[work@db-testing-com06-vm3.db01.baidu.com pthread]$ gcc -Wall -o pthread_cond2 pthread_cond2.c -lpthread

[work@db-testing-com06-vm3.db01.baidu.com pthread]$ ./pthread_cond2

counter: 0

counter(main): 0

counter(decrement): 0

counter(increment): 0

counter++(before): 0

counter++(after): 1

counter--(before): 1

counter--(after): 0

counter(main): 1

counter(main): 2

counter(main): 3

counter(main): 4

counter(main): 5

counter(main): 6

counter(main): 7

counter(main): 8

counter(main): 9

详细解释

，请见：

http://blog.csdn.net/Sunboy_2050/archive/2010/11/24/6031723.aspx

===================================================================

多线程的创建特殊数据键

参考代码：

<br /> #include <stdio.h><br /> #include <pthread.h><br /> #include <unistd.h></p> <p>pthread_key_t key; //声明参数key</p> <p>void echomsg(void *arg) //析构处理函数<br /> {<br /> printf("destruct executed in thread = %u, arg = %p/n",<br /> (unsigned int)pthread_self(),<br /> arg);<br /> }</p> <p>void *child_1(void *arg)<br /> {<br /> pthread_t tid;</p> <p> tid = pthread_self();<br /> printf("%s: thread %u enter/n", (char *)arg, (unsigned int)tid);</p> <p> pthread_setspecific(key, (void *)tid); // 与key值绑定的value(tid)<br /> printf("%s: thread %u returns %p/n", // %p 表示输出指针格式<br /> (char *)arg,<br /> (unsigned int)tid,<br /> pthread_getspecific(key)); // 获取key值的value<br /> sleep(1);<br /> return NULL;<br /> }</p> <p>void *child_2(void *arg)<br /> {<br /> pthread_t tid;</p> <p> tid = pthread_self();<br /> printf("%s: thread %u enter/n", (char *)arg, (unsigned int)tid);</p> <p> pthread_setspecific(key, (void *)tid);<br /> printf("%s: thread %u returns %p/n",<br /> (char *)arg,<br /> (unsigned int)tid,<br /> pthread_getspecific(key));<br /> sleep(1);<br /> return NULL;<br /> }</p> <p>//******* 主函数 *******//<br /> int main(void)<br /> {<br /> pthread_t tid1, tid2;</p> <p> printf("hello main/n");</p> <p> pthread_key_create(&key, echomsg); //创建key</p> <p> pthread_create(&tid1, NULL, child_1, (void *)"child_1"); //创建带参数的线程，需要强制转换<br /> pthread_create(&tid2, NULL, child_2, (void *)"child_2");</p> <p> sleep(3);<br /> pthread_key_delete(key); //清除key<br /> printf("bye main/n");</p> <p> pthread_exit(0);<br /> return 0;<br /> }<br />

运行结果：

[work@db-testing-com06-vm3.db01.baidu.com pthread]$ gcc -Wall -o pthread_setspecific pthread_setspecific.c -lpthread

[work@db-testing-com06-vm3.db01.baidu.com pthread]$ ./pthread_setspecific


hello main

child_1: thread 1084229984 enter

child_1: thread 1084229984 returns 0x40a00960

child_2: thread 1094719840 enter

child_2: thread 1094719840 returns 0x41401960

destruct executed in thread = 1084229984, arg = 0x40a00960

destruct executed in thread = 1094719840, arg = 0x41401960

bye main

附加参考——函数原型：

Posix定义了两个API分别用来创建和注销TSD：