深入理解计算机系统（第三版）第十二章重要内容摘要

12.1基于进程的并发编程

12.1.1基于进程的并发服务器

12.1.2进程的优劣

12.2基于I/O多路复用的并发编程

12.2.1基于I/O多路复用的并发事件驱动器

12.2.2I/O多路复用技术的优劣

优点

1、

2、

3、

4、

缺点

1、（）

2、

12.3基于线程的并发编程

12.3.1线程执行模型

12.3.2Posix线程

12.3.3创建线程

12.3.4终止线程

12.3.5回收已终止线程的资源

12.3.6分离线程

12.3.7初始化线程

12.3.8基于线程的并发服务器

12.4多线程程序的共享变量

12.4.1线程内存模型

12.4.2将变量映射到内存

12.4.3共享变量

12.5用信号量同步线程

// 
/* WARING: This code is buggy */  
#include "csapp.h"  
void thread(void vargp);  / thread routine prototype /
/ globle shared variable /

volatile long cnt = 0;  / counter /
int main(int argc, char **argv)

{

long niters;

pthread_t tid1, tid2;
</span><span style="color: #008000;">/*</span><span style="color: #008000;"> check input argument </span><span style="color: #008000;">*/</span>  
<span style="color: #0000ff;">if</span> (argc != <span style="color: #800080;">2</span><span style="color: #000000;">) {  
    printf(</span><span style="color: #800000;">"</span><span style="color: #800000;">usage: %s &lt;niters&gt;
</span><span style="color: #800000;">"</span>, argv[<span style="color: #800080;">0</span><span style="color: #000000;">]);  
    exit(</span><span style="color: #800080;">0</span><span style="color: #000000;">);  
}  
niters </span>= atoi(argv[<span style="color: #800080;">1</span><span style="color: #000000;">]);  
  
</span><span style="color: #008000;">/*</span><span style="color: #008000;"> create threads and wait for them to finish </span><span style="color: #008000;">*/</span><span style="color: #000000;">  
pthread_create(</span>&amp;tid1, NULL, thread, &amp;<span style="color: #000000;">niters);  
pthread_create(</span>&amp;tid2, NULL, thread, &amp;<span style="color: #000000;">niters);  
pthread_join(tid1, NULL);  
pthread_join(tid2, NULL);  
  
</span><span style="color: #008000;">/*</span><span style="color: #008000;"> check result </span><span style="color: #008000;">*/</span>  
<span style="color: #0000ff;">if</span> (cnt != (<span style="color: #800080;">2</span> *<span style="color: #000000;"> niters))  
    printf(</span><span style="color: #800000;">"</span><span style="color: #800000;">BOOM! cnt = %1d
</span><span style="color: #800000;">"</span><span style="color: #000000;">, cnt);  
</span><span style="color: #0000ff;">else</span><span style="color: #000000;">  
    printf(</span><span style="color: #800000;">"</span><span style="color: #800000;">OK cnt = %1d
</span><span style="color: #800000;">"</span><span style="color: #000000;">, cnt);  
exit(</span><span style="color: #800080;">0</span><span style="color: #000000;">);  

}
/ thread routine /

void *thread(void *vargp)

{

long i, niters = *((long *)vargp);
</span><span style="color: #0000ff;">for</span> (i = <span style="color: #800080;">0</span>; i &lt; niters; i++<span style="color: #000000;">)  
    cnt</span>++<span style="color: #000000;">;  
      
</span><span style="color: #0000ff;">return</span><span style="color: #000000;"> NULL;  

}

//