通过多线程并发方式（fork）实现服务器

 与多进程实现对比来看。

示例来源于网络视频

#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <ctype.h>
#include <unistd.h>
#include <fcntl.h>
 
#include "wrap.h"
 
#define MAXLINE 8192
#define SERV_PORT 8000
 
struct s_info {                     //定义一个结构体, 将地址结构跟cfd捆绑
    struct sockaddr_in cliaddr;
    int connfd;
};
 
void *do_work(void *arg)
{
    int n,i;
    struct s_info *ts = (struct s_info*)arg;
    char buf[MAXLINE];
    char str[INET_ADDRSTRLEN];      //#define INET_ADDRSTRLEN 16  可用"[+d"查看
 
    while (1) {
        n = Read(ts->connfd, buf, MAXLINE);                     //读客户端
        if (n == 0) {
            printf("the client %d closed...\n", ts->connfd);
            break;                                              //跳出循环,关闭cfd
        }
        printf("received from %s at PORT %d\n",
                inet_ntop(AF_INET, &(*ts).cliaddr.sin_addr, str, sizeof(str)),
                ntohs((*ts).cliaddr.sin_port));                 //打印客户端信息(IP/PORT)
 
        for (i = 0; i < n; i++) 
            buf[i] = toupper(buf[i]);                           //小写-->大写
 
        Write(STDOUT_FILENO, buf, n);                           //写出至屏幕
        Write(ts->connfd, buf, n);                              //回写给客户端
    }
    Close(ts->connfd);
 
    return (void *)0;
}
 
int main(void)
{
    struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    int listenfd, connfd;
    pthread_t tid;
    struct s_info ts[256];      //根据最大线程数创建结构体数组.
    int i = 0;
 
    listenfd = Socket(AF_INET, SOCK_STREAM, 0);                     //创建一个socket, 得到lfd
 
    bzero(&servaddr, sizeof(servaddr));                             //地址结构清零
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);                   //指定本地任意IP
    servaddr.sin_port = htons(SERV_PORT);                           //指定端口号 8000
 
    Bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)); //绑定
 
    Listen(listenfd, 128);      //设置同一时刻链接服务器上限数
 
    printf("Accepting client connect ...\n");
 
    while (1) {
        cliaddr_len = sizeof(cliaddr);
        connfd = Accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);   //阻塞监听客户端链接请求
        ts[i].cliaddr = cliaddr;
        ts[i].connfd = connfd;
 
        /* 达到线程最大数时，pthread_create出错处理, 增加服务器稳定性 */
        pthread_create(&tid, NULL, do_work, (void*)&ts[i]);
        pthread_detach(tid);                                                    //子线程分离,防止僵线程产生.
        i++;
    }
 
    return 0;
}