实现TCP并发服务器之一（多进程）

下面用多进程方式实现一个TCP并发服务器，每当一个新的客户端连接时fork一个子进程去和它通信。（各种主流的web服务器都不是纯粹的多进程方式运行，比如apache在每个进程中都用多路复用方式，直到连接数多到超过select可监听的最大描述符数时也会利用新的进程去处理。）

服务器端（server.c）

#include<stdio.h>#include<stdlib.h>#include<string.h>#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#define MAX_LISTEN 5#define PORT 1987#define IP "127.0.0.1"void serve_proc(int conn_fd){int recv_num;int send_num;char recv_buf[100];char send_buf[100];int pid = getpid();printf("client %d started\n", pid);while (1) {//receiverecv_num = recv(conn_fd, recv_buf, sizeof(recv_buf), 0);if (recv_num < 0) {close(conn_fd);exit(1);}recv_buf[recv_num] = '\0';printf("child proc %d got : %s\n", pid, recv_buf);if (strcmp(recv_buf,"quit") == 0) {printf("child proc %d quit\n", pid);break;}//sendsprintf(send_buf, "server proc got %d bytes\n", recv_num);send_num = send(conn_fd, send_buf, strlen(send_buf), 0);if (send_num < 0) {close(conn_fd);exit(1);}printf("child proc %d sent : %s\n", pid, send_buf);}close(conn_fd);}int main(){pid_t pid;int conn_fd;int sock_fd = socket(AF_INET,SOCK_STREAM,0);if (sock_fd < 0) {perror("create socket failed");exit(1);}struct sockaddr_in addr_client;int client_size = sizeof(struct sockaddr_in);struct sockaddr_in addr_serv;memset(&addr_serv, 0, sizeof(addr_serv));addr_serv.sin_family = AF_INET;addr_serv.sin_port = htons(PORT);addr_serv.sin_addr.s_addr = inet_addr(IP);if (bind(sock_fd,(struct sockaddr *)&addr_serv,sizeof(struct sockaddr_in)) < 0) {perror("bind error");exit(1);}if (listen(sock_fd,MAX_LISTEN) < 0) {perror("listen failed");exit(1);}while (1) {conn_fd = accept(sock_fd, (struct sockaddr *)&addr_client, &client_size);if (conn_fd < 0) {perror("accept failed");exit(1);}pid = fork();if (pid == 0) { // child proc close(sock_fd);serve_proc(conn_fd);} else { // main procclose(conn_fd);}}close(sock_fd);return 0;}

客户端（client.c）

#include<stdio.h>#include<stdlib.h>#include<string.h>#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#define REMOTE_IP "127.0.0.1"#define REMOTE_PORT 1987int main(){        int sock_fd = socket(AF_INET, SOCK_STREAM, 0);        if (sock_fd < 0) {                perror("create socket failed");                exit(1);        }        struct sockaddr_in addr_serv;        memset(&addr_serv, 0 ,sizeof(addr_serv));        addr_serv.sin_family = AF_INET;        addr_serv.sin_port = htons(REMOTE_PORT);        addr_serv.sin_addr.s_addr = inet_addr(REMOTE_IP);        if (connect(sock_fd, (struct sockaddr *)&addr_serv, sizeof(struct sockaddr)) < 0) {                perror("connect failed");                exit(1);        }        int send_num, recv_num;        char send_buf[100],recv_buf[100];        while (1) {                printf("Input MSG: ");                scanf("%s",send_buf);                send_num = send(sock_fd, send_buf, strlen(send_buf), 0);                if (send_num < 0) {                        perror("send error");                        exit(1);                }                recv_num = recv(sock_fd, recv_buf, sizeof(recv_buf), 0);                if (recv_num < 0) {                        perror("recv error");                        exit(1);                }                recv_buf[recv_num] = '\0';                printf("Got : %s\n", recv_buf);        }        close(sock_fd);        return 0;}

代码都很简单啦，就是基本的收发数据。不过需要注意的一点是fork子进程以后需要对子进程关闭监听套接口，对父进程关闭连接套接口。