[TOC] # 简介 使用多进程并发服务器时要考虑以下几点： 1. 父进程最大文件描述个数(父进程中需要close关闭accept返回的新文件描述符) 2. 系统内创建进程个数(与内存大小相关) 3. 进程创建过多是否降低整体服务性能(进程调度) # server ~~~ /* server.c */ #include <stdio.h> #include <string.h> #include <netinet/in.h> #include <arpa/inet.h> #include <signal.h> #include <sys/wait.h> #include <sys/types.h> #include "wrap.h" #define MAXLINE 80 #define SERV_PORT 800 void do_sigchild(int num) { while (waitpid(0, NULL, WNOHANG) > 0) ; } int main(void) { struct sockaddr_in servaddr, cliaddr; socklen_t cliaddr_len; int listenfd, connfd; char buf[MAXLINE]; char str[INET_ADDRSTRLEN]; int i, n; pid_t pid; struct sigaction newact; newact.sa_handler = do_sigchild; sigemptyset(&newact.sa_mask); newact.sa_flags = 0; sigaction(SIGCHLD, &newact, NULL); listenfd = Socket(AF_INET, SOCK_STREAM, 0); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(INADDR_ANY); servaddr.sin_port = htons(SERV_PORT); Bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)); Listen(listenfd, 20); printf("Accepting connections ...\n"); while (1) { cliaddr_len = sizeof(cliaddr); connfd = Accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len); pid = fork(); if (pid == 0) { Close(listenfd); while (1) { n = Read(connfd, buf, MAXLINE); if (n == 0) { printf("the other side has been closed.\n"); break; } printf("received from %s at PORT %d\n", inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)), ntohs(cliaddr.sin_port)); for (i = 0; i < n; i++) buf[i] = toupper(buf[i]); Write(connfd, buf, n); } Close(connfd); return 0; } else if (pid > 0) { Close(connfd); } else perr_exit("fork"); } Close(listenfd); return 0; } ~~~ # client ~~~ /* client.c */ #include <stdio.h> #include <string.h> #include <unistd.h> #include <netinet/in.h> #include "wrap.h" #define MAXLINE 80 #define SERV_PORT 6666 int main(int argc, char *argv[]) { struct sockaddr_in servaddr; char buf[MAXLINE]; int sockfd, n; sockfd = Socket(AF_INET, SOCK_STREAM, 0); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr); servaddr.sin_port = htons(SERV_PORT); Connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)); while (fgets(buf, MAXLINE, stdin) != NULL) { Write(sockfd, buf, strlen(buf)); n = Read(sockfd, buf, MAXLINE); if (n == 0) { printf("the other side has been closed.\n"); break; } else Write(STDOUT_FILENO, buf, n); } Close(sockfd); return 0; } ~~~