多进程实现并发服务器
多进程并发服务器.c
架构
int sockfd = socket()
bian()
listen()
while(1){acceptfd = accept()pid = fork()if(pid > 0){}else if(pid == 0){while(1){recv()/send()}}
}
注意:accept不能放在 PID > 0 中,因为fork之后,子进程和父进程一点关系都没有,而recv和send都需要,accept函数的返回值,父子进程都只执行自己私有空间里的内容,所以需要把,accent放在,fork之前让子进程在创建的时候拷贝返回值过去(泪的教训)。
父进程保证永远都在accept的位置堵塞,当有客户端请求同步链接的时候,就会创建一个子进程,而子进程会一直在while(1)中,判断当有一个客户端关闭的时候,就关闭子进程 就行(即通过信号,异步的去处理僵尸进程)
案例
/*
# Multi-process concurrent server
# https://www.cnblogs.com/kencszqh
#
# File Name: 多进程并发.c
# Created : 2024/6/11
*/#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/epoll.h>
#include <pthread.h>
#include <semaphore.h>
#include <sys/mman.h>
#include <sys/eventfd.h>
#include <sys/timerfd.h>
#include <sys/signalfd.h>
#include <sys/syscall.h>
#include <sys/prctl.h>
#include <sys/uio.h>#define ERR_LOG(errmsg) \do \{ \perror(errmsg); \exit(1); \} while (0)#define N 128void handler(int sig)
{wait(NULL);
}int main(int argc, char const *argv[])
{if (argc < 3){fprintf(stderr, "Usage:%s [ip] [port]\n", argv[0]);exit(1);}int sockfd, acceptfd;struct sockaddr_in serveraddr, clientaddr;socklen_t addrlen = sizeof(serveraddr);// 1.创建套接字if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){ERR_LOG("fail to socket");}// 2.填充服务器网络信息结构体server_addr.sin_family = AF_INET;server_addr.sin_addr.s_addr = inet_addr(argv[1]);server_addr.sin_port = htons(atoi(argv[2]));// 3.绑定套接字if (bind(sockfd, (struct sockaddr *)&serveraddr, addrlen) < 0){ERR_LOG("fail to bind");}// 4.监听if (listen(sockfd, 5) < 0){ERR_LOG("fail to listen");}// 使用信号,异步的方式处理僵尸进程,并不会堵塞父进程signal(SIGCHLD, handler);while (1){// 5.阻塞等待客户端连接请求if ((acceptfd = accept(socket, (struct sockaddr *)&clientaddr, &addrlen)) < 0){ERR_LOG("fail to accept");}printf("cl ip:%s, port:%d\n", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));// 6.创建子进程pid_t pid;if ((pid = fork()) < 0){ERR_LOG("fail to fork");}else if (pid > 0) // 父进程负责执行accept,所以if语句结束后继续在accept函数的位置阻塞{}else // 子进程负责执行与客户端通信的代码{char buf[N] = {0};ssize_t bytes;while (1){if ((bytes = read(acceptfd, buf, N)) < 0){ERR_LOG("fail to read");}else if (bytes == 0){printf("fail to recv\n");exit(0);}if (strncmp(buf, "qaq", 4) == 0){printf("qaq\n");exit(0);}printf("recv:%s\n", buf);strcat(buf, " from server");if (send(acceptfd, buf, N, 0) < 0){ERR_LOG("fail to send");}}}}return 0;
}