高并发服务器

多进程并发服务器

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(intnum)

{

   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 beenclosed.\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;

}

 

多线程并发服务器

在使用线程模型开发服务器时需考虑以下问题：

1.      调整进程内最大文件描述符上限

2.      线程如有共享数据，考虑线程同步

3.      服务于客户端线程退出时，退出处理。（退出值，分离态）

4.      系统负载，随着链接客户端增加，导致其它线程不能及时得到CPU

server

/* server.c */

#include <stdio.h>

#include<string.h>

#include<netinet/in.h>

#include<arpa/inet.h>

#include<pthread.h>

 

#include"wrap.h"

#define MAXLINE 80

#define SERV_PORT 6666

 

struct s_info {

   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];

   /*可以在创建线程前设置线程创建属性,设为分离态,哪种效率高内？ */

   pthread_detach(pthread_self());

   while (1) {

       n = Read(ts->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,&(*ts).cliaddr.sin_addr, str, sizeof(str)),

              ntohs((*ts).cliaddr.sin_port));

       for (i = 0; i < n; i++)

          buf[i] = toupper(buf[i]);

       Write(ts->connfd, buf, n);

   }

   Close(ts->connfd);

}

 

int main(void)

{

   struct sockaddr_in servaddr, cliaddr;

   socklen_t cliaddr_len;

   int listenfd, connfd;

   int i = 0;

   pthread_t tid;

   struct s_info ts[256];

 

   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);

      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]);

      i++;

   }

   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");

       else

          Write(STDOUT_FILENO, buf, n);

   }

   Close(sockfd);

   return 0;

}