网络服务器处理阻塞问题

最近客户采用采用多个进程来同时对snmp服务器来set/get  ，有时候会造成网络服务器 net-snmp 的阻塞而无服务器反馈信息

为了改善，自己写了一个简单服务器，为了提高处理效果，创建子进程来处理，并由父进程来回收

代码如下：

头文件：

socket_include.h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

server.c

#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include "socket_include.h"

#define MAXLINE 80
#define SERV_PORT 1234

struct serialdata{
	int cur[10][24];
	int mincur[10][24];
	int maxcur[10][24];
	int minTcur[10][3];
	int maxTcur[10][3];
	int minTvol[10][3];
	int maxTvol[10][3];
	int minTH[10][8];
	int maxTH[10][8];
	int Tcur[10][3];
	int Tvol[10][3];
	int temp[10][4];
	int hum[10][4];
	int water[10];
	int smoke[10];
	int door[10][2];
	int kwh[10][24];
	int Tpowerfactor[10][3];
	int Tkwh[10][3];
	int swicth[10][24];
	int outputnum[10];
	int online[10];
	int type[10];
	int m_s;
	int alramflag[10][24+3+3+9];//output cur vol th
	////////////////////////////////////////////////
	int numperswicth[6];
	int ondelaytime;
	int offdelaytime;
	char slavename[10][32];
	char outputname[10][24][32];

};

struct serialdata *memdata;
struct serialdata *shmdata()
{
	key_t shmkey;
	int shmid;
	shmkey=ftok("/",‘b‘);
	shmid=shmget(shmkey,sizeof(struct serialdata)*2,0666|IPC_CREAT);
	if(shmid==-1)
		return NULL;
	struct serialdata * addr;
		addr=(struct serialdata*)shmat(shmid,0,0);
	if(addr==(struct serialdata*)-1)
		return NULL;
	return addr;
}

void handler(int num) {
    //我接受到了SIGCHLD的信号啦
    int status;
    int pid = waitpid(-1, &status, WNOHANG);
    if (WIFEXITED(status)) {
        printf("The child %d exit with code %d\n", pid, WEXITSTATUS(status));
    }
}   

int main()
{
	memdata = NULL;
	memdata = shmdata();
	if(memdata==NULL)
	{
		return -1;
	}
	//网络服务

	pid_t pid;
	struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    int listenfd, connfd;
    char buf[MAXLINE];
    char str[INET_ADDRSTRLEN];
    int i, n;
	int index=0;
	int outindex=0;

	char cmd1[256];
	char show[255];

    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);

        n = read(connfd, buf, MAXLINE);//读取网络数据

		buf[n]=‘\0‘;
        printf("received from %s at PORT %d,buf:%s\n",
         inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
         ntohs(cliaddr.sin_port),buf);

		signal(SIGCHLD, handler); 

		pid=fork();
        if(pid<0)
        {

              perror("fork error");

        }
        else if(pid==0)//子进程处理数据
        {

		for(index=0;index<10;index++)
		{
			for(outindex=0;outindex<24;outindex++)
				{
						memset(cmd1,0,sizeof(char)*255);
						sprintf(cmd1,"OFF %d %d",index,outindex+1);
						if(strcmp(cmd1,buf)==0)
						{
							printf("is in readcmd succed!\n");
							char sworder[255];

							//关输出位
							for(n=0;n<2;n++)
							{
								memdata->swicth[index][outindex]=1;
								memset(sworder,0,sizeof(char)*255);
								printf("\n");
								sprintf(sworder,"/clever/bin/order %d %d 2 1",index,outindex+1);
								system(sworder);
								printf("the off order is dnoe.\n");
								printf("\n");
							}
							break;
						}

						memset(cmd1,0,sizeof(char)*255);
						sprintf(cmd1,"ON %d %d",index,outindex+1);
						if(strcmp(cmd1,buf)==0)
						{
							printf("is in readcmd succed!\n");

							//关输出位
							char sworder[255];
							for(n=0;n<2;n++)
							{
								memdata->swicth[index][outindex]=2;
								memset(sworder,0,sizeof(char)*255);
								printf("\n");
								sprintf(sworder,"/clever/bin/order %d %d 1 1",index,outindex+1);
								system(sworder);
								printf("the on order is dnoe.\n");
								printf("\n");
							}
							break;
						}

						memset(cmd1,0,sizeof(char)*255);
						sprintf(cmd1,"status %d %d",index,outindex+1);
						if(strcmp(cmd1,buf)==0)
						{
							memset(show,0,sizeof(char)*255);
							sprintf(show,"status:%s\n",memdata->swicth[index][outindex]==0?"--":
									(memdata->swicth[index][outindex]==1?"OFF":"ON"));
							write(connfd, show, strlen(show));
							break;
						}
				}
		}
		//处理完成

			 write(connfd, "exit sucessed!\n", strlen("exit sucessed!\n"));
			close(connfd);//短连接结束
            exit(0);
		}

/*
		for (i = 0; i < n; i++)
            buf[i] = toupper(buf[i]);
		write(connfd, buf, n);
*/
	   //write(connfd, "exit sucessed!\n", strlen("exit sucessed!\n"));
	  // close(connfd);

    }

	return 0;

}

客户端：　

#include "socket_include.h"

#define MAXLINE 80
#define SERV_PORT 1234

int main(int argc, char *argv[])
{
    struct sockaddr_in servaddr;
    char buf[MAXLINE];
    int sockfd, n;
    char *str;

    if (argc != 2) {
        fputs("usage: ./client message\n", stderr);
        exit(1);
    }
    str = argv[1];

    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);
    inet_pton(AF_INET, "192.168.1.239", &servaddr.sin_addr);
    servaddr.sin_port = htons(SERV_PORT);

    connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

    write(sockfd, str, strlen(str));

    n = read(sockfd, buf, MAXLINE);
	buf[n]=‘\0‘;
    printf("Response from server:%s\n",buf);

    //write(STDOUT_FILENO, buf, n);

    close(sockfd);
    return 0;
}

测试程序：

#include <stdio.h>

int main()
{
	int i=0;
	for(i=0;i<100;i++)
	{
		printf("./client ‘ON 0 9‘\n");
		system("./client ‘ON 0 9‘");
		sleep(1);

		system("./client ‘status 0 9‘");
		sleep(1);

		printf("./client ‘OFF 0 9‘\n");
		system("./client ‘OFF 0 9‘");
		sleep(1);

		system("./client ‘status 0 9‘");
		sleep(1);

	}

	return 0;
}