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我已经编写了一个基于套接字的多客户端服务器和一个客户端作为分配，但我似乎无法摆脱分叉的进程。每次我关闭客户端或输入退出命令时，进程似乎都没有关闭。检查时ps aux| grep server有一个缺陷进程。我怎样才能摆脱它们，关闭分叉的proses时我做错了什么。

服务器：

#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <time.h>

void error(char *msg)
{
    perror(msg);
    exit(1);
}

void doprocessing (int sock)
{
   int n;
   char buffer[5];
   time_t rawtime;
   char tim[22];
   char dat[20];
   char day[16];
   char yer[18];

   while(1)
   {
     bzero(buffer,5);
     n = read(sock,buffer,5);

     if (n < 0) error("ERROR reading from socket");

     printf("Got %.3s command.\n",buffer);

     if (strcasecmp(buffer, "tim\n") == 0)
     {
        rawtime = time(NULL);
        strncpy(tim, "Current time: ", 14);
        strncpy(tim+14, (ctime(&rawtime))+11, 8);
        n = write(sock, tim, 22);
     }
     else if (strcasecmp(buffer, "dat\n") == 0)
     {
        rawtime = time(NULL);
        strncpy(dat, "Current date: ", 14);
        strncpy(dat+14, (ctime(&rawtime))+4, 6);
        n = write(sock, dat, 20);
     }
     else if (strcasecmp(buffer, "day\n") == 0)
     {
        rawtime = time(NULL);
        strncpy(day, "Current day: ", 13);
        strncpy(day+13, (ctime(&rawtime)), 3);
        n = write(sock, day, 16);
     }
     else if (strcasecmp(buffer, "yer\n") == 0)
     {
        rawtime = time(NULL);
        strncpy(yer, "Current year: ", 14);
        strncpy(yer+14, (ctime(&rawtime))+20, 4);
        n = write(sock, yer, 18);
     }
     else if (strcasecmp(buffer, "com\n") == 0)
     {
        n = write(sock, "TIM - current time\nDAT - Month and day\nDAY - current weekday\nYER - Year\nEXT - exit", 82);
     }
     else if (strcasecmp(buffer, "ext\n") == 0)
     {
        n = write(sock, "Exiting", 7);
        break;
     }
     else  n = write(sock, "Wrong command enter COM to see commands.",40);

     if (n < 0) error("ERROR writing to socket");}
   }

int main(int argc, char *argv[])
{
    int sockfd, newsockfd, portno, clilen, n;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int pid;

    if (argc < 2)
    {
        fprintf(stderr, "ERROR, no port provided");
        exit(1);
    }

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) error("ERROR opening socket");

    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = atoi(argv[1]);

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(portno);
    serv_addr.sin_addr.s_addr = INADDR_ANY;

    if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) error("ERROR on binding");

    listen(sockfd, 5);
    clilen = sizeof(cli_addr);

    while(1)
    {
         newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
         if (newsockfd < 0) error("ERROR on accept");


         pid = fork();

         if (pid < 0) error("ERROR on fork");

         if (pid == 0)
         {
             close(sockfd);
             doprocessing(newsockfd);
             exit(-1);
         }
         else close(newsockfd);
    }
    close(sockfd);
    return 0;
}

客户端：

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

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char rbuffer[256];
    char sbuffer[256];

    if (argc < 3)
    {
       fprintf(stderr,"usage %s hostname port\n", argv[0]);
       exit(0);
    }

    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) error("ERROR opening socket");

    server = gethostbyname(argv[1]);

    if (server == NULL)
    {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
    serv_addr.sin_port = htons(portno);

    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) error("ERROR connecting");

    while(1)
    {
       printf("Enter a command: ");
       bzero(sbuffer,sizeof(sbuffer));
       fgets(sbuffer,255,stdin);
       n = write(sockfd,sbuffer,5);
       if (n < 0) error("ERROR writing to socket");

       bzero(rbuffer,sizeof(rbuffer));
       n = read(sockfd,rbuffer,255);
       if (n < 0) error("ERROR reading from socket");

       printf("%s\n",rbuffer);

       if (strcasecmp(sbuffer, "ext\n") == 0) break;
    }
    close(sockfd);
    return 0;
}
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1 回答 1

2

一个进程将在 ps 输出中显示为“已失效”（有时称为僵尸进程），直到它的退出状态将用wait()or收集waitpid()。

有以下方法可以摆脱那些僵尸进程：

  1. wait()使用或waitpid()在父进程中等待子进程完成。显然，很难以这种方式在父级中做任何其他事情。
  2. 在产生子节点后立即在waitpid该线程内创建一个单独的线程。
  3. 在您的父级中，为 SIGCHLD 信号安装一个处理程序并waitpid()在此处理程序内。
  4. 如果您的系统允许，请设置为忽略 SIGCHLD 信号。
于 2016-03-14T17:18:50.947 回答