我正在尝试创建并行服务器。它应该能够同时与多个客户端（通过telnet）一起工作。我使用fork（）创建子进程，使用pipe（）在父进程和子进程之间共享变量。我的问题是它只能同时允许一个连接，第二个必须等到第一个连接完成。我是新手，所以无法找到为什么我会顺序服务器而不是并行。
/*
* File: 3LD_parduotuve.c
* Author: zuykas
*
* Created on April 6, 2013, 4:33 PM
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#include <string.h>
#define PORT "1234"
#define BACKLOG 10
void sigchld_handler(int s) {
while (waitpid(-1, NULL, WNOHANG) > 0);
}
void *get_in_addr(struct sockaddr *sa) {
if (sa->sa_family == AF_INET) {
return &(((struct sockaddr_in*) sa)->sin_addr);
}
return &(((struct sockaddr_in6*) sa)->sin6_addr);
}
int main(void) {
int sockfd, new_fd;
struct addrinfo hints, *servinfo, *p;
struct sockaddr_storage their_addr;
socklen_t sin_size;
struct sigaction sa;
int yes = 1;
char s[INET6_ADDRSTRLEN];
int rv;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;
if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return 1;
}
for (p = servinfo; p != NULL; p = p->ai_next) {
if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) {
perror("server: socket");
continue;
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof (int)) == -1) {
perror("setsockopt");
exit(1);
}
if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
close(sockfd);
perror("server: bind");
continue;
}
break;
}
if (p == NULL) {
fprintf(stderr, "Serveris: failed to bind\n");
return 2;
}
freeaddrinfo(servinfo);
if (listen(sockfd, BACKLOG) == -1) {
perror("listen");
exit(1);
}
sa.sa_handler = sigchld_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if (sigaction(SIGCHLD, &sa, NULL) == -1) {
perror("sigaction");
exit(1);
}
printf("Serveris: laukiama prisijungimo\n");
//prekiu_sk is variable to be changed in child processes and saved in parent
int prekiu_sk = 100, tekstas, kl_zinute;
int kliento_sk;
char buffer[80];
int fd1[2];
pipe(fd1);
write(fd1[1],&prekiu_sk,sizeof(prekiu_sk));
while (1) {
sin_size = sizeof their_addr;
new_fd = accept(sockfd, (struct sockaddr *) &their_addr, &sin_size);
if (new_fd == -1) {
perror("accept");
continue;
}
inet_ntop(their_addr.ss_family,
get_in_addr((struct sockaddr *) &their_addr), s, sizeof s);
printf("Serveris: prisijungiama adresu %s\n", s);
if (!fork()) {
int skaicius;
read(fd1[0],&skaicius,sizeof(prekiu_sk));
close(sockfd);
if (skaicius<1)
{
tekstas = sprintf(buffer, "Sandelyje nebera prekiu.\nRysys nutraukiamas\n");
send(new_fd, buffer, tekstas, 0);
write(fd1[1],&skaicius, sizeof(skaicius));
//close(fd1[0]);
//close(fd1[1]);
close(new_fd);
exit(0);
}
tekstas = sprintf(buffer, "Siuo metu sandalyje uzregistruota %d prekiu.\n", skaicius);
send(new_fd, buffer, tekstas, 0);
tekstas = sprintf(buffer, "Iveskite isimamu prekiu skaiciu.\n");
send(new_fd, buffer, tekstas, 0);
kl_zinute = recv(new_fd, buffer, sizeof (buffer), 0);
kliento_sk = atoi(buffer);
if ((kliento_sk<1) || (kliento_sk>skaicius))
{
tekstas = sprintf(buffer, "Neteisingai ivestas isimamu prekiu skaicius.\nRysys nutraukiamas\n");
send(new_fd, buffer, tekstas, 0);
write(fd1[1],&skaicius, sizeof(skaicius));
//close(fd1[0]);
//close(fd1[1]);
close(new_fd);
exit(0);
}
printf("%d \n %d \n %d", *fd1, kl_zinute, kliento_sk);
//read(fd1[0],&skaicius,sizeof(prekiu_sk));
if (skaicius<kliento_sk)
{
tekstas = sprintf(buffer, "Likutis sandelyje nepakankamas.\n "
"Kazkas pries jus sumazino prekiu kieki.\n"
"Rysys nutraukiamas\n");
send(new_fd, buffer, tekstas, 0);
write(fd1[1],&skaicius, sizeof(skaicius));
//close(fd1[0]);
//close(fd1[1]);
close(new_fd);
exit(0);
}
skaicius = skaicius - kliento_sk;
printf("%d",atoi(buffer));
tekstas = sprintf(buffer, "Liko %d prekiu \n", skaicius);
send(new_fd, buffer, tekstas, 0);
write(fd1[1],&skaicius, sizeof(skaicius));
printf("%d child %d",*fd1, skaicius);
//close(fd1[0]);
//close(fd1[1]);
close(new_fd);
exit(0);
}
//wait(NULL);
read(fd1[0],&prekiu_sk,sizeof(prekiu_sk));
write(fd1[1],&prekiu_sk,sizeof(prekiu_sk));
//prekiu_sk=prekiu_sk-*fd1;
printf("\n parent prekiu_sk: %d parent fd: %d \n", prekiu_sk, *fd1);
close(new_fd);
}
return 0;
}
答案 0 :(得分：1)
我怀疑你是按照使用管道的方式进行序列化的。即使我错了，看到父母和孩子同时对管道进行读写操作都表明存在问题。在您调用fork之后，父级和子级用于从管道中读取，这可能不是您想要的。
如果您确实想要在两个方向传递信息，请创建两个管道（一个用于父级＆gt;子流量，另一个用于子级 - >父级流量）。在fork（）之后，两个进程应该立即关闭它们没有使用的管道的末端，这将有助于你保持管道直接做什么。
如果您将此作为学习练习，您可以考虑其他几种方法：
只是一些想法让你去...