尝试限制客户端 - 服务器c应用程序中的客户端连接数量。这就是我所拥有的,但它不起作用。 (甚至无法识别何时达到max_connections。我该如何解决这个问题?
int main(int argc, char *argv[])
{
//fill db
if (obtainDb() == false) {
printf("Database obtain error.\n");
exit(true);
}
//initialise variables
total_connections = 0;
/* generate the socket */
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(true);
}
/* generate the end point */
my_addr.sin_family = AF_INET; // host byte order
my_addr.sin_port = htons(MYPORT); // short, network byte order
my_addr.sin_addr.s_addr = INADDR_ANY; // auto-fill with my IP
/* bind the socket to the end point */
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) \
== -1) {
perror("bind");
exit(true);
}
/* start listnening */
if (listen(sockfd, BACKLOG) == -1) {
perror("listen");
exit(true);
}
printf("server starts listnening ...\n");
while(true){
sin_size = sizeof(struct sockaddr_in);
if (total_connections == max_connections) {
printf("Max Number of clients connected!\n");
while(total_connections == max_connections);
}
if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, \
&sin_size)) == -1) {
perror("accept");
continue;
}
total_connections++;
printf("server: got connection from %s\n", \
inet_ntoa(their_addr.sin_addr));
userInput();
while(waitpid(-1,NULL,WNOHANG)>0);
}
return false;
}
由于
编辑:UserInput():
void userInput(void) {
if (!fork()) { // this is the child process
while(true){
char buffer[MAXDATASIZE];
char res[MAXDATASIZE];
memset(buffer, '\0', MAXDATASIZE);
memset(res, '\0', sizeof(res));
if ((numbytes=recv(new_fd, buffer, sizeof(buffer), 0)) == -1) {
perror("recv");
exit(true);
}
if (numbytes == 0) {
printf("client left");
close(new_fd);
total_connections--;
exit(false);
}
buffer[numbytes] = '\0'; // add null terminator
printf("Request: %s\n",buffer);
search(buffer,res);
}
close(new_fd); // parent doesn't need this
exit(false);
}
close(new_fd);
}
答案 0 :(得分:2)
当fork
所有变量复制到新流程时。这意味着孩子们拥有自己的total_connections
副本。
您应该使用wait
来确定是否已退出任何子项,而不是使用变量。
答案 1 :(得分:1)
Forking创建了一个新的进程实例,这也意味着每个变量都被复制到新进程中。您的初始total_connections
实际上永远不会超过1。
C fork dealing with global variable
一个相对简单的选择是使用线程而不是同时处理多个客户端的进程。