学步园

最近在发现select（fd + 1, &readfd, &writefd, &expfd, NULL）; 此时select已经进入等待状态， 然而 fd 被其他线程关闭时， select并不能及时发现，而依旧是处于等待中。

#include <stdio.h><br /> #include <stdlib.h><br /> #include <unistd.h><br /> #include <errno.h><br /> #include <string.h><br /> #include <sys/types.h><br /> #include <sys/socket.h><br /> #include <netinet/in.h><br /> #include <arpa/inet.h><br /> #include <pthread.h><br /> #define MYPORT 1234 // the port users will be connecting to<br /> #define BACKLOG 5 // how many pending connections queue will hold<br /> #define BUF_SIZE 200<br /> int fd_A[BACKLOG]; // accepted connection fd<br /> int conn_amount; // current connection amount<br /> void showclient()<br /> {<br /> int i;<br /> printf("client amount: %d/n", conn_amount);<br /> for (i = 0; i < BACKLOG; i++) {<br /> printf("[%d]:%d ", i, fd_A[i]);<br /> }<br /> printf("/n/n");<br /> }<br /> void* _ThreadEntry(void * pParam)<br /> {<br /> int *sock_fd = (int *)pParam;<br /> fd_set readfds;<br /> fd_set errfds;</p> <p> FD_ZERO(&readfds);<br /> FD_ZERO(&errfds);<br /> FD_SET(*sock_fd, &readfds);<br /> FD_SET(*sock_fd, &errfds);</p> <p> printf ("go to select/n");<br /> int ret = select(*sock_fd + 1, NULL, NULL, &errfds, NULL);<br /> printf ("select end ret=%d/n", ret);<br /> printf ("thread end/n");<br /> }<br /> int main(void)<br /> {<br /> int sock_fd, new_fd; // listen on sock_fd, new connection on new_fd<br /> struct sockaddr_in server_addr; // server address information<br /> struct sockaddr_in client_addr; // connector's address information<br /> socklen_t sin_size;<br /> int yes = 1;<br /> char buf[BUF_SIZE];<br /> int ret;<br /> int i;<br /> if ((sock_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {<br /> perror("socket");<br /> exit(1);<br /> }<br /> pthread_t tid;</p> <p> pthread_create(&tid, NULL, _ThreadEntry, &sock_fd);</p> <p> sleep(1);</p> <p> printf("close sock/n");<br /> close(sock_fd);</p> <p> getchar();<br /> getchar();<br /> exit(0);<br /> } 

运行 结果 ：

[root@localhost hellolinux]# ./hello

go to select

close sock