2高并发服务器：多线程服务器
1多線程并發服務器
在使用線程模型開發服務器時需要考慮以下問題：
A調整進程最大文件描述符上限
B線程如有共享數據，考慮線程同步
C服務于客戶端線程退出時，退出處理。（退出值，分離態）
D系統負載，隨著連接客戶端增加，導致其它線程不能及時得到CPU
2.案例說明
server.c,代碼如下：
| /* server.c */ #include <stdio.h> #include <string.h> #include <netinet/in.h> #include <arpa/inet.h> #include <pthread.h> #include "wrap.h" #define MAXLINE 80 #define SERV_PORT 8000 ? struct s_info { struct sockaddr_in cliaddr; int connfd; }; ? void *do_work(void *arg) { int n,i; struct s_info *ts = (struct s_info*)arg; char buf[MAXLINE]; char str[INET_ADDRSTRLEN]; /*可以在創建線程前設置線程創建屬性,設為分離態,哪種效率高內？?答：線程前設置線程屬性*/ pthread_detach(pthread_self()); while (1) { n = Read(ts->connfd, buf, MAXLINE); if (n == 0) { printf("the other side has been closed.\n"); break; } printf("received from %s at PORT %d\n", inet_ntop(AF_INET, &(*ts).cliaddr.sin_addr, str, sizeof(str)), ntohs((*ts).cliaddr.sin_port)); for (i = 0; i < n; i++) { buf[i] = toupper(buf[i]); ???????} Write(ts->connfd, buf, n); } Close(ts->connfd); } ? int main(void) { struct sockaddr_in servaddr, cliaddr; socklen_t cliaddr_len; int listenfd, connfd; int i = 0; pthread_t tid; struct s_info ts[383]; 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); ts[i].cliaddr = cliaddr; ts[i].connfd = connfd; /*達到線程最大數時，pthread_create出錯處理,增加服務器穩定性*/ pthread_create(&tid, NULL, do_work, (void*)&ts[i]); i++; } ?Close(listenfd); return 0; } |
client.c
| /* client.c */ #include <stdio.h> #include <string.h> #include <unistd.h> #include <netinet/in.h> #include "wrap.h" #define MAXLINE 80 #define SERV_PORT 8000 int main(int argc, char *argv[]) { struct sockaddr_in servaddr; char buf[MAXLINE]; int sockfd, n; 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); servaddr.sin_port = htons(SERV_PORT); Connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)); while (fgets(buf, MAXLINE, stdin) != NULL) { Write(sockfd, buf, strlen(buf)); n = Read(sockfd, buf, MAXLINE); if (n == 0) printf("the other side has been closed.\n"); else Write(STDOUT_FILENO, buf, n); } Close(sockfd); return 0; } |
wrap.h
| #ifndef __WRAP_H_ #define __WRAP_H_ ? void perr_exit(const char *s); int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr); void Bind(int fd, const struct sockaddr *sa, socklen_t salen); void Connect(int fd, const struct sockaddr *sa, socklen_t salen); void Listen(int fd, int backlog); int Socket(int family, int type, int protocol); ssize_t Read(int fd, void *ptr, size_t nbytes); ssize_t Write(int fd, const void *ptr, size_t nbytes); void Close(int fd); ssize_t Readn(int fd, void *vptr, size_t n); ssize_t Writen(int fd, const void *vptr, size_t n); static ssize_t my_read(int fd, char *ptr); ssize_t Readline(int fd, void *vptr, size_t maxlen); ? #endif |
wrap.c
| #include <stdlib.h> #include <errno.h> #include <sys/socket.h> ? void perr_exit(const char *s) { ????????perror(s); ????????exit(1); } ? int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr) { ????????int n; ? again: ????????if ( (n = accept(fd, sa, salenptr)) < 0) { ??????????????????if ((errno == ECONNABORTED) || (errno == EINTR)) ???????????????????????????goto again; ??????????????????else ???????????????????????????perr_exit("accept error"); ????????} ????????return n; } ? void Bind(int fd, const struct sockaddr *sa, socklen_t salen) { ????????if (bind(fd, sa, salen) < 0) ??????????????????perr_exit("bind error"); } ? void Connect(int fd, const struct sockaddr *sa, socklen_t salen) { ????????if (connect(fd, sa, salen) < 0) ??????????????????perr_exit("connect error"); } ? void Listen(int fd, int backlog) { ????????if (listen(fd, backlog) < 0) ??????????????????perr_exit("listen error"); } ? int Socket(int family, int type, int protocol) { ????????int n; ? ????????if ( (n = socket(family, type, protocol)) < 0) ??????????????????perr_exit("socket error"); ????????return n; } ? ssize_t Read(int fd, void *ptr, size_t nbytes) { ????????ssize_t n; ? again: ????????if ( (n = read(fd, ptr, nbytes)) == -1) { ??????????????????if (errno == EINTR) ???????????????????????????goto again; ??????????????????else ???????????????????????????return -1; ????????} ????????return n; } ? ssize_t Write(int fd, const void *ptr, size_t nbytes) { ????????ssize_t n; ? again: ????????if ( (n = write(fd, ptr, nbytes)) == -1) { ??????????????????if (errno == EINTR) ???????????????????????????goto again; ??????????????????else ???????????????????????????return -1; ????????} ????????return n; } ? void Close(int fd) { ????????if (close(fd) == -1) ??????????????????perr_exit("close error"); } ssize_t Readn(int fd, void *vptr, size_t n) { ????????size_t?nleft; ????????ssize_t nread; ????????char??*ptr; ? ????????ptr = vptr; ????????nleft = n; ????????while (nleft > 0) { ??????????????????if ( (nread = read(fd, ptr, nleft)) < 0) { ???????????????????????????if (errno == EINTR) ????????????????????????????????????nread = 0; ???????????????????????????else ????????????????????????????????????return -1; ??????????????????} else if (nread == 0) ???????????????????????????break; ? ??????????????????nleft -= nread; ??????????????????ptr += nread; ????????} ????????return n - nleft; } ? ssize_t Writen(int fd, const void *vptr, size_t n) { ????????size_t nleft; ????????ssize_t nwritten; ????????const char *ptr; ? ????????ptr = vptr; ????????nleft = n; ????????while (nleft > 0) { ??????????????????if ( (nwritten = write(fd, ptr, nleft)) <= 0) { ???????????????????????????if (nwritten < 0 && errno == EINTR) ????????????????????????????????????nwritten = 0; ???????????????????????????else ????????????????????????????????????return -1; ??????????????????} ? ??????????????????nleft -= nwritten; ??????????????????ptr += nwritten; ????????} ????????return n; } static ssize_t my_read(int fd, char *ptr) { ????????static int read_cnt; ????????static char *read_ptr; ????????static char read_buf[100]; ? ????????if (read_cnt <= 0) { again: ??????????????????if ( (read_cnt = read(fd, read_buf, sizeof(read_buf))) < 0) { ???????????????????????????if (errno == EINTR) ????????????????????????????????????goto again; ???????????????????????????return -1; ??????????????????} else if (read_cnt == 0) ???????????????????????????return 0; ??????????????????read_ptr = read_buf; ????????} ????????read_cnt--; ????????*ptr = *read_ptr++; ????????return 1; } ? ssize_t Readline(int fd, void *vptr, size_t maxlen) { ????????ssize_t n, rc; ????????char???c, *ptr; ? ????????ptr = vptr; ????????for (n = 1; n < maxlen; n++) { ??????????????????if ( (rc = my_read(fd, &c)) == 1) { ???????????????????????????*ptr++ = c; ???????????????????????????if (c?== '\n') ????????????????????????????????????break; ??????????????????} else if (rc == 0) { ???????????????????????????*ptr = 0; ???????????????????????????return n - 1; ??????????????????} else { ???????????????????????????return -1; ???????} ????????}?????????????????? ????????*ptr?= 0; ????????return n; } |
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