支持百万并发的服务器测试

支持百万并发和实现百万并发不是一个意思，能支持是实现的前提，本篇带你在配置较差的情况下，实现一个支持百万并发的服务器连接测试。

原理：基于epoll的Reactor模式。绝大多数的开源服务器框架，底层都是使用的epoll，Reactor是一种高效事件处理模式。

实验条件：准备四台虚拟机，一台当作服务器使用，另外三台当作客户端不断请求连接。如果你的实验环境和我一样，本机配置较差，可以只用两台虚拟机，一台做服务器，一台做客户机，客户机只需达到340000的连接，即可表明，三台客户机就可以达到上百万的并发连接。

在开始之前，我们先了解一下socket
socket的英文名是插座的意思，它是客户端和服务器建立通信连接的唯一标识，为何说它唯一，因为它是由五元组(源端口，目的端口，源ip，目的ip，通信协议)构成的，我们要知道，目的端口，源ip和目的ip都是确定的，这里唯一可以改变的就是源端口，我们都知道总的端口号也就是65535个，而且在一个进程中，默认单个进程能使用的端口号大概是28000(可以自己设置，但并没有解决实际问题)，所以就目前的情况来看单个端口是不行的。
实验过程中会遇到的问题：
1.一个进程的默认支持打开文件数为1024，有的是65535，但这显然是不够的，可以通过ulimit -a 来看到，我们可以看到表示最大文件描述符打开数的对应条目是 -n ，我们可以通过ulimit -n 数字 来修改最大打开文件描述符数量，其他数值同理。
这里我们先修改成ulimit -n 1024576，足够一百万使用了。
当然这种方式修改后重启后就没有了
可以在 /etc/sysctl.conf 下添加如下对fs.file-max值得修改，再往下一行表示得是tcp协议栈占用内存大小的现在，最后两行表示的是套接字发送和接收缓冲区的大小，可以看出每项都对应3个值，中间表示默认值，左边是最小值，右边是最大值。

2.若只使用一个端口，那么最大连接数目在28000左右，当然我们可以自己设置，但意义不大，没有解决实际问题，这里我们可以使用监听多个端口的方式，当然，在实际开发中，我们不会使用监听多端口的方式，而是使用多进程，这里有朋友可能要问，为什么是多进程而不是多线程，因为多线程的本质是同一个进程，没有扩大可打开的文件描述符数量，而每个进程拥有它独立的文件系统空间，所以我们需要使用多进程。
3. 客户端在连接进行到65535左右的时候还会出现问题，这里是由于，客户端本身对于一个进程的connect连接数量有限制，当到达一定的限制后，就无法发送出connect连接的消息，这里我们需要在 /etc/sysctl.conf 下添加如下内容来接触限制。
到此为止就可以完成测试了，需要注意的一点是做服务器的那台虚拟机，内存必须设置的大一点，因为每一个socket都含有发送和接收缓冲区，它们占用一定的内存空间，上百万的连接，自然要耗费不少空间，如果使用两台虚拟机进行测试，建议服务器端内存设置在8个G。当然，我们可以通过setsockopt这个函数设置socket的接受和发送缓冲区的大小，越小，同一内存大小的机器上就可以接受更多的连接。

单台客户机测试效果：
达到了340000万的连接数，没截图，这里是断开连接时的效果，可以看到fd数量在30多万。

若在自行测试的过程中遇到任何问题， 欢迎评论区留言。

服务器端代码：
有两版，这一版是单线程的，下面会给出一般使用了池的代码提高效率

#include 
#include 
#include 

#include 
#include 
#include 
#include 

#include 
#include 

#define BUFFER_LENGTH		1024
#define LISTEN_PORT 		100

struct sockitem { //
	int sockfd;
	int (*callback)(int fd, int events, void *arg);

	char recvbuffer[BUFFER_LENGTH]; //
	char sendbuffer[BUFFER_LENGTH];

	int rlength;
	int slength;
};

// mainloop / eventloop --> epoll -->  
struct reactor {

	int epfd;
	struct epoll_event events[512];
	
	

};


struct reactor *eventloop = NULL;


int recv_cb(int fd, int events, void *arg);


int send_cb(int fd, int events, void *arg) {

	struct sockitem *si = (struct sockitem*)arg;

	send(fd, si->sendbuffer, si->slength, 0); //

	struct epoll_event ev;
	ev.events = EPOLLIN | EPOLLET;
	//ev.data.fd = clientfd;
	si->sockfd = fd;
	si->callback = recv_cb;
	ev.data.ptr = si;

	epoll_ctl(eventloop->epfd, EPOLL_CTL_MOD, fd, &ev);

}

//  ./epoll 8080

int recv_cb(int fd, int events, void *arg) {

	//int clientfd = events[i].data.fd;
	struct sockitem *si = (struct sockitem*)arg;
	struct epoll_event ev;

	//char buffer[1024] = {0};
	int ret = recv(fd, si->recvbuffer, BUFFER_LENGTH, 0);
	if (ret < 0) {

		if (errno == EAGAIN || errno == EWOULDBLOCK) { //
			return -1;
		} else {
			
		}

		

		ev.events = EPOLLIN;
		//ev.data.fd = fd;
		epoll_ctl(eventloop->epfd, EPOLL_CTL_DEL, fd, &ev);

		close(fd);

		free(si);
		

	} else if (ret == 0) { //

		// 
		printf("disconnect %d\n", fd);

		ev.events = EPOLLIN;
		//ev.data.fd = fd;
		epoll_ctl(eventloop->epfd, EPOLL_CTL_DEL, fd, &ev);

		close(fd);

		free(si);
		
	} else {

		printf("Recv: %s, %d Bytes\n", si->recvbuffer, ret);

		si->rlength = ret;
		memcpy(si->sendbuffer, si->recvbuffer, si->rlength);
		si->slength = si->rlength;

		struct epoll_event ev;
		ev.events = EPOLLOUT | EPOLLET;
		//ev.data.fd = clientfd;
		si->sockfd = fd;
		si->callback = send_cb;
		ev.data.ptr = si;

		epoll_ctl(eventloop->epfd, EPOLL_CTL_MOD, fd, &ev);

	}

}


int accept_cb(int fd, int events, void *arg) {

	struct sockaddr_in client_addr;
	memset(&client_addr, 0, sizeof(struct sockaddr_in));
	socklen_t client_len = sizeof(client_addr);
	
	int clientfd = accept(fd, (struct sockaddr*)&client_addr, &client_len);
	if (clientfd <= 0) return -1;

	char str[INET_ADDRSTRLEN] = {0};
	printf("recv from %s at port %d\n", inet_ntop(AF_INET, &client_addr.sin_addr, str, sizeof(str)),
		ntohs(client_addr.sin_port));

	struct epoll_event ev;
	ev.events = EPOLLIN | EPOLLET;
	//ev.data.fd = clientfd;

	struct sockitem *si = (struct sockitem*)malloc(sizeof(struct sockitem));
	si->sockfd = clientfd;
	si->callback = recv_cb;
	ev.data.ptr = si;
	
	epoll_ctl(eventloop->epfd, EPOLL_CTL_ADD, clientfd, &ev);
	
	return clientfd;
}

int init_sock(short port) {
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd < 0) {
		return -1;
	}

	struct sockaddr_in addr;
	memset(&addr, 0, sizeof(struct sockaddr_in));

	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);
	addr.sin_addr.s_addr = inet_addr("192.168.5.128");
	//addr.sin_addr.s_addr = INADDR_ANY;

	if (bind(sockfd, (struct sockaddr*)&addr, sizeof(struct sockaddr_in)) < 0) {
		return -2;
	}

	if (listen(sockfd, 5) < 0) {
		return -3;
	}
	printf("port:%d\n", port);
	return sockfd;
}
int main(int argc, char *argv[]) {

	if (argc < 2) {
		return -1;
	}

	eventloop = (struct reactor*)malloc(sizeof(struct reactor));
	// epoll opera

	eventloop->epfd = epoll_create(1);
	int port = atoi(argv[1]);

	for(int i = 0; i < LISTEN_PORT; i++) {
		int sockfd = init_sock(port + i);
		struct epoll_event ev;
		ev.events = EPOLLIN;
		
		struct sockitem *si = (struct sockitem*)malloc(sizeof(struct sockitem));
		si->sockfd = sockfd;
		si->callback = accept_cb;
		ev.data.ptr = si;
	
	epoll_ctl(eventloop->epfd, EPOLL_CTL_ADD, sockfd, &ev);
	}

	

	
	
	

	while (1) {

		int nready = epoll_wait(eventloop->epfd, eventloop->events, 512, -1);
		if (nready < -1) {
			break;
		}

		int i = 0;
		for (i = 0;i < nready;i ++) {



			if (eventloop->events[i].events & EPOLLIN) {
				//printf("sockitem\n");
				struct sockitem *si = (struct sockitem*)eventloop->events[i].data.ptr;
				si->callback(si->sockfd, eventloop->events[i].events, si);

			}

			if (eventloop->events[i].events & EPOLLOUT) {

				struct sockitem *si = (struct sockitem*)eventloop->events[i].data.ptr;
				si->callback(si->sockfd, eventloop->events[i].events, si);

			}
		}

	}

}

服务器端代码（使用池）：建议使用

#include 
#include 
#include 
#include 
#include 
#include 

#include 
#include 
#include 


#define BUFFER_LENGTH		1024
#define MAX_EPOLL_EVENTS	1024*1024 //connection 
#define MAX_EPOLL_ITEM		102400 //con
#define SERVER_PORT			8888

#define LISTEN_PORT_COUNT	100

typedef int NCALLBACK(int ,int, void*);

struct ntyevent {
	int fd;
	int events;
	void *arg;
	int (*callback)(int fd, int events, void *arg);
	
	int status;
	char buffer[BUFFER_LENGTH];
	int length;
	long last_active;
};



struct ntyreactor {
	int epfd;
	struct ntyevent *events; // 1024 * 1024
};


int recv_cb(int fd, int events, void *arg);
int send_cb(int fd, int events, void *arg);


void nty_event_set(struct ntyevent *ev, int fd, NCALLBACK callback, void *arg) {

	ev->fd = fd;
	ev->callback = callback;
	ev->events = 0;
	ev->arg = arg;
	ev->last_active = time(NULL);

	return ;
	
}


int nty_event_add(int epfd, int events, struct ntyevent *ev) {

	struct epoll_event ep_ev = {0, {0}};
	ep_ev.data.ptr = ev;
	ep_ev.events = ev->events = events;

	int op;
	if (ev->status == 1) {
		op = EPOLL_CTL_MOD;
	} else {
		op = EPOLL_CTL_ADD;
		ev->status = 1;
	}

	if (epoll_ctl(epfd, op, ev->fd, &ep_ev) < 0) {
		printf("event add failed [fd=%d], events[%d]\n", ev->fd, events);
		return -1;
	}

	return 0;
}

int nty_event_del(int epfd, struct ntyevent *ev) {

	struct epoll_event ep_ev = {0, {0}};

	if (ev->status != 1) {
		return -1;
	}

	ep_ev.data.ptr = ev;
	ev->status = 0;
	epoll_ctl(epfd, EPOLL_CTL_DEL, ev->fd, &ep_ev);

	return 0;
}

int recv_cb(int fd, int events, void *arg) {

	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	struct ntyevent *ev = reactor->events+fd;

	int len = recv(fd, ev->buffer, BUFFER_LENGTH, 0);
	nty_event_del(reactor->epfd, ev);

	if (len > 0) {
		
		ev->length = len;
		ev->buffer[len] = '\0';

		printf("C[%d]:%s\n", fd, ev->buffer);

		nty_event_set(ev, fd, send_cb, reactor);
		nty_event_add(reactor->epfd, EPOLLOUT, ev);
		
		
	} else if (len == 0) {

		close(ev->fd);
		printf("[fd=%d] pos[%ld], closed\n", fd, ev-reactor->events);
		 
	} else {

		close(ev->fd);
		printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno));
		
	}

	return len;
}


int send_cb(int fd, int events, void *arg) {

	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	struct ntyevent *ev = reactor->events+fd;

	int len = send(fd, ev->buffer, ev->length, 0);
	if (len > 0) {
		printf("send[fd=%d], [%d]%s\n", fd, len, ev->buffer);

		nty_event_del(reactor->epfd, ev);
		
		nty_event_set(ev, fd, recv_cb, reactor);
		nty_event_add(reactor->epfd, EPOLLIN, ev);
		
	} else {

		close(ev->fd);

		nty_event_del(reactor->epfd, ev);
		printf("send[fd=%d] error %s\n", fd, strerror(errno));

	}

	return len;
}

int accept_cb(int fd, int events, void *arg) {

	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	if (reactor == NULL) return -1;

	struct sockaddr_in client_addr;
	socklen_t len = sizeof(client_addr);

	int clientfd;

	if ((clientfd = accept(fd, (struct sockaddr*)&client_addr, &len)) == -1) {
		if (errno != EAGAIN && errno != EINTR) {
			
		}
		printf("accept: %s\n", strerror(errno));
		return -1;
	}

	int i = 0;
	do {
#if 0
		for (i = 0;i < MAX_EPOLL_EVENTS;i ++) {
			if (reactor->events[i].status == 0) {
				break;
			}
		}
		if (i == MAX_EPOLL_EVENTS) {
			printf("%s: max connect limit[%d]\n", __func__, MAX_EPOLL_EVENTS);
			break;
		}
#endif
		int flag = 0;
		if ((flag = fcntl(clientfd, F_SETFL, O_NONBLOCK)) < 0) {
			printf("%s: fcntl nonblocking failed, %d\n", __func__, MAX_EPOLL_EVENTS);
			break;
		}

		nty_event_set(&reactor->events[clientfd], clientfd, recv_cb, reactor);
		nty_event_add(reactor->epfd, EPOLLIN, &reactor->events[clientfd]);

	} while (0);

	printf("new connect [%s:%d][time:%ld], pos[%d]\n", 
		inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), reactor->events[i].last_active, i);

	return 0;

}

int init_sock(short port) {

	int fd = socket(AF_INET, SOCK_STREAM, 0);
	fcntl(fd, F_SETFL, O_NONBLOCK);

	struct sockaddr_in server_addr;
	memset(&server_addr, 0, sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	server_addr.sin_port = htons(port);

	bind(fd, (struct sockaddr*)&server_addr, sizeof(server_addr));

	if (listen(fd, 20) < 0) {
		printf("listen failed : %s\n", strerror(errno));
	}

	printf("listen port : %d\n", port);

	return fd;
}


int ntyreactor_init(struct ntyreactor *reactor) {

	if (reactor == NULL) return -1;
	memset(reactor, 0, sizeof(struct ntyreactor));

	reactor->epfd = epoll_create(1);
	if (reactor->epfd <= 0) {
		printf("create epfd in %s err %s\n", __func__, strerror(errno));
		return -2;
	}

	reactor->events = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
	if (reactor->events == NULL) {
		printf("create epfd in %s err %s\n", __func__, strerror(errno));
		close(reactor->epfd);
		return -3;
	}
}

int ntyreactor_destory(struct ntyreactor *reactor) {

	close(reactor->epfd);
	free(reactor->events);

}



int ntyreactor_addlistener(struct ntyreactor *reactor, int sockfd, NCALLBACK *acceptor) {

	if (reactor == NULL) return -1;
	if (reactor->events == NULL) return -1;

	nty_event_set(&reactor->events[sockfd], sockfd, acceptor, reactor);
	nty_event_add(reactor->epfd, EPOLLIN, &reactor->events[sockfd]);

	return 0;
}



int ntyreactor_run(struct ntyreactor *reactor) {
	if (reactor == NULL) return -1;
	if (reactor->epfd < 0) return -1;
	if (reactor->events == NULL) return -1;
	
	struct epoll_event events[MAX_EPOLL_ITEM];
	
	int checkpos = 0, i;

	while (1) {
#if 0
		long now = time(NULL);
		for (i = 0;i < 100;i ++, checkpos ++) {
			if (checkpos == MAX_EPOLL_EVENTS) {
				checkpos = 0;
			}

			if (reactor->events[checkpos].status != 1) {
				continue;
			}

			long duration = now - reactor->events[checkpos].last_active;

			if (duration >= 60) {
				close(reactor->events[checkpos].fd);
				printf("[fd=%d] timeout\n", reactor->events[checkpos].fd);
				nty_event_del(reactor->epfd, &reactor->events[checkpos]);
			}
		}
#endif

		int nready = epoll_wait(reactor->epfd, events, MAX_EPOLL_ITEM, 1000);
		if (nready < 0) {
			printf("epoll_wait error, exit\n");
			continue;
		}

		for (i = 0;i < nready;i ++) {

			struct ntyevent *ev = (struct ntyevent*)events[i].data.ptr;

			if ((events[i].events & EPOLLIN) && (ev->events & EPOLLIN)) {
				ev->callback(ev->fd, events[i].events, ev->arg);
			}
			if ((events[i].events & EPOLLOUT) && (ev->events & EPOLLOUT)) {
				ev->callback(ev->fd, events[i].events, ev->arg);
			}
			
		}

	}
}

int main(int argc, char *argv[]) {

	unsigned short port = SERVER_PORT;
	if (argc == 2) {
		port = atoi(argv[1]);
	}
	struct ntyreactor *reactor = (struct ntyreactor*)malloc(sizeof(struct ntyreactor));
	ntyreactor_init(reactor);
	

	int listenfd[LISTEN_PORT_COUNT] = {0};
	int i = 0;

	for (i = 0;i < LISTEN_PORT_COUNT;i ++) {
		listenfd[i] = init_sock(port+i);
		ntyreactor_addlistener(reactor, listenfd[i], accept_cb);
	}
	
	ntyreactor_run(reactor);

	ntyreactor_destory(reactor);

	for (i = 0;i < LISTEN_PORT_COUNT;i ++) {
		close(listenfd[i]);
	}
	

	return 0;
}

客户端代码

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 


#define MAX_BUFFER		128
#define MAX_EPOLLSIZE	(384*1024)
#define MAX_PORT		100

#define TIME_SUB_MS(tv1, tv2)  ((tv1.tv_sec - tv2.tv_sec) * 1000 + (tv1.tv_usec - tv2.tv_usec) / 1000)

int isContinue = 0;

static int ntySetNonblock(int fd) {
	int flags;

	flags = fcntl(fd, F_GETFL, 0);
	if (flags < 0) return flags;
	flags |= O_NONBLOCK;
	if (fcntl(fd, F_SETFL, flags) < 0) return -1;
	return 0;
}

static int ntySetReUseAddr(int fd) {
	int reuse = 1;
	return setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *)&reuse, sizeof(reuse));
}



int main(int argc, char **argv) {
	if (argc <= 2) {
		printf("Usage: %s ip port\n", argv[0]);
		exit(0);
	}

	const char *ip = argv[1];
	int port = atoi(argv[2]);
	int connections = 0;
	char buffer[128] = {0};
	int i = 0, index = 0;

	struct epoll_event events[MAX_EPOLLSIZE];
	
	int epoll_fd = epoll_create(MAX_EPOLLSIZE);
	
	strcpy(buffer, " Data From MulClient\n");
		
	struct sockaddr_in addr;
	memset(&addr, 0, sizeof(struct sockaddr_in));
	
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = inet_addr(ip);

	struct timeval tv_begin;
	gettimeofday(&tv_begin, NULL);

	while (1) {
		if (++index >= MAX_PORT) index = 0;
		
		struct epoll_event ev;
		int sockfd = 0;

		if (connections < 340000 && !isContinue) {
			sockfd = socket(AF_INET, SOCK_STREAM, 0);
			if (sockfd == -1) {
				perror("socket");
				goto err;
			}

			//ntySetReUseAddr(sockfd);
			addr.sin_port = htons(port+index);

			if (connect(sockfd, (struct sockaddr*)&addr, sizeof(struct sockaddr_in)) < 0) {
				perror("connect");
				goto err;
			}
			ntySetNonblock(sockfd);
			ntySetReUseAddr(sockfd);

			sprintf(buffer, "Hello Server: client --> %d\n", connections);
			send(sockfd, buffer, strlen(buffer), 0);

			ev.data.fd = sockfd;
			ev.events = EPOLLIN | EPOLLOUT;
			epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sockfd, &ev);
		
			connections ++;
		}
		//connections ++;
		if (connections % 1000 == 999 || connections >= 340000) {
			struct timeval tv_cur;
			memcpy(&tv_cur, &tv_begin, sizeof(struct timeval));
			
			gettimeofday(&tv_begin, NULL);

			int time_used = TIME_SUB_MS(tv_begin, tv_cur);
			printf("connections: %d, sockfd:%d, time_used:%d\n", connections, sockfd, time_used);

			int nfds = epoll_wait(epoll_fd, events, connections, 100);
			for (i = 0;i < nfds;i ++) {
				int clientfd = events[i].data.fd;

				if (events[i].events & EPOLLOUT) {
					sprintf(buffer, "data from %d\n", clientfd);
					send(sockfd, buffer, strlen(buffer), 0);
				} else if (events[i].events & EPOLLIN) {
					char rBuffer[MAX_BUFFER] = {0};				
					ssize_t length = recv(sockfd, rBuffer, MAX_BUFFER, 0);
					if (length > 0) {
						printf(" RecvBuffer:%s\n", rBuffer);

						if (!strcmp(rBuffer, "quit")) {
							isContinue = 0;
						}
						
					} else if (length == 0) {
						printf(" Disconnect clientfd:%d\n", clientfd);
						connections --;
						close(clientfd);
					} else {
						if (errno == EINTR) continue;

						printf(" Error clientfd:%d, errno:%d\n", clientfd, errno);
						close(clientfd);
					}
				} else {
					printf(" clientfd:%d, errno:%d\n", clientfd, errno);
					close(clientfd);
				}
			}
		}

		usleep(1 * 1000);
	}

	return 0;

err:
	printf("error : %s\n", strerror(errno));
	return 0;
	
}