c1000k，单机百万并发测试

使用epoll实现的reactor服务端，开启一个进程多个端口，然后使用多个客户端 ip 多端口来连接

​ 1、在16g内存的笔记本上

​ 2、用四台虚拟机（一台服务器 三台客户端）

​ 3、使用epoll写的reactor反应堆服务端，源码在最下面

​ 4、多线程的客户端，源码在最下面

​ 并发：一个服务器能够同时承载客户端的数量

​ 服务器能同时建立连接的数量 是并发的基础

​ 承载 100w 在200ms内返回

​ 这里回声服务器 没有下列多余影响

​ 1、数据库 2、网络带宽 3、内存操作 4、日志

一、一个连接的定义

1.1 服务器理论最大并发数

​ 一个连接包含五元组，源ip（sip）、目的ip（dip）源端口（sport）、目的端、（dport） 协议

2 的 32 次方（源ip数）× 2的 16 次方（源port数）× 2 的 32 次方（目的ip数）× 2的 16 次方（目的port数）大约等于四百多亿亿亿

（不过每条连接都会消耗服内存，实践中绝不可能达到这个理论数字。）

1.2 测试实验配置

这里使用一个服务端ip * 100服务端端口 * 60000客户端端口 * 3 个客户端 理论上可以达到200w连接 奈何笔记本内存不够

sip 多个客户端 这里采用三个虚拟机（三个ip）

dip 服务器IP只有一个 使用一个虚拟机（一个ip）

sport 客户端数量 使用60000个端口

dport 服务的端口 使用100个端口

proto tcp 使用tcp连接

1.3 linux系统的连接相关默认配置

看看ubuntu20.04的默认配置

root@luo:~# ulimit -n
1024
root@luo:~# sysctl -a |grep mem
...
net.ipv4.tcp_mem = 92880	123843	185760 # 92880* 4k 300m 500m 700m 当协议栈占用空间500m时优化 大于700m时不再分配
net.ipv4.tcp_rmem = 4096	131072	6291456
net.ipv4.tcp_wmem = 4096	16384	4194304
...
net.ipv4.ip_local_port_range = 32768	60999
fs.file-max = 9223372036854775807
net.nf_conntrack_max = 65536

1.4下面解释配置的作用

1、net.ipv4.tcp_mem TCP使用了内存页面数

​ net.ipv4.tcp_rmem 为TCP socket预留用于接收缓冲的内存 ​ net.ipv4.tcp_wmem 为TCP socket预留用于发送缓冲的内存

​ tcp_wmem tcp_rmem服务器传输大文件就调大 传输字符 调小（但可能ssh 都会很慢） 一个fd就是tcp_wmem tcp_rmem所占用空间 使用更少的内存

2、ulimit -n 和 net.nf_conntrack_max fd 限制 ulimit 限制fd 数量

​ 默认单个进程打开的fd为1000多个 可以修改ulimit -n 1048576（临时修改） 或 /etc/security/limits.conf（永久修改）

accept: Too many open files

3、net.ipv4.ip_local_port_range 默认用户只能用30000以上的端口建立连接 要自己改

​ 建立连接时 服务端端口从三万多开始挨个遍历 找到一个没有被占用的

connections: 27999, sockfd:28002, time_used:3193
connect: Cannot assign requested address
error : Cannot assign requested address

4、net.nf_conntrack_max 服务端建立连接的syn连接数

​ iptables基于netfilter的应用程序 iptables会调用netfilrer的接口

​ 报文sk_buff从网卡上到达协议栈时会经过netfilter

conntion timeout

二、实验开始

2.1 使用sysctl临时修改配置（重启后失效）

#send buffer 服务器传输大文件就调大  传输字符 调小（但可能ssh 都会很慢） 一个fd就是tcp_wmem  tcp_rmem所占用空间 使用更少的内存
sysctl -w net.ipv4.tcp_wmem="2048 2048 4096"
sysctl -w net.ipv4.tcp_rmem="2048 2048 4096"

sysctl -w net.ipv4.tcp_mem="262144 524288 786432" # 262144*4k 1g 2g 3g 当协议栈占用空间2g时优化 大于3g时不再分配
sysctl -w net.ipv4.ip_local_port_range="1025 64000"
ulimit -n 1048576
modprobe ip_conntrack
sysctl -w net.nf_conntrack_max=1048576

2.2 编译最下方源码 开启c/s回声服务器看效果

send[fd=980328], [32]Hello Server: client --> 329478

1、服务端启动后看一下内存

root@luo:~# free
              total        used        free      shared  buff/cache   available
Mem:        8117280     2376860     5343540        1620      396880     5485128
Swap:       4001788           0     4001788

2、服务端维持980000连接时的内存

root@luo:~# free
              total        used        free      shared  buff/cache   available
Mem:        8117280     6973192      103992           0     1040096      913852
Swap:       4001788     1090996     2910792

3、计算单条连接消耗内存

6973192 - 2376860 = 4596332 ÷ 800000= 4.69

由于笔记本开了4台虚拟机一起跑 连接总是到90多万的时候虚拟机崩溃 最多980000

平均计算一个连接4k左右

三、测试中的一些问题以及优化方向

文件描述符fd不够

​ 端口数量不够

​ accept 全连接队列满了

​ 客户端超时 服务端不会ack 连接队列满了？

半连接全连接 连接队列的问题 满了后需要排队

会导致网络抖动 accept线程池竞争 多线程accept

多线程的网络模型 redis memcached nginx

​ 1、accept与recv/send的fd分开

​ 2、多线程accept

​ nginx memcached多进程更符合业务处理 固定多线程接入 多线程业务处理

​

源码

reactor.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <arpa/inet.h>

#include <fcntl.h>
#include <unistd.h>
#include <errno.h>


#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
        //                                  一次能从就绪队列带出数量 event长度 时间
        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;
}

mul_port_client_epoll.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <errno.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <fcntl.h>


#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 < 500000 && !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;
    
}