为什么当连接超过 3800 时 epoll 变慢

如何解决为什么当连接超过 3800 时 epoll 变慢

我正在用 epoll 做一个连接测试，我发现如果我的客户端连接大约 3800，epoll 变得很慢，而且它每秒只接受一个连接，我修改了 /etc/sysctl.conf 中的一些系统参数,但它不起作用;

我的操作系统是 CentOS 7.6

#include <cstdio>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <iostream>


#define SERVER_WAIT_COUNT 10000
#define SERVER_LISTEN_BACKLOG 1000
int main()
{
    int sock_fd = socket(AF_INET,SOCK_STREAM,0);
    
    struct sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(12378);
    // inet_aton(addr,&(serverAddr.sin_addr));

    serverAddr.sin_addr.s_addr = INADDR_ANY;
    int ret = bind(sock_fd,(sockaddr*)&serverAddr,sizeof(sockaddr));

    ret = listen(sock_fd,20);

    struct epoll_event ev,events[SERVER_WAIT_COUNT];
    ev.data.fd = sock_fd;
    ev.events = EPOLLET | EPOLLIN;

    int listenEpollFD = epoll_create(SERVER_LISTEN_BACKLOG);

    ret = epoll_ctl(listenEpollFD,EPOLL_CTL_ADD,sock_fd,&ev);
    printf("EPOLL_CLI_ADD: %d",EPOLL_CTL_ADD);
    static int clientCount = 0;
    while (true) {
        int eventCount = epoll_wait(listenEpollFD,events,SERVER_WAIT_COUNT,-1);
        if (eventCount == -1) {            
            continue;            
        }
        for (int i = 0; i < eventCount; i++) {
            if (events[i].data.fd == sock_fd) {
                struct sockaddr_in clientAddr;
                socklen_t client;
                accept(sock_fd,(sockaddr*)&clientAddr,&client);
                clientCount++;
                printf("accept a connection,current count: %d",clientCount);
                std::cout << "current count:" << clientCount << std::endl;
            }
        }
    }
    printf("hello from epollTest!\n");
    return 0;
}