环回多播WinSock的性能降低

问题描述

我正在将嵌入式分布式系统移植到Windows，我需要通过环回发送多播和单播数据包，我发现由于某些未知原因，发送多播所花的时间比发送单播所花费的时间多2倍。
我的环境非常简单，我赢了10台带有3个网卡的机器，出于应用目的，我仅使用一个分配了两个IP地址的NIC。为了测试，我编写了简单的客户端和服务器应用程序，客户端绑定到第一个IP地址（192.168.1.47），服务器绑定到第二个（192.168.1.46）。
客户端应用发送500个Ucast和500个Mcast数据包，并显示在sendto（）函数中花费的平均时间。 如果客户端和服务器是在两台单独的计算机上启动的，则两次的时间几乎相同，但是如果它们在同一台计算机上启动，则Mcast的时间要长2-3倍。
任何人遇到类似的问题或知道其原因是什么？我会提出任何建议，谢谢！

下面的代码：

#include <iostream>
#include <winsock2.h>
#include <WS2tcpip.h>
#include <chrono>
#include <vector>
#include <numeric>

#pragma comment(lib,"ws2_32.lib") //Winsock Library

void Send(SOCKET& socket,SOCKADDR_IN& sockAddr);

int main()
{
    // Params
    char localIp[] = "192.168.1.47";
    char dstMcastAddress[] = "239.4.5.6";
    char dstUcastAddress[] = "192.168.1.46";
    int port = 5120;


    //Initialize WinSock2
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2,2),&wsaData) != 0)
    {
        std::cout << "WSAStartup error\r\n";
        WSACleanup();
        return -1;
    }

    // Create socket
    SOCKET sendSocket = socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);
    if (sendSocket == INVALID_SOCKET)
    {
        int error = WSAGetLastError();
        std::cout << "Unable to open socket " << error << std::endl;
    }

    SOCKADDR_IN localAddress;
    localAddress.sin_family = AF_INET;
    inet_pton(AF_INET,localIp,&(localAddress.sin_addr));
    if (bind(sendSocket,(SOCKADDR*)&localAddress,sizeof(localAddress)) == SOCKET_ERROR)
    {
        std::cout << "Client: bind() Failed! Error: " << WSAGetLastError() << std::endl;
        closesocket(sendSocket);
        WSACleanup();
        return -1;

    }

    SOCKADDR_IN receiverUcast;
    receiverUcast.sin_family = AF_INET;
    receiverUcast.sin_port = htons(port);
    inet_pton(AF_INET,dstUcastAddress,&(receiverUcast.sin_addr));
    std::cout << "Ucast: ";
    Send(sendSocket,receiverUcast);

    SOCKADDR_IN receiverMcast;
    receiverMcast.sin_family = AF_INET;
    receiverMcast.sin_port = htons(port);
    inet_pton(AF_INET,dstMcastAddress,&(receiverMcast.sin_addr));
    std::cout << "Mcast: ";
    Send(sendSocket,receiverMcast);
}

void Send(SOCKET& socket,SOCKADDR_IN& sockAddr)
{
    char SendBuf[1000];
    std::vector<int> vec;
    int i = 0;

    while (i++ < 500)
    {
        snprintf(SendBuf,sizeof(SendBuf),"Udp client send %02d",i);

        auto start = std::chrono::system_clock::Now();
        int TotalByteSent = sendto(socket,SendBuf,strlen(SendBuf),(SOCKADDR*)&sockAddr,sizeof(sockAddr));
        auto end = std::chrono::system_clock::Now();

        if (TotalByteSent < 0)
        {
            std::cout << "Send error\r\n";
        }
        auto elapsed = std::chrono::duration_cast<std::chrono::microseconds>(end - start);
        vec.push_back(elapsed.count());
    }

    double average = std::accumulate(vec.begin(),vec.end(),0.0) / vec.size();
    std::cout << average << std::endl;
}

服务器：

#include <iostream>
#include <winsock2.h>
#include <WS2tcpip.h>
#include <chrono>
#include <vector>
#include <numeric>
#include <string_view>
#include <string>

#pragma comment(lib,"ws2_32.lib") //Winsock Library

int main()
{
    // Params
    char localIp[] = "192.168.1.46";
    char dstMcastAddress[] = "239.4.5.6";
    int port = 5120;

    char receiveBuffer[1000];

    /// Initialize WinSock2
    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2,&wsaData) != 0)
    {
        std::cout << "WSAStartup error\r\n";
        WSACleanup();
        return -1;
    }

    // Create socket
    SOCKET recSocket = socket(AF_INET,IPPROTO_UDP);
    if (recSocket == INVALID_SOCKET)
    {
        int error = WSAGetLastError();
        std::cout << "Unable to open socket " << error << std::endl;
    }

    // Bind to specific ip address and port
    SOCKADDR_IN receiverAddress;
    receiverAddress.sin_family = AF_INET;
    receiverAddress.sin_port = htons(port);
    inet_pton(AF_INET,&(receiverAddress.sin_addr));

    if (bind(recSocket,(SOCKADDR*)&receiverAddress,sizeof(receiverAddress)) == SOCKET_ERROR)
    {
        std::cout << "Server: bind() Failed! Error: " << WSAGetLastError() << std::endl;
        closesocket(recSocket);
        WSACleanup();
        return -1;

    }

    // Join mcast group
    struct ip_mreq mreq;
    inet_pton(AF_INET,&(mreq.imr_interface.s_addr));
    inet_pton(AF_INET,&(mreq.imr_multiaddr.s_addr));

    if (SOCKET_ERROR == setsockopt(recSocket,IPPROTO_IP,IP_ADD_MEMBERSHIP,(char*)&mreq,sizeof(mreq)))
    {
        std::cout << "Server: setsockopt() Failed! Error: " << WSAGetLastError() << std::endl << std::flush;
        closesocket(recSocket);
        WSACleanup();
        return -1;
    }

    //Spin and wait for packets
    SOCKADDR_IN SenderAddr;
    int SenderAddrSize = sizeof(SenderAddr);
    int receivedFrames = 0;
    while (1)
    {
        int ByteReceived = recvfrom(recSocket,receiveBuffer,sizeof(receiveBuffer),(SOCKADDR*)&SenderAddr,&SenderAddrSize);
        if (ByteReceived > 0)
        {
            printf("\r%04d",++receivedFrames);
        }
        else
        {
            std::cout << "Server: recvfrom() Failed! Error: " << WSAGetLastError() << std::endl;
        }
    }
}

解决方法

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