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Slow data transfer rate on a remote computer

Hi folks, Stackoverflow!

I am creating an IOCP server, and so far I have fixed most of the problems, but I still remain and I do not know where to start. When I run the client / server on my machine, everything is fine and dandy. It matches the speed of the Windows SDK Sample, perhaps a little faster and definitely uses less CPU cycle. However, when I start the client from a separate computer, the transfer rate is 37 KB / s and has a latency of 200 ms at both ends (as opposed to 0). Now, if I connect the client to the sample SDK server, I do not have this problem, so something is wrong with my code. As far as I know, sockets are initialized in exactly the same way with the same parameters. I also ran my server in the profiler to check for a bottleneck, but I could not find it. Also, the computers I tried it onwere connected to the same gigabit switch (with a gigabit adapter). I know this is vague, but this is because I could not pinpoint the problem so far, and I would be infinitely grateful if any of you guys could point me in the right direction.

Greetings

-Roxy

EDIT2: After Mike advised, I did some code research and found out that when a remote client connects to the server most of the time, the code is waiting on GetQueuedCompletionStatus. This suggests that the I / O request just takes a lot of time, but I still don't understand why. This only happens when the client is on a remote computer. I think this has something to do with setting up sockets or how I send a request, but I see no difference with the sample code.

Any ideas?

EDIT (Added Code Sample):

Ok, here it is! It is not very, though!

If you have the Windows SDK installed, you can connect to it using the iocpclient sample (Program Files \ Microsoft SDKs \ Windows \ v7.1 \ Samples \ netds \ winsock \ iocp \ client) and change its default port on the line From 73 to 5000.

, , , , , iocpclient 37 /... , , 800 /. , .

#pragma comment(lib, "Ws2_32.lib")

#include <WinSock2.h>
#include <stdio.h>

unsigned int connection = 0;
unsigned int upload = 0;
unsigned int download = 0;

#define IO_CONTEXT_COUNT 5

class NetClientHost
{
friend class gNetProtocolHost;
public:
enum Operation
{
    kOperationUnknown,
    kOperationRead,
    kOperationWrite,
};

struct ClientData
{
    SOCKET           socket;
};

struct IOContext
{
    WSAOVERLAPPED    overlapped;
    WSABUF           wsaReceiveBuf;
    WSABUF           wsaSendBuf;
    char            *buf;
    char            *TESTbuf;
    unsigned long    bytesReceived;
    unsigned long    bytesSent;
    unsigned long    flags;
    unsigned int     bytesToSendTotal;
    unsigned int     remainingBytesToSend;
    unsigned int     chunk;
    Operation        operation;
};

NetClientHost()
{
    memset((void *) &m_clientData, 0, sizeof(m_clientData));
}

NetClientHost::IOContext *NetClientHost::AcquireContext()
{
    while (true)
    {
        for (int i = 0; i < IO_CONTEXT_COUNT; ++i)
        {
            if (!(m_ioContexts + i)->inUse)
            {
                InterlockedIncrement(&(m_ioContexts + i)->inUse);
                //ResetEvent(*(m_hContextEvents + i));

                if ((m_ioContexts + i)->ioContext.TESTbuf == 0)
                    Sleep(1);

                return &(m_ioContexts + i)->ioContext;
            }
        }
        //++g_blockOnPool;
        //WaitForMultipleObjects(IO_CONTEXT_COUNT, m_hContextEvents, FALSE, INFINITE);
    }   
}

const ClientData *NetClientHost::GetClientData() const
{
    return &m_clientData;
};

void NetClientHost::Init(unsigned int bufferSize)
{   
    _InitializeIOContexts(bufferSize ? bufferSize : 1024);
}

void NetClientHost::ReleaseContext(IOContext *ioContext)
{
    int i = sizeof(_IOContextData), j = sizeof(IOContext);
    _IOContextData *contextData = (_IOContextData *) (((char *) ioContext) - (i - j));
    InterlockedDecrement(&contextData->inUse);
    //SetEvent(*(m_hContextEvents + contextData->index));
}   

struct _IOContextData
{
    unsigned int index;
    volatile long inUse;        
    IOContext ioContext;
};

ClientData                    m_clientData;
_IOContextData               *m_ioContexts;
HANDLE                       *m_hContextEvents;

void _InitializeIOContexts(unsigned int bufferSize)
{
    m_ioContexts = new _IOContextData[IO_CONTEXT_COUNT];
    m_hContextEvents = new HANDLE[IO_CONTEXT_COUNT];

    memset((void *) m_ioContexts, 0, sizeof(_IOContextData) * IO_CONTEXT_COUNT);

    for (int i = 0; i < IO_CONTEXT_COUNT; ++i)
    {
        (m_ioContexts + i)->index = i;

        (m_ioContexts + i)->ioContext.buf = new char[bufferSize];
        (m_ioContexts + i)->ioContext.wsaReceiveBuf.len = bufferSize;
        (m_ioContexts + i)->ioContext.wsaReceiveBuf.buf = (m_ioContexts + i)->ioContext.buf;
        (m_ioContexts + i)->ioContext.TESTbuf = new char[10000];
        (m_ioContexts + i)->ioContext.wsaSendBuf.buf = (m_ioContexts + i)->ioContext.TESTbuf;

        *(m_hContextEvents + i) = CreateEvent(0, TRUE, FALSE, 0);
    }
}
void _SetSocket(SOCKET socket)
{
    m_clientData.socket = socket;
}
};



bool WriteChunk(const NetClientHost *clientHost, NetClientHost::IOContext *ioContext)
{
int status;

status = WSASend(clientHost->GetClientData()->socket, &ioContext->wsaSendBuf, 1, &ioContext->bytesSent, ioContext->flags, &ioContext->overlapped, 0);
if (status == SOCKET_ERROR && WSAGetLastError() != WSA_IO_PENDING)
{
    // ...
    return false;
}

return true;
}

bool Write(NetClientHost *clientHost, void *buffer, unsigned int size, unsigned int chunk)
{
//__ASSERT(m_clientHost);
//__ASSERT(m_clientHost->GetClientData()->remainingBytesToSend == 0);

NetClientHost::IOContext *ioContext = clientHost->AcquireContext();

if (!chunk)
    chunk = size;

ioContext->wsaSendBuf.buf = ioContext->TESTbuf;

ioContext->operation                = NetClientHost::kOperationWrite;
ioContext->flags                    = 0;
ioContext->wsaSendBuf.buf = new char[size];
memcpy((void *) ioContext->wsaSendBuf.buf, buffer, chunk);
ioContext->wsaSendBuf.len           = chunk;    
ioContext->chunk                    = chunk;
ioContext->bytesToSendTotal         = size;
ioContext->remainingBytesToSend     = size;

return WriteChunk(clientHost, ioContext);
}



void Read(NetClientHost *clientHost)
{   
NetClientHost::IOContext *ioContext = clientHost->AcquireContext();
int status;

memset((void *) ioContext, 0, sizeof(NetClientHost::IOContext));
ioContext->buf = new char[1024];
ioContext->wsaReceiveBuf.len = 1024;
ioContext->wsaReceiveBuf.buf = ioContext->buf;

ioContext->flags = 0;
ioContext->operation = NetClientHost::kOperationRead;

status = WSARecv(clientHost->GetClientData()->socket, &ioContext->wsaReceiveBuf, 1, &ioContext->bytesReceived, &ioContext->flags, &ioContext->overlapped, 0);
int i = WSAGetLastError();
if (status == SOCKET_ERROR && WSAGetLastError() != WSA_IO_PENDING)
{
    // ...
}   
}

bool AddSocket(HANDLE hIOCP, SOCKET socket)
{
++connection;

int bufSize = 0;
LINGER lingerStruct;
lingerStruct.l_onoff = 1;
lingerStruct.l_linger = 0;
setsockopt(socket, SOL_SOCKET, SO_SNDBUF, (char *) &bufSize, sizeof(int));
setsockopt(socket, SOL_SOCKET, SO_RCVBUF, (char *) &bufSize, sizeof(int));
setsockopt(socket, SOL_SOCKET, SO_LINGER, (char *) &lingerStruct, sizeof(lingerStruct) ); 

NetClientHost *clientHost = new NetClientHost;

clientHost->_InitializeIOContexts(1024);
clientHost->Init(0);
clientHost->_SetSocket(socket);

// Add this socket to the IO Completion Port
CreateIoCompletionPort((HANDLE) socket, hIOCP, (DWORD_PTR) clientHost, 0);

Read(clientHost);
return true;
}

int read = 0, write = 0;

DWORD WINAPI WorkerThread(LPVOID param)
{
LPOVERLAPPED overlapped;
NetClientHost *clientHost;
HANDLE hIOCP = (HANDLE) param;
DWORD ioSize;
BOOL status;

while (true)
{
    status = GetQueuedCompletionStatus(hIOCP, &ioSize, (PULONG_PTR) &clientHost, (LPOVERLAPPED *) &overlapped, INFINITE);

    if (!(status || ioSize))
    {
        --connection;
        //_CloseConnection(clientHost);
        continue;
    }

    NetClientHost::IOContext *ioContext = (NetClientHost::IOContext *) overlapped;

    switch (ioContext->operation)
    {
    case NetClientHost::kOperationRead:
        download += ioSize;
        Write(clientHost, ioContext->wsaReceiveBuf.buf, ioSize, 0);
        write++;
        clientHost->ReleaseContext(ioContext);
        break;

    case NetClientHost::kOperationWrite:
        upload += ioSize;
        if (ioContext->remainingBytesToSend)
        {
            ioContext->remainingBytesToSend -= ioSize;
            ioContext->wsaSendBuf.len = ioContext->chunk <= ioContext->remainingBytesToSend ? ioContext->chunk : ioContext->remainingBytesToSend; // equivalent to min(clientData->chunk, clientData->remainingBytesToSend);
            ioContext->wsaSendBuf.buf += ioContext->wsaSendBuf.len;
        }

        if (ioContext->remainingBytesToSend)
        {       
            WriteChunk(clientHost, ioContext);
        }
        else
        {
            clientHost->ReleaseContext(ioContext);              
            Read(clientHost);
            read++;
        }
        break;
    }
}

return 0;
}

DWORD WINAPI ListenThread(LPVOID param)
{
SOCKET sdListen = (SOCKET) param;

HANDLE hIOCP = CreateIoCompletionPort(INVALID_HANDLE_VALUE, 0, 0, 0);
CreateThread(0, 0, WorkerThread, hIOCP, 0, 0);
CreateThread(0, 0, WorkerThread, hIOCP, 0, 0);
CreateThread(0, 0, WorkerThread, hIOCP, 0, 0);
CreateThread(0, 0, WorkerThread, hIOCP, 0, 0);

while (true)
{
    SOCKET as = WSAAccept(sdListen, 0, 0, 0, 0);
    if (as != INVALID_SOCKET)
        AddSocket(hIOCP, as);
}
}

int main()
{
SOCKET      sdListen;
SOCKADDR_IN si_addrlocal;   
int         nRet;   
int         nZero = 0;   
LINGER      lingerStruct;   

WSADATA wsaData;
WSAStartup(0x202, &wsaData);

sdListen = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_IP, NULL, 0, WSA_FLAG_OVERLAPPED);    
si_addrlocal.sin_family = AF_INET;   
si_addrlocal.sin_port = htons(5000);   
si_addrlocal.sin_addr.s_addr = htonl(INADDR_ANY);          
nRet = bind(sdListen, (struct sockaddr *)&si_addrlocal, sizeof(si_addrlocal));   
nRet = listen(sdListen, 5);

nZero = 0;   
nRet = setsockopt(sdListen, SOL_SOCKET, SO_SNDBUF, (char *) &nZero, sizeof(nZero));   
nZero = 0;   
nRet = setsockopt(sdListen, SOL_SOCKET, SO_RCVBUF, (char *)&nZero, sizeof(nZero));
lingerStruct.l_onoff = 1;   
lingerStruct.l_linger = 0; 
nRet = setsockopt(sdListen, SOL_SOCKET, SO_LINGER, (char *)&lingerStruct, sizeof(lingerStruct) );

CreateThread(0, 0, ListenThread, (LPVOID) sdListen, 0, 0);

HANDLE console = GetStdHandle(STD_OUTPUT_HANDLE);
while (true)
{
    COORD c = {0};
    SetConsoleCursorPosition(console, c);
    printf("Connections: %i                      \nUpload: %iKB/s               \nDownload: %iKB/s              ", connection, upload * 2 / 1024, download * 2 / 1024);
    upload = 0;
    download = 0;
    Sleep(500);
}



return 0;
}
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- wirehark, . , .

BTW: , , . , , . . , Zoom.

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Source: https://habr.com/ru/post/1792344/

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