Winsock error 10035

The docs say:

10035: WSAEWOULDBLOCK.

Resource temporarily unavailable.

This error is returned from operations on nonblocking sockets that cannot be completed immediately, for example recv when no data is queued to be read from the socket. It is a nonfatal error, and the operation should be retried later. It is normal for WSAEWOULDBLOCK to be reported as the result from calling connect on a nonblocking SOCK_STREAM socket, since some time must elapse for the connection to be established.

WTF???

wtf indeed

This error isn’t an error at all. Pay attention to the last phrase:

10035: WSAEWOULDBLOCK.

Resource temporarily unavailable.

This error is returned from operations on nonblocking sockets that cannot be completed immediately, for example recv when no data is queued to be read from the socket. It is a nonfatal error, and the operation should be retried later. It is normal for WSAEWOULDBLOCK to be reported as the result from calling connect on a nonblocking SOCK_STREAM socket, since some time must elapse for the connection to be established.

In a program, like that crummy msdn example, I wrote:

  // Connect to server.
  if ( connect( g.s, (SOCKADDR*) &clientService, sizeof(clientService) ) == SOCKET_ERROR) {
    
    int err = WSAGetLastError();
    printf( "Failed to connect:  Error code: %d.n", err );
    WSACleanup();
    return;
  }

But what would happen EVERY TIME is 10035: WSAEWOULDBLOCK.

WHY??? I puzzled over this again and again. WHAT IS WSAEWOULDBLOCK??
codegear has:

Abstract: Whenever I try to run my socket program, I get the error WSAEWOULDBLOCK.

Question

Why do I get a WSAEWOULDBLOCK error when I run my program.

Answer

This means that you are setting up your program as a non-blocking sockets program, however the computer is telling you that it would have to create a blocked connection to the socket.

Of all the bullshit…

THAT DOESN’T ANSWER MY QUESTION!!

So, I tried putting it in a loop to see if the state would change:

  // Connect to server.
  while ( connect( g.s, (SOCKADDR*) &clientService, sizeof(clientService) ) == SOCKET_ERROR) {
    
    int err = WSAGetLastError();
    printf( "Failed to connect:  Error code: %d.n", err );
    //WSACleanup();
    //return;
  }

INTERESTINGLY, this is what happens:

10035
10056
10056
10056
10056
10056
10056
10056
.
.
.

Where 10056 is:

10056: WSAEISCONN

Socket is already connected.

A connect request was made on an already-connected socket. Some implementations also return this error if sendto is called on a connected SOCK_DGRAM socket (for SOCK_STREAM sockets, the to parameter in sendto is ignored) although other implementations treat this as a legal occurrence.

WHAT???? WOOHOO . . . ? ITS CONNECTED!!! BUT WHY??

Ah. I get it. Read that red italicized text again:

10035: WSAEWOULDBLOCK.

Resource temporarily unavailable.

This error is returned from operations on nonblocking sockets that cannot be completed immediately, for example recv when no data is queued to be read from the socket. It is a nonfatal error, and the operation should be retried later. It is normal for WSAEWOULDBLOCK to be reported as the result from calling connect on a nonblocking SOCK_STREAM socket, since some time must elapse for the connection to be established.

So it would SEEM that since 10035 WSAEWOULDBLOCK is a non-fatal error, you should IGNORE IT TRY AND USE THE SOCKET ANYWAY.

If you want to use an if statement like the crummy MSDN example (which is the reason this took so long to get past!!)

  // Connect to server.
  while ( connect( g.s, (SOCKADDR*) &clientService, sizeof(clientService) ) == SOCKET_ERROR) {
    
    int err = WSAGetLastError();
    printf( "Failed to connect:  Error code: %d.n", err );
    printf( errCodes[ err ] );
    //WSACleanup();
    //return;

    // these errors are non-fatal:  10056 means already connected
    // and 10035 means its trying really hard to connect
    // and you should just give it a moment.
    if( err == 10056 || err == 10035 )
      break;
  }

Error 10035 is WSAWOULDBLOCK, which is NOT a fatal error, but you are treating it as if it were.

You are obviously using a non-blocking socket, or you wouldn’t be getting this «error» in the first place. As such, you need to handle the possibility that send() may fail to block the calling thread (because the receiver doesn’t have enough buffer space to receive more data).

Simply retry the same send() operation again, preferably preceeding it with a call to select() to wait (with an optional timeout) for the receiver to free up some buffer space before you send data again.

Try something more like this:

BOOL CUser::SendMessageA(void)
{
    if (Socket.Socket == INVALID_SOCKET)
    {
        Socket.nSendPosition = 0;
        Socket.nSentPosition = 0;
        return FALSE;
    }

    if (Socket.nSentPosition > 0)
        RefreshSendBuffer();

    if (Socket.nSendPosition > MAX_BUFFER || Socket.nSendPosition < 0 || Socket.Socket == INVALID_SOCKET)
    {
        Log(SERVER_SIDE, LOG_ERROR, "Send, 1");
        return FALSE;
    }

    if (Socket.nSentPosition > Socket.nSendPosition || Socket.nSentPosition > MAX_BUFFER || Socket.nSentPosition < 0)
    {
        Log(SERVER_SIDE, LOG_ERROR, "Send, 2");
        Socket.nSendPosition = 0;
        Socket.nSentPosition = 0;
    }

    while (Socket.nSentPosition < Socket.nSendPosition) 
    {
        INT32 numSent = send(Socket.Socket, (char*)Socket.sendBuffer + Socket.nSentPosition, Socket.nSendPosition - Socket.nSentPosition, 0);
        if (numSent != SOCKET_ERROR)
            Socket.nSentPosition += numSent;
        else
        {
            INT32 err = WSAGetLastError();
            if (err != WSAWOULDBLOCK)
            {
                CheckIdle(clientId);
                Socket.Error++;
                if (Socket.Error < 10)
                    Log(clientId, LOG_INGAME, "Erro no envio do pacote. Total a ser enviado: %d. Error: %d", Socket.nSendPosition, err);
                return FALSE;
            }

            // optionally call select() here to wait for the socket to become writable again...
        }
    }

    Socket.nSendPosition = 0;
    Socket.nSentPosition = 0;
    return TRUE;
}

Or, if you want the function to exit when a blockage occurs, and not wait for the data to fully send, but to finish sending at a later time:

BOOL CUser::SendMessageA(void)
{
    if (Socket.Socket == INVALID_SOCKET)
    {
        Socket.nSendPosition = 0;
        Socket.nSentPosition = 0;
        return FALSE;
    }

    if (Socket.nSentPosition > 0)
        RefreshSendBuffer();

    if (Socket.nSendPosition > MAX_BUFFER || Socket.nSendPosition < 0 || Socket.Socket == INVALID_SOCKET)
    {
        Log(SERVER_SIDE, LOG_ERROR, "Send, 1");
        return FALSE;
    }

    if (Socket.nSentPosition > Socket.nSendPosition || Socket.nSentPosition > MAX_BUFFER || Socket.nSentPosition < 0)
    {
        Log(SERVER_SIDE, LOG_ERROR, "Send, 2");
        Socket.nSendPosition = 0;
        Socket.nSentPosition = 0;
    }

    INT32 numSent = send(Socket.Socket, (char*)Socket.sendBuffer + Socket.nSentPosition, Socket.nSendPosition - Socket.nSentPosition, 0);
    if (numSent != SOCKET_ERROR)
        Socket.nSentPosition += numSent;
    else
    {
        INT32 err = WSAGetLastError();
        if (err != WSAWOULDBLOCK)
        {
            CheckIdle(clientId);
            Socket.Error++;
            if (Socket.Error < 10)
                Log(clientId, LOG_INGAME, "Erro no envio do pacote. Total a ser enviado: %d. Error: %d", Socket.nSendPosition, err);
            return FALSE;
        }
    }

    if (Socket.nSentPosition >= Socket.nSendPosition)
    {
        Socket.nSendPosition = 0;
        Socket.nSentPosition = 0;
    }

    return TRUE;
}

***Note***

If you are using a .NET, Java, or related IPWorks or IPWorks SSL toolkit, then in addition to the information below, you can set the DefaultTimeout property to a positive value and perform simultaneous sends by utilizing a background thread for each send. This is only possible in .NET and Java because those toolkits are thread-safe.

In the IPWorks and IPWorks SSL toolkits, winsock error 10035 means «Resource not available» or «Operation would block».
This error happens when the winsock buffer of either the client or server side become full.

Here are two situations in which you might see Winsock error 10035:

• You’re trying to send a massive amount of information through the socket, so the output buffer of the system becomes full.
• You’re trying to send data through the socket to the remotehost, but the remotehost input buffer is full (because its receiving data slower than you’re sending it).

When you send data — you really send it to the TCP/IP subsystem of your machine (ie winsock). The system buffers this
data (in the OutBuffer) and begins sending it to the remote host as fast as it can (which of course is only as fast
as the receiver can receive it). If the OutBuffer gets filled, because you are sending data faster than the system
can send it — you’ll get Winsock error 10035.

For IPWorks users, with the exception of asynchronous components like IPPort and IPDaemon, you will never have to worry about this error because the components deal with them for you
automatically. The IPPort and IPdaemon components are the building blocks with which you can build any TCP/IP solution, they give you complete control over everything.

In order to deal with this when using IPPort or IPDaemon, just catch the Winsock 10035 error and wait for the component’s
ReadyToSend event to fire (this fires when the system is able to send data again). At that time, you can continue sending
your data, starting with that which failed. For example, the c# code below will loop until the length of the data to be sent is 0.
If all goes normally, this loop will only be entered once and all of the data will be sent. After a while, if the output buffer
fills up, the SetDataToSend inside the loop will fail with the Winsock 10035 error. The code will wait for the
ReadyToSend event (the ready boolean flag), and loop. SetDataToSend will be called again, successfully.

note: The ReadyToSend event will only fire if none of the data was able to be sent. So the code below will
only wait for the event if BytesSent equals 0. Otherwise, if some of the data was able to be sent, the code will loop
immediately and attempt to resend the remaining data.


while (length > 0) { //this means that we have some bytes to send
try
{
ready = false;
ipport1.SetDataToSend(TextB, offset, length);
length -= ipport1.BytesSent;
tbStatus.AppendText(ipport1.BytesSent.ToString() + " bytes sent." + "rn");
}
catch (nsoftware.IPWorks.IPWorksException ex1)
{
if (ex1.Code == 135) //WOULDBLOCK Error
{
if (ipport1.BytesSent == 0) while (!ready) { ipport1.DoEvents(); }
length -= ipport1.BytesSent; offset += ipport1.BytesSent;
tbStatus.AppendText("Retrying Send..." + "rn");
}
}
}


1. Mar 2nd, 2009, 07:12 AM

   
   

   #1

   

   Thread Starter

   
   Hyperactive Member
   

   

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   [RESOLVED] [winsock] error 10035
   

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2. Mar 2nd, 2009, 07:26 AM

   
   

   #2

   

   
   Member
   

   

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   Re: [winsock] error 10035
   

   Are you under Windows Vista? I seem to encounter this problem when I was running Vista and VB was unable to bind to a local port.

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3. Mar 2nd, 2009, 08:09 AM

   
   

   #3

   

   Thread Starter

   
   Hyperactive Member
   

   

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   Re: [winsock] error 10035
   

   i am using windows 7 actually

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4. Mar 2nd, 2009, 11:56 AM

   
   

   #4

   Re: [winsock] error 10035
   

   Error 10035:

   Problem: Resource temporarily unavailable.

   Solution: This is a temporary condition and later calls to the same routine may complete normally. The socket is marked as non-blocking (non-blocking operation mode), and the requested operation is not complete at this time.

   Since it occurs on the server side only you have no way of knowing this on the client side so I do not know how you could repeat the call.

   Are you absolutely sure there is no client side evidence of this occurance? Do you have a Winsock_Error event on the client(s) applications to trap errors when they occur?

   Last edited by jmsrickland; Mar 2nd, 2009 at 12:01 PM.

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5. Mar 2nd, 2009, 12:08 PM

   
   

   #5

   

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   Hyperactive Member
   

   

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   Re: [winsock] error 10035
   

   Originally Posted by jmsrickland

   Error 10035:

   Problem: Resource temporarily unavailable.

   Solution: This is a temporary condition and later calls to the same routine may complete normally. The socket is marked as non-blocking (non-blocking operation mode), and the requested operation is not complete at this time.

   Since it occurs on the server side only you have no way of knowing this on the client side so I do not know how you could repeat the call.

   Are you absolutely sure there is no client side evidence of this occurance? Do you have a Winsock_Error event on the client(s) applications to trap errors when they occur?

   yes i am 100% sure there is nothing happening on the client side.. but on server side it accepts the connection and then moves on to server_error event.. i have just installed sp6 on my machine.. since then i am not having any problem.. i will give it a day ..if everything works fine i shall mark this thread resolved.. for even i did google around about this error.. everyone were facing problems like mine but there was no solution .. anywayz thank you jmsrickland u are always there to help ..

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6. Mar 2nd, 2009, 12:58 PM

   
   

   #6

   

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   Hyperactive Member
   

   

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   Re: [winsock] error 10035
   

   the problem still exists.. after a successful connection why does the server throw an error number 10035?

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7. Mar 2nd, 2009, 01:55 PM

   
   

   #7

   Re: [winsock] error 10035
   

   OK, I will ask you again. Do you have a Winsock_Error(Index) event in your client application and are you checking for any and all errors? If an error occurs at the server side an error should also occur at the client side.

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8. Mar 2nd, 2009, 10:12 PM

   
   

   #8

   

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   Hyperactive Member
   

   

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   Re: [winsock] error 10035
   

   Originally Posted by jmsrickland

   OK, I will ask you again. Do you have a Winsock_Error(Index) event in your client application and are you checking for any and all errors? If an error occurs at the server side an error should also occur at the client side.

   no nothing happens on the client side.. if i don’t add the sub «winsock_error()» on the server side..then it works fine.. what i mean is ..even with the error the connection is still there and works most of the time… i rechecked and rechecked my codes and i found out that although different socks from the client are being connected to different socks in the server .. the data arrival event is handled by the same socks for different client.. is this an issue ??

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9. Mar 2nd, 2009, 10:40 PM

   
   

   #9

   Re: [winsock] error 10035
   

   the data arrival event is handled by the same socks for different client.. is this an issue ??

   Yes! Different clients must have different sockets on the server side

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10. Mar 2nd, 2009, 11:55 PM

    
    

    #10

    Re: [winsock] error 10035
    

    This error usually occurs in programs that do not drive output using the SendComplete event. If you call SendData a subsequent time without waiting for SendComplete on the previous send you can get this error if there is no room in the underlying socket’s send buffer.

    Getting the error on Accept seems very odd, but it seems to be possible… hmm, are you sure you don’t SendData right away? I’ve never seen this.

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11. Mar 3rd, 2009, 05:28 AM

    
    

    #11

    

    Thread Starter

    
    Hyperactive Member
    

    

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    Re: [winsock] error 10035
    

    phew! i finally got it working.. i can connect more than 3000 sockets from the client side to the server which in turn will use the same amount of sockets..
    no problem while connecting ..or sending messages..how over i have one issue.. i don’t know if its normal or my codes.. as the socks on the client side send data the data arrival in the server is fired only after all the socks in the client side sends the data.. it would be better if the data are process as it is being sent.. i am uploading my project perhaps one of you could take a look if you are free.. thank you..

    Last edited by pannam; Mar 4th, 2009 at 07:33 PM.

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12. Mar 4th, 2009, 07:42 PM

    
    

    #12

    

    Thread Starter

    
    Hyperactive Member
    

    

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    Re: [winsock] error 10035
    

    now, all’s working fine.. i made some adjustments. and its all done.. now.. the transactions take simultaneously ..for those who want multi connection [maximum connection]on multiple server ..this might come handy.. i am uploading the project..

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THE INFORMATION IN THIS ARTICLE APPLIES TO:

• All Windows-based products

DISCUSSION

The table below lists some common Winsock error codes. Also refer to the Microsoft MSDN Library article «Winsock Error Codes» at http://msdn.microsoft.com/en-us/library/aa924071.aspx.