Broken pipe (SocketException) despite activity

[Stefan Weber]

Hello

I have a problem with a socket connection. I open a connection to the
server, send some data and close it again. So far, so good. The problem
arises when I want to send more data (eg. 50kbyte). In such a case, the
Client always terminates with a SocketException and the message "broken
pipe". The server is fine (or at least there is no exception).

I was searching and found that this problem comes up when having an
idle connection. But this is not the case in my scenario: the
connection is opened and the sending immediatly begins (also, the
receiving works at the beginning!).

The same problem, when I send smaller packets of data each time, i.e.
50 times a packet of 1kbyte.

Does anybody have an idea what this could be?

Thanks in advance,

Stefan Weber

 

[Gordon Beaton]

I have a problem with a socket connection. I open a connection to the
server, send some data and close it again. So far, so good. The problem
arises when I want to send more data (eg. 50kbyte). In such a case, the
Client always terminates with a SocketException and the message "broken
pipe". The server is fine (or at least there is no exception).

If you closed the connection, then you need to open a new socket
before you can send more data.

If that's not the problem then you need to post your code.

/gordon

 

[Stefan Weber]

I have a problem with a socket connection. I open a connection to the

If you closed the connection, then you need to open a new socket
before you can send more data.

If that's not the problem then you need to post your code.

This is not the problem.

I extracted the problematic code. The client is:

import java.net.*;
import java.io.*;
public class Client
{
public static void main(String[] args) {
byte[] sendData = new byte[1024];
byte[] rcvData = new byte[8];
try {
// connect to the node
Socket socket = new Socket("planetlab02.ethz.ch", 5452);
InputStream is = socket.getInputStream();
OutputStream os = socket.getOutputStream();

for(int i = 0; i < 50; i++) {
os.write(sendData);
os.flush();
System.out.print("written...");
is.read(rcvData);
System.out.println("read...");
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

and the server:


import java.net.*;
import java.io.*;
public class Server {

public static void main(String[] args) {
try {
Socket socket = null;
InputStream is = null;
OutputStream os = null;
ServerSocket serverSocket = new ServerSocket(5452);

// accept connections until thread is terminated
while (true) {
socket = serverSocket.accept();

// if something tried to connect
is = socket.getInputStream();
os = socket.getOutputStream();

byte[] b = new byte[1024];
byte[] a = new byte[8];

for (int i = 0; i < 50; i++) {
is.read(b);
System.out.print("read...");
os.write(a);
os.flush();
System.out.println("written...");
}

socket.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

I know this code doesn't really make sense. But it's taken out of
context to illustrate the problem (which of course still exists). After
a few read/writes, the mentioned error occurs.

Thanks and regards,

Stefan Weber

 

[Gordon Beaton]

I know this code doesn't really make sense. But it's taken out of
context to illustrate the problem (which of course still exists).
After a few read/writes, the mentioned error occurs.

The client will get the exception if the server stops reading and
closes the connection before the client has finished writing.

One problem in the code is that you incorrectly assume that each
read() reads the requested amount, which absolutely cannot be relied
on. Check the return value from read() and compensate for short reads.

Also, the read loop condition should be such that the server gives the
client a chance to close first. You can do that by reading to EOF, or
by determining from the contents of the sent data when the client has
finished writing.

/gordon

 

[Chris Uppal]

is.read(rcvData); ....
is.read(b);

Try modifying your example so that you actually use the returned value from
these read() methods[*]. I suspect your client and server are getting out of
synch and the server is closing the socket before the client has written
everything it wants to.

-- chris

[*] And your real code too if it is written the same way -- it is /never/
correct to ignore the return value from read(); if you are doing so then your
code is already broken, and you may as well fix it before going on to look for
whatever other problems there may be.