I've got a class which sends multipart MIME data as a POST request to a
web server.  It works fine with small files, but larger files (still
<50Mb) cause it to throw an OutOfMemory exception:

Exception in thread "Thread-0" java.lang.OutOfMemoryError: Java heap space

I've looked through the relevant code and can't see anywhere that I'm
caching the data being sent, and I really can't see why the memory
consumption would be related to file size.

I've found that if I don't write the file data to the OutputStream
(comment out outStream.write(bytes,0,a);) then it completes OK so it
looks like the OutputStream is caching something - but I can't see any
option to control this.  I've tried flushing after each write, but with
no effect.

A cut down version of the relevant bit of code is below.  Any clues as
to how to debug this are most welcome

Cheers

Simon.

import java.io.*;
import java.net.*;

public class TestFileUpload {

  public  static  void  main(String[]  args)  {
    OutputStream  outStream  =  null;
    try  {
      HttpURLConnection  h  =  (HttpURLConnection)new
URL("http://localhost/cgi-bin/test.cgi").openConnection();

      h.setAllowUserInteraction(false);
      h.setRequestMethod("POST");
      h.setDoOutput(true);
      h.setUseCaches(false);

      h.connect();

      outStream  =  h.getOutputStream();
    }
    catch  (Exception  e)  {
      e.printStackTrace();
    }

    int  byteCount  =  0;

    FileInputStream  fi  =  null;
    try  {
      fi  =  new  FileInputStream(new  File("C:/big.xml"));
    }
    catch  (FileNotFoundException  e)  {
      e.printStackTrace();
    }
    DataInputStream  di  =  new  DataInputStream(fi);

    byte  []  bytes  =  new  byte[1024];

    try  {
        int  a;
        while  ((a  =  di.read(bytes))  >0)  {
        outStream.write(bytes,0,a);
        byteCount+=a;
        }

        outStream.flush();
        outStream.close();
    }

    catch  (IOException  ioe)  {
      ioe.printStackTrace();
    }

  }
}