Name: dbT83986 Date: 02/17/99


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When sending big amount of data to a OutputStream from a
URLConnection (POST method) in chunks of 5k (for example)
OutputStream does not flush, finishing with an OutOfMemory
Exception.


1. Exact steps to reproduce the problem
   ------------------------------------

   a) Create a new URL object
   b) Obtain its URLConnection
   c) set doOutput and doInput to true
   d) obtain URLConnection's output stream,
   c) an try to send (write) big data in chunks of 5 k. with a loop
   d) Try to flush inside the loop, unsuccessfully.

2. Java SOURCE CODE
   ----------------

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

class Prove extends Object
{
  URL u = null; // URL of cgi that uploads the file
  URLConnection urlCnx = null; // URLConnection of previous URL
  FileInputStream fis = null; // File to send
  String filename = "c:\\tmp\\comm404.exe"; // Size = 27 Mb !!
  public Prove()
  {
    try {
      u = new URL("http://150.1.1.15:8081/cgi-bin/upload.cgi");
      System.out.println("URL = "+u);

      fis = new FileInputStream(filename);
      System.out.println("FIS = "+fis);

    }catch(Exception e) {
      System.err.println("ERROR in constructor:");
      e.printStackTrace();
    }
  }

  public void doUploadMultipart()
  {

    try {
      urlCnx = u.openConnection(); // Get Connection
      urlCnx.setDoInput(true); // RTS: read & write
      urlCnx.setDoOutput(true); //
      urlCnx.setUseCaches(false); // We doesn't want cache
      
      
      urlCnx.setRequestProperty("Content-type","multipart/form-data; boundary=sendfile");
    }
    catch(Exception e)
      {
System.err.println("Error: "+e+"\n");
      }
    
    
    // Now, send the parameters (the file)
    try {
      DataOutputStream printout = new DataOutputStream (urlCnx.getOutputStream());
      
      writeMultipart(printout);
      printout.close(); // Here is were it really flushes
    }catch(IOException e) {
      System.err.println("Error IOException: "+e.getMessage()+"\n");
      e.printStackTrace();
    }

    // We don't reach here, because Exception inside in writeMultipart()
    try
      {
// Read the result (OK, BAD,...)
InputStream is = urlCnx.getInputStream();
BufferedReader d = new BufferedReader(new InputStreamReader(is));
String result = d.readLine();
System.out.println("Result = "+result);
      }
    catch(Exception e)
      {
System.err.println(e);
e.printStackTrace();
      }
  }

  protected void writeMultipart(DataOutputStream os)
  {
    try {
      // Write headers
      printBoundaryBegin(os);
      printMPFieldName(os,"file1");
      printMPFileName(os,filename);
      printDoubleReturn(os);
    }catch(IOException error) {
      System.err.println("ERROR: Writing header Multipart");
      System.err.println("MSG = "+error.getMessage());
      System.err.println("E = "+error);
      error.printStackTrace();
    }
    
    // Send the file content
    int got;
    byte [] buffer=new byte[1024*5]; // We alloc 5 kb buffer
    
    try {
      while((got=fis.read(buffer)) > 0) // While data is available, read ...
{
os.write(buffer,0,got); // ... then write

//***************** T H E P R O B L E M ****************
os.flush(); // ... AND FLUSH (DOES NOT WORK!!!)
//***************** T H E P R O B L E M ****************
}
    }catch(IOException error){
      System.err.println("ERROR reading & writing file");
      System.err.println("MSG = "+error.getMessage());
      System.err.println("E = "+error);
      error.printStackTrace();
    }
    
    try {
      // Imprime fin de boundary y cierra conexion
      printBoundaryEnd(os);
      os.flush();
    }catch(IOException error) {
      System.err.println("ERROR Writing end of boundary");
      System.err.println("MSG = "+error.getMessage());
      System.err.println("E = "+error);
      error.printStackTrace();
    }
  }

  protected void printBoundaryBegin(OutputStream os) throws IOException
  {
    os.write("--sendfile\r\n".getBytes());
    os.flush();
  }

  protected void printBoundaryEnd(OutputStream os) throws IOException
  {
    os.write("\r\n--sendfile--\r\n".getBytes());
    os.flush();
  }

  protected void printMPFieldName(OutputStream os,String fieldname) throws IOException
  {
    os.write(("Content-Disposition: form-data; name=\""+fieldname+"\"").getBytes());
    os.flush();
  }

  protected void printMPFileName(OutputStream os, String filename) throws IOException
  {
    os.write(("; filename=\""+filename+"\"").getBytes());
    os.flush();
  }

  protected void printDoubleReturn(OutputStream os) throws IOException
  {
    os.write("\r\n\r\n".getBytes());
    os.flush();
  }
  
  public static void main(String argv[])
  {
    Prove p = new Prove();

    p.doUploadMultipart();
  }
}

3. Text Error Message
   ------------------

java.lang.OutOfMemoryError:

4. Trace info
   ----------

java.lang.OutOfMemoryError:
at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:95)
at java.io.DataOutputStream.write(DataOutputStream.java:83)
at Prove.writeMultipart(Prove.java:92)
at Prove.doUploadMultipart(Prove.java:47)
at Prove.main(Prove.java:151)

5. java -fullversion
   -----------------

  java full version "JDK1.1.6N"

6. Note
   ----

   a) I have replaced the DataOutputStream with an BufferedOutputStream
      with the same results.
   b) CGI's hangs because header content-length noticed it to
      send more bytes than it really can obtain. So, it hangs
      waiting for read more bytes at fread in stdin.
(Review ID: 54262)
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