Re: maximum memory for gcj-compiled executable?

[Lars Andersen <lars at rimfaxe dot com>]

On Fri, 2003-04-04 at 13:44, Lars Andersen wrote:
> Ranjit Mathew wrote:
> >>I have made this simple program that reads a web page, and then does
> >>nothing with it ;)
> >>
> >>Compile it under win32/mingw using Mohan's latest GCC3.3
> >>
> >>Run it. 
> >>
> >>The heap soon stabilizes and stays put (about 1000KB)
> >>
> >>Now open the task manager and watch memory usage slowly grow and grow
> >>and grow....
> > 
> > 
> > Yes, I see this behaviour too. Even after statically allocating
> > "buf" and "output" (and remembering to output.setLength( 0) at the
> > start of read( )) and explicitly closing streams and connections
> > and even omitting the creation of the intermediate strings...i.e.
> > the mere act of reading is causing this increase!
> > 
> > Don't know what's causing it and I wouldn't venture a guess 
> > either. :-(
> > 
> > Ranjit.
> 
> 
> Just tried it reading a file instead of reading a web page.
> This did not exhibit any growing mem usage.
> 
> This is likely a problem in java.net / mingw

I tried modifying TestThread.java (see it in
http://gcc.gnu.org/ml/java/2003-04/msg00054.html ), to write and read
directly to java.net.Socket instead of using java.net.HttpURLConnection.

With this change the memory leak disappears.

Maybe this is a clue to where the bug is.

Please note that this way of conducting a http request is much, MUCH
slower than using java.net.HttpURLConnection, so it takes a while for it
to stabilize...

Here is how the new performRequest() reads :

....
public void performRequest()
{
    String uri = "/index.html";
    String host = "www.apache.org";
    int port = 80;
    
    SocketURL surl = new SocketURL(host);
    surl.setPort( port );  
    surl.setMethod("GET");
    surl.setHeader("Host",""+host+":"+port); 
    surl.connectSocket();
    
    java.io.DataInputStream dis = surl.getData(uri,null);
    String res = surl.readDataInputStream(dis);
    
    System.out.println("Length of page="+res.length() );
 }
....


Attached:

SocketURL.java
TestThread.java

/Lars Andersen

/*
 * TestThread.java
 *
 * Created on April 3, 2003, 3:16 PM
 */

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

/**
 *
 * @author  lars
 */
public class TestThread extends Thread
{
    
    
  /** Creates a new instance of TestThread */
    public TestThread() 
  {
  }
  
  public void run()
  {
      while (true)
      {
        long sleep = 3000;
        try
        {
          System.out.println("\n");  
          Thread.sleep(600);    
          performRequest();
          Thread.sleep(200);    
          performRequest();
          Thread.sleep(200);    
          performRequest();
          Thread.sleep(200);    
          performRequest();
          
          long total = Runtime.getRuntime().totalMemory() / 1024;
          long free = Runtime.getRuntime().freeMemory() / 1024;
          System.out.println("Heap Size "+total);
          System.out.println("Free Heap Size "+free);
    
        }
        catch (InterruptedException ex) {} // ignore exception!
      }
      
      
  }
    
  public void performRequest()
  {
    String uri = "/index.html";
    String host = "www.apache.org";
    int port = 80;
    
    SocketURL surl = new SocketURL(host);
    surl.setPort( port );  
    surl.setMethod("GET");
    surl.setHeader("Host",""+host+":"+port); 
    surl.connectSocket();
    
    java.io.DataInputStream dis = surl.getData(uri,null);
    String res = surl.readDataInputStream(dis);
    
    System.out.println("Length of page="+res.length() );
    
    /*try
    {
      String uri = "/index.html";
      
      java.net.URL url = new java.net.URL("http://www.apache.org"+uri);
      java.net.HttpURLConnection uc = (java.net.HttpURLConnection) url.openConnection();
      
      uc.setRequestMethod("GET");
      uc.connect();
      
      java.io.InputStream is = uc.getInputStream();
      
      
      String res = read(is);
      
      System.out.println("*Length of page="+res.length() );
     
    }
    catch (Exception e) 
    {
      e.printStackTrace(System.out);
    }*/ 
  }
  
  public String read(InputStream is)
  {
    StringBuffer output = new StringBuffer();
    try 
    {
      byte[] buf = new byte[1000];
      int res=0;
      
      res = is.read(buf);
      while(res>0) 
      {
        String s = new String(buf);
        s = s.substring(0,res);
        output.append( s );
        res = is.read(buf);
      }
      is.close();
    }
    catch(IOException exc) 
    {
      exc.printStackTrace(System.out);
    }
    
    return output.toString();
  }
  
  public static void main(String[] args)
  {
    System.out.println("Starting TestThread app");
    
    try
    {
       TestThread tt = new TestThread();
       tt.start();
    }
    catch (Exception e) 
    {
      e.printStackTrace(System.out);
    } 
    
  } 
}

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

public class SocketURL extends Object 
{
  StringBuffer headers = new StringBuffer();
  Socket sock = null;
  String host = "";
  int port = 80;  
  String method = "GET";
  
  String version = "1.1";
  
  
  /** Creates new SocketURL */
  public SocketURL(String host)
  {
    this.host = host;
  }

  public void setPort(int p) { port = p; }
  public void setHost(String h) { host = h; }
  public void setVersion(String v) { version = v; }
  public void setMethod(String m) { this.method = m; }
  
  public void setHeader(String key, String value) 
  { 
    headers.append(key+": "+value+"\r\n"); 
  }
  
  
  public void connectSocket() 
  {  
    int numTries = 0;
    boolean connectOk = false;
    while (!connectOk && numTries++ < 3) 
    {
      try 
      {
        sock = new Socket(host, port);
        connectOk = true;
      } 
      catch (Exception ex) 
      {
        try { Thread.sleep(20); } catch (InterruptedException iEx) {}
      }
    }
  }

  
  
 
  public DataInputStream getData(String path, String request)
  {
    
    try
    {
      
        
      StringBuffer out = new StringBuffer();  
      //System.out.println("2"); 
      DataInputStream inStream = new DataInputStream(sock.getInputStream());
      DataOutputStream outStream = new DataOutputStream(sock.getOutputStream());
      
      
      outStream.writeBytes(method+" "+path+" HTTP/"+version+"\r\n");
      out.append(method+" "+path+" HTTP/"+version+"\r\n");
      
      outStream.writeBytes(headers.toString());
      out.append(headers.toString());
      
      // Send a \r\n to indicate the end of the header
      outStream.writeBytes("\r\n");
      out.append("\r\n");
      // Now send the information you are posting
      
      if (request!=null)
      {
        outStream.writeBytes(request+ "\r\n");
        out.append(request+ "\r\n"); 
      }
      
      return inStream;
    } 
    catch (Exception e) 
    { 
    }
    return null;
  }  
  
  public String readDataInputStream(DataInputStream dis)
  {
    
    StringBuffer output = new StringBuffer();
    try 
    {
      byte[] buf = new byte[1000];
      int res=0;
      
      res = dis.read(buf);
      while(res>0) 
      {
        String s = new String(buf);
        s = s.substring(0,res);
        output.append( s );
        res = dis.read(buf);
      }
      dis.close();
    }
    catch(IOException exc) 
    {
    }
    return ""+output;
  }
}