Re: debug output problem in ObjectInputStream

[Bryce McKinlay]

Per Bothner wrote:

> Having dumpElement[ln] as separate
> methods has the advantage that it could over overridden, but
> it seems like poinles generality.  So if we want to keep the
> debugging printout, I suggest:
>
>   if (Configuration.DEBUG && dump)
>     for (int i=0, len=Array.getLength(array); i < len; i++)
>       System.out.println("  ELEMENT[" + i + "]=" + Array.get(array, i));
>
> This makes it possible for a compiler to do the optimization to
> multiple print calls that my patch does. 


I was originally hoping that the dumpElement() methods would get inlined 
and the compiler would figure out that the code could be removed, but 
you're right in that even if inlining worked properly the arguments 
would still have to be evaluated unless it could also figure out that 
the StringBuffer methods etc had no side-effects.

I agree that we should put the "if (Configuration.DEBUG ..." at the call 
site to fix this. However, fixing this doesn't really help our extremely 
crap serialization performance. eg the attached test runs more than 45X 
slower with GCJ than JDK 1.4! Serialization needs some work...

regards

Bryce.


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

public class SerTest3
{
  static void showUsage()
  {
    System.err.println("Usage: SerTest3 <read|write>");
    System.exit(1);  
  }
  
  public static void main(String[] args) 
    throws IOException, FileNotFoundException, ClassNotFoundException
  {
    if (args.length == 0)
      showUsage();
    
    HashMap hm = null;    
    long start = System.currentTimeMillis();
    
    if (args[0].equals("write"))
      {
        hm = makeHugeHashMap();
        System.out.println ("map created, writing it out...");
        ObjectOutputStream out = 
          new ObjectOutputStream(new FileOutputStream("test.ser"));

        out.writeObject(hm);
        out.close();
      }
    else if (args[0].equals("read"))
      {      
        ObjectInputStream in = 
          new ObjectInputStream(new FileInputStream("test.ser"));

        hm = (HashMap) in.readObject();
      }
    else
      showUsage();
      
    System.out.println(hm.hashCode());
    System.out.println(System.currentTimeMillis() - start + "ms elapsed.");
  }
  
  static HashMap makeHugeHashMap()
  {
    HashMap hm = new HashMap();
    for (int i=0; i < 200; i++)
    {
      ArrayList al = new ArrayList();
      for (int j=0; j < 1000; j++)
      {
        al.add (Integer.toString(i - j));
      }
      Integer integer = new Integer(i);
      hm.put(integer, al);
    }
    return hm;
  }
}