[Jython-dev] instanceof vs reflect benchmark hacks explored Re: The future of CollectionProxy

[James N. <jam...@ya...>]

finn

interesting benchmark, interesting results.  what a performance rift.

the conversation has uncovered a general irrelevance of the coding style
details, there is a huge win in writing the alternative reflection code for
jdk1.4 and keeping instanceof for ibm. (and a huge win in avoiding jdk 1.3)

perhaps a bogo-reflection-mips score could load alternative classes to do
collection class introspections.


experimentation results:

first, your benchmark as-is on my dual celeron 500 w2k:
java version "1.3.1_01" Java(TM) 2 Runtime Environment, Standard Edition
(build 1.3.1_01) Java HotSpot(TM) Client VM (build 1.3.1_01, mixed mode)

cd c:/tmp/
/opt/jdk/bin/javac x.java;/opt/jdk/bin/java x
instanceof 7500
reflect 12656
instanceof 7812
reflect 12610
instanceof 6984
reflect 11563
instanceof 7015
reflect 11469

2nd, after adding some inner nameless classes, sprinkling a few statics and
finals and removing the new [0]'s, perhaps invalidating the intent of the
benchmarks...

instanceof 7563
reflect x - 11719
instanceof 8844
reflect x$1 - 24234
instanceof 9063
reflect x$2 - 22531

3rd, making "call" final and static  (code below).
reflect x - 9500
reflect x$1 - 23844
reflect x$2 - 22031

...looping on " o.getClass().getMethod(intern_methodname,
no_Class).invoke(o,no_Object);"
instanceof 7765
reflect x - 118641
reflect x$1 - 119734
reflect x$2 - 116109

...looping on "call()"
reflect x - 47
reflect x - 47
reflect x - 32

...making call non-static non-final looping on ((x)o).call()
reflect x - ~157

...making call final looping as above
reflect x - ~93.5

---
import java.lang.reflect.*;

public class x {

    public final static void main(String args[]) throws Exception {
	meassure(new x (), true);
	meassure(new Object(){public void call() { cnt++; }},true );
	meassure(new Object(){public final void call() { cnt++; }},true );
    }

    public static  final Class[] no_Class=new Class[]{};
    public static final Object[] no_Object=new Object[]{};
    private final static String intern_methodname="call".intern();

    public final static void meassure(Object o, boolean print)
	throws Exception
    {
	long now;
	int i;
	Class xcls;
	Method m;

	now = System.currentTimeMillis();
	for (i = 0; i < LOOPS; i++) {
	    if (o instanceof java.util.Vector) { cnt++; }
	    if (o instanceof java.util.Dictionary) { cnt++; }
	    //if (o instanceof java.util.Enumeration) { cnt++; }
	    if (o instanceof java.util.List) { cnt++; }
	    if (o instanceof java.util.Collection) { cnt++; }
	    if (o instanceof java.util.Map) { cnt++; }
	    //if (o instanceof java.util.Iterator) { cnt++; }
	    if (o instanceof x) { cnt++; }
	}
	System.out.println("instanceof " +
			   (System.currentTimeMillis() - now));

	xcls = o.getClass();
	m = xcls.getMethod(intern_methodname, no_Class);
	now = System.currentTimeMillis();

	for (i = 0; i < LOOPS; i++) {
	    m.invoke(o, no_Object);
	}
	System.out.println("reflect " +o.getClass().getName()+" - "+
(System.currentTimeMillis() - now));
    }

    public static final int LOOPS = 3000000;
    static int cnt = 0;
    public static final  void call() { cnt++; }
}


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