Created
November 2, 2013 07:01
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Flawed benchmark for reflection performance of Java. Don't do this. Circa 2005.
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import java.util.Date; | |
import java.lang.reflect.Method; | |
import java.lang.reflect.InvocationTargetException; | |
public class Benchmark { | |
public static int method(int parameter) { | |
return parameter%3 > 2 ? System.identityHashCode(new Date()) : -1; | |
} | |
public static void main(String[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException { | |
long startInvocation = System.nanoTime(); | |
for (int i = 0; i < 1000; i++) { | |
method((int) System.currentTimeMillis()%3); | |
} | |
long invocation = System.nanoTime() - startInvocation; | |
System.out.println("direct invocation (ns) = " + invocation); | |
long startReflection = System.nanoTime(); | |
for (int i = 0; i < 1000; i++) { | |
Method rmethod = Foo.class.getMethod("method", int.class); | |
rmethod.invoke(null, (int) System.currentTimeMillis()%3); | |
} | |
long reflection = System.nanoTime() - startReflection; | |
System.out.println("reflection (ns) = " + reflection); | |
long startMI = System.nanoTime(); | |
for (int i = 0; i < 1000; i++) { | |
MethodInvoker mi = new MethodInvoker(Foo.class.getMethod("method", int.class)); | |
mi.invoke(null, (int) System.currentTimeMillis()%3); | |
} | |
long mi = System.nanoTime() - startMI; | |
System.out.println("MI (ns) = " + reflection); | |
System.out.println("slower = " + (float)invocation/reflection); | |
} | |
} |
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import java.lang.reflect.Method; | |
public class MethodInvoker { | |
final Method method; | |
public MethodInvoker(Method method) { | |
this.method = method; | |
} | |
} |
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