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A simple GC micro benchmark that creates only objects of 0 lifetime (but as many of them as possible)
* A GC micro benchmark running a given number of threads that create objects of a given size and dereference them immediately
* @author jsound
public class GarbageOnly {
// object size in bytes
private static final int DEFAULT_NUMBEROFTHREADS=8;
private static final int DEFAULT_OBJECTSIZE=100;
private static int numberOfThreads=DEFAULT_NUMBEROFTHREADS;
private static int objectSize=DEFAULT_OBJECTSIZE;
* @param args the command line arguments
public static void main(String[] args) {
// first (optional) argument is the number of threads to run
if( args.length>0 ) {
numberOfThreads = Integer.parseInt(args[0]);
// second (otpional) argument is the size of the objects
if( args.length>1 ) {
objectSize = Integer.parseInt(args[1]);
System.out.println("Creating objects of size "+objectSize+" with "+numberOfThreads+" threads");
// run the configured number of GC producer threads
for(int i=0; i<numberOfThreads; i++) {
new Thread(new GCProducer()).start();
try {
// Let the benchmark run 5 minutes (using the -Xloggc:<filename> JVM parameter)
// For evaluation of the GC rate from the GC log I disregard the first minute as warmup and
// use the average of the remaining 4 minutes as a score value
} catch( InterruptedException iexc) {
public static class GCProducer implements Runnable {
public void run() {
// make object creation as cheap as possible to measure GC performance with
// as little overhead as possible
int osize = objectSize;
while(true) {
// create character arrays of the configured size
char[] garbageObject = new char[osize];
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