GC Test Program

GCTest.java

package demo;

import java.util.ArrayList;
import java.util.List;

public class KillTheGarbageCollector {

	private List<String> outerStore = new ArrayList<>(1_000_000);
	private List<String> oldStore =   new ArrayList<>(1_000_000);
	private static int nThread = 3;

	public static void main(String[] args) {

		for (int i = 0; i < nThread; ++i) {

			new Thread() {
				public void run() {
					long start = System.currentTimeMillis();
					new KillTheGarbageCollector().go();
					long end = System.currentTimeMillis();
					System.out.println(Thread.currentThread() + " runs for " + (end-start) + "ms");
				}
			}.start();
		}
	}

	private void go() {
		long time = System.currentTimeMillis();
		for (int i = 0; i < 100; ++i) {
			if (i % 10 == 0) {
				doOld();
				time = System.currentTimeMillis(); // reset the clock
			}
			for (int j = 0; j < 1000000 / nThread; ++j) {
				outerStore.add(((Integer) j).toString());
			}
			outerStore.clear();
			long t = System.currentTimeMillis();
			//System.out.println("" + (t - time));
			time = t;
		}
	}

	private void doOld() {
		oldStore.clear();
		for (int j = 0; j < 5_000_000 / nThread; ++j) {
			oldStore.add(((Integer) j).toString());
		}
	}

}