SelfReporterTest.java

package org.gridkit.jvmtool.gcflow;

import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;

import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;

import org.junit.Test;

public class SelfReporterTest {

	private List<GcAdapter> adapters = new ArrayList<GcAdapter>();
	
	public void run(int seconds) {
		long deadline = System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(seconds);
		while(System.currentTimeMillis() < deadline) {
			for(GcAdapter a: adapters) {
				a.report();
			}
			long nextRep = System.nanoTime() + TimeUnit.MILLISECONDS.toNanos(50);
			while(System.nanoTime() < nextRep) {
				Random rnd = new Random();
				List<String> garbage = new ArrayList<String>();
				for(int i = 0; i != 10000; ++i) {
					int n = rnd.nextInt(512) + 128;
					StringBuilder sb = new StringBuilder();
					for(int j = 0; j != n; ++j) {
						sb.append(rnd.nextInt());
					}
					garbage.add(sb.toString());
				}
			}
			LockSupport.parkNanos(1);			
		}
	}	
	
	public void addToAll(GarbageCollectionSampler sampler) throws MalformedObjectNameException, IOException {
		for(ObjectName gc: ManagementFactory.getPlatformMBeanServer().queryNames(GcKnowledgeBase.COLLECTORS_PATTERN, null)) {
			GcAdapter a = new GcAdapter(ManagementFactory.getPlatformMBeanServer(), gc, sampler);
			adapters.add(a);
		}
	}
	
	@Test
		public void simple_report() throws MalformedObjectNameException, IOException {
			addToAll(new SimpleReporter());
			run(20);
		}

	private final class SimpleReporter implements GarbageCollectionSampler {
		@Override
		public void report(String algoName, int eventsMissed, GcReport info) {
			if (eventsMissed > 0) {
				System.out.println("Missed " + eventsMissed + " events for [" + algoName + "]");
			}
			StringBuilder sb = new StringBuilder();
			sb.append("[" + algoName + "] #" + info.getId()).append(' ');
			reportSize(info, sb, info.getAllMemoryPools());
			sb.append('\n');
			sb.append("  ");
			Collection<String> eden = info.getEdenPools();
			Collection<String> surv = info.getSurvivourPools();
			Collection<String> old = info.getOldSpacePools();
			Collection<String> perm = info.getPermSpacePools();
			if (!eden.isEmpty()) {
				sb.append("EDEN[");
				reportSize(info, sb, eden);
				sb.append("] ");
			}
			if (!surv.isEmpty()) {
				sb.append("SURVIVOUR[");
				reportSize(info, sb, surv);
				sb.append("] ");
			}
			if (!old.isEmpty()) {
				sb.append("OLD[");
				reportSize(info, sb, old);
				sb.append("] ");
			}
			if (!perm.isEmpty() && info.getSizeBefore(perm) != info.getSizeAfter(perm)) {
				sb.append("PERM[");
				reportSize(info, sb, perm);
				sb.append("] ");
			}
			sb.append('\n');
			
			System.out.print(sb);
		}
	
		public void reportSize(GcReport info, StringBuilder sb, Collection<String> pools) {
			long delta = info.getSizeAfter(pools) - info.getSizeBefore(pools);			
			sb.append(FormatHelper.toMemoryUnits(info.getSizeBefore(pools))).append('B');
			if (delta != 0) {
				sb.append("->")
				.append(FormatHelper.toMemoryUnits(info.getSizeAfter(pools))).append('B');
				if (delta < 0) {
					sb.append(" -").append(FormatHelper.toMemoryUnits(-delta)).append('B');
				}
				else if (delta > 0){
					sb.append(" +").append(FormatHelper.toMemoryUnits(delta)).append('B');
				}
			}
		}
	}
}