MemoryObserver.java

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package org.matsim.utils;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.concurrent.atomic.AtomicBoolean;

public class MemoryObserver {

    private final static Logger LOG = LogManager.getLogger(MemoryObserver.class);

    private static Thread thread = null;
    private static MemoryPrinter runnable = null;

    public static void start(int interval_seconds) {
        startMillis(interval_seconds * 1000L);
    }

    static void startMillis(long interval) {
        stop();

        runnable = new MemoryPrinter(interval);
        thread = new Thread(runnable, "MemoryPrinter");
        thread.setDaemon(true);
        thread.start();
    }

    public static void stop() {
        if (thread != null) {
            runnable.stopFlag.set(true);
            thread.interrupt();
        }
    }

    public static void printMemory() {
        long totalMem = Runtime.getRuntime().totalMemory();
        long freeMem = Runtime.getRuntime().freeMemory();
        long usedMem = totalMem - freeMem;
        LOG.info("used RAM: " + (usedMem/1024/1024) + " MB  free: " + (freeMem/1024/1024) + " MB  total: " + (totalMem/1024/1024) + " MB");
    }

    private static class MemoryPrinter implements Runnable {

        private final long millis;
        private final AtomicBoolean stopFlag = new AtomicBoolean(false);

        private MemoryPrinter(long millis) {
            this.millis = millis;
        }

        public void run() {
            while (true) {
                MemoryObserver.printMemory();

                try {
                    Thread.sleep(this.millis);
                } catch (InterruptedException e) {
                    if (this.stopFlag.get()) {
                        return;
                    }
                    e.printStackTrace();
                }
            }
        }

    }


}