jdk/test/java/lang/management/MemoryMXBean/LowMemoryTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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/*
 * @test
 * @bug     4530538
 * @summary Basic unit test of memory management testing:
 *          1) setUsageThreshold() and getUsageThreshold()
 *          2) test low memory detection on the old generation.
 * @author  Mandy Chung
 *
 * @requires vm.gc == "null"
 * @requires vm.opt.ExplicitGCInvokesConcurrent != "true"
 * @requires vm.opt.ExplicitGCInvokesConcurrentAndUnloadsClasses != "true"
 * @requires vm.opt.DisableExplicitGC != "true"
 * @library /lib/testlibrary/
 *
 * @build jdk.testlibrary.* LowMemoryTest MemoryUtil RunUtil
 * @run main/timeout=600 LowMemoryTest
 */

import java.lang.management.*;
import java.util.*;
import java.util.concurrent.Phaser;
import javax.management.*;
import javax.management.openmbean.CompositeData;
import jdk.testlibrary.ProcessTools;
import jdk.testlibrary.JDKToolFinder;
import jdk.testlibrary.Utils;

public class LowMemoryTest {
    private static final MemoryMXBean mm = ManagementFactory.getMemoryMXBean();
    private static final List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();
    private static final Phaser phaser = new Phaser(2);
    private static MemoryPoolMXBean mpool = null;
    private static boolean trace = false;
    private static boolean testFailed = false;
    private static final int NUM_TRIGGERS = 5;
    private static final int NUM_CHUNKS = 2;
    private static final int YOUNG_GEN_SIZE = 8 * 1024 * 1024;
    private static long chunkSize;
    private static final String classMain = "LowMemoryTest$TestMain";

    /**
     * Run the test multiple times with different GC versions.
     * First with default command line specified by the framework.
     * Then with GC versions specified by the test.
     */
    public static void main(String a[]) throws Throwable {
        // Use a low young gen size to ensure that the
        // allocated objects are put in the old gen.
        final String nmFlag = "-Xmn" + YOUNG_GEN_SIZE;
        // Using large pages will change the young gen size,
        // make sure we don't use them for this test.
        final String lpFlag = "-XX:-UseLargePages";
        // Prevent G1 from selecting a large heap region size,
        // since that would change the young gen size.
        final String g1Flag = "-XX:G1HeapRegionSize=1m";

        // Runs the test collecting subprocess I/O while it's running.
        traceTest(classMain + ", -XX:+UseSerialGC", nmFlag, lpFlag, "-XX:+UseSerialGC");
        traceTest(classMain + ", -XX:+UseParallelGC", nmFlag, lpFlag, "-XX:+UseParallelGC");
        traceTest(classMain + ", -XX:+UseG1GC", nmFlag, lpFlag, "-XX:+UseG1GC", g1Flag);
        traceTest(classMain + ", -XX:+UseConcMarkSweepGC", nmFlag, lpFlag, "-XX:+UseConcMarkSweepGC");
    }

    /*
     * Creating command-line for running subprocess JVM:
     *
     * JVM command line is like:
     * {test_jdk}/bin/java {defaultopts} -cp {test.class.path} {testopts} main
     *
     * {defaultopts} are the default java options set by the framework.
     *
     * @param testOpts java options specified by the test.
     */
    private static List<String> buildCommandLine(String... testOpts) {
        List<String> opts = new ArrayList<>();
        opts.add(JDKToolFinder.getJDKTool("java"));
        opts.addAll(Arrays.asList(Utils.getTestJavaOpts()));
        opts.add("-cp");
        opts.add(System.getProperty("test.class.path", "test.class.path"));
        opts.add("-Xlog:gc*=debug");
        opts.addAll(Arrays.asList(testOpts));
        opts.add(classMain);

        return opts;
    }

    /**
     * Runs LowMemoryTest$TestMain with the passed options and redirects subprocess
     * standard I/O to the current (parent) process. This provides a trace of what
     * happens in the subprocess while it is runnning (and before it terminates).
     *
     * @param prefixName the prefix string for redirected outputs
     * @param testOpts java options specified by the test.
     */
    private static void traceTest(String prefixName,
                                  String... testOpts)
                throws Throwable {

        // Building command-line
        List<String> opts = buildCommandLine(testOpts);

        // We activate all tracing in subprocess
        opts.add("trace");

        // Launch separate JVM subprocess
        String[] optsArray = opts.toArray(new String[0]);
        ProcessBuilder pb = new ProcessBuilder(optsArray);
        System.out.println("\n========= Tracing of subprocess " + prefixName + " =========");
        Process p = ProcessTools.startProcess(prefixName, pb);

        // Handling end of subprocess
        try {
            int exitCode = p.waitFor();
            if (exitCode != 0) {
                throw new RuntimeException(
                    "Subprocess unexpected exit value of [" + exitCode + "]. Expected 0.\n");
            }
        } catch (InterruptedException e) {
            throw new RuntimeException("Parent process interrupted with exception : \n " + e + " :" );
        }


     }

    private static volatile boolean listenerInvoked = false;
    static class SensorListener implements NotificationListener {
        @Override
        public void handleNotification(Notification notif, Object handback) {
            String type = notif.getType();
            if (type.equals(MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED) ||
                type.equals(MemoryNotificationInfo.
                    MEMORY_COLLECTION_THRESHOLD_EXCEEDED)) {

                MemoryNotificationInfo minfo = MemoryNotificationInfo.
                    from((CompositeData) notif.getUserData());

                MemoryUtil.printMemoryNotificationInfo(minfo, type);
                listenerInvoked = true;
            }
        }
    }

    static class TestListener implements NotificationListener {
        private boolean isRelaxed = false;
        private int triggers = 0;
        private final long[] count = new long[NUM_TRIGGERS * 2];
        private final long[] usedMemory = new long[NUM_TRIGGERS * 2];

        public TestListener() {
            isRelaxed = ManagementFactory.getRuntimeMXBean().getInputArguments().contains("-XX:+UseConcMarkSweepGC");
        }

        @Override
        public void handleNotification(Notification notif, Object handback) {
            MemoryNotificationInfo minfo = MemoryNotificationInfo.
                from((CompositeData) notif.getUserData());
            count[triggers] = minfo.getCount();
            usedMemory[triggers] = minfo.getUsage().getUsed();
            triggers++;
        }
        public void checkResult() throws Exception {
            if (!checkValue(triggers, NUM_TRIGGERS)) {
                throw new RuntimeException("Unexpected number of triggers = " +
                    triggers + " but expected to be " + NUM_TRIGGERS);
            }

            for (int i = 0; i < triggers; i++) {
                if (!checkValue(count[i], i + 1)) {
                    throw new RuntimeException("Unexpected count of" +
                        " notification #" + i +
                        " count = " + count[i] +
                        " but expected to be " + (i+1));
                }
                if (usedMemory[i] < newThreshold) {
                    throw new RuntimeException("Used memory = " +
                        usedMemory[i] + " is less than the threshold = " +
                        newThreshold);
                }
            }
        }

        private boolean checkValue(int value, int target) {
            return checkValue((long)value, target);
        }

        private boolean checkValue(long value, int target) {
            if (!isRelaxed) {
                return value == target;
            } else {
                return value >= target;
            }
        }
    }

    private static long newThreshold;

    private static class TestMain {
        public static void main(String args[]) throws Exception {
            if (args.length > 0 && args[0].equals("trace")) {
                trace = true;
            }

            // Find the Old generation which supports low memory detection
            ListIterator iter = pools.listIterator();
            while (iter.hasNext()) {
                MemoryPoolMXBean p = (MemoryPoolMXBean) iter.next();
                if (p.getType() == MemoryType.HEAP &&
                    p.isUsageThresholdSupported()) {
                    mpool = p;
                    if (trace) {
                        System.out.println("Selected memory pool for low memory " +
                            "detection.");
                        MemoryUtil.printMemoryPool(mpool);
                    }
                    break;
                }
            }

            TestListener listener = new TestListener();
            SensorListener l2 = new SensorListener();
            NotificationEmitter emitter = (NotificationEmitter) mm;
            emitter.addNotificationListener(listener, null, null);
            emitter.addNotificationListener(l2, null, null);

            Thread allocator = new AllocatorThread();
            Thread sweeper = new SweeperThread();

            // The chunk size needs to be larger than YOUNG_GEN_SIZE,
            // otherwise we will get intermittent failures when objects
            // end up in the young gen instead of the old gen.
            final long epsilon = 1024;
            chunkSize = YOUNG_GEN_SIZE + epsilon;

            MemoryUsage mu = mpool.getUsage();
            newThreshold = mu.getUsed() + (chunkSize * NUM_CHUNKS);

            // Sanity check. Make sure the new threshold isn't too large.
            // Tweak the test if this fails.
            final long headRoom = chunkSize * 2;
            final long max = mu.getMax();
            if (max != -1 && newThreshold > max - headRoom) {
                throw new RuntimeException("TEST FAILED: newThreshold: " + newThreshold +
                        " is too near the maximum old gen size: " + max +
                        " used: " + mu.getUsed() + " headRoom: " + headRoom);
            }

            System.out.println("Setting threshold for " + mpool.getName() +
                " from " + mpool.getUsageThreshold() + " to " + newThreshold +
                ".  Current used = " + mu.getUsed());

            mpool.setUsageThreshold(newThreshold);

            if (mpool.getUsageThreshold() != newThreshold) {
                throw new RuntimeException("TEST FAILED: " +
                "Threshold for Memory pool " + mpool.getName() +
                "is " + mpool.getUsageThreshold() + " but expected to be" +
                newThreshold);
            }


            allocator.start();
            // Force Allocator start first
            phaser.arriveAndAwaitAdvance();
            sweeper.start();


            try {
                allocator.join();
                // Wait until AllocatorThread's done
                phaser.arriveAndAwaitAdvance();
                sweeper.join();
            } catch (InterruptedException e) {
                System.out.println("Unexpected exception:" + e);
                testFailed = true;
            }

            listener.checkResult();

            if (testFailed)
                throw new RuntimeException("TEST FAILED.");

            System.out.println(RunUtil.successMessage);
        }
    }

    private static void goSleep(long ms) {
        try {
            Thread.sleep(ms);
        } catch (InterruptedException e) {
            System.out.println("Unexpected exception:" + e);
            testFailed = true;
        }
    }

    private static final List<Object> objectPool = new ArrayList<>();
    static class AllocatorThread extends Thread {
        public void doTask() {
            int iterations = 0;
            int numElements = (int) (chunkSize / 4); // minimal object size
            while (!listenerInvoked || mpool.getUsage().getUsed() < mpool.getUsageThreshold()) {
                iterations++;
                if (trace) {
                    System.out.println("   Iteration " + iterations +
                        ": before allocation " +
                        mpool.getUsage().getUsed());
                }

                Object[] o = new Object[numElements];
                if (iterations <= NUM_CHUNKS) {
                    // only hold a reference to the first NUM_CHUNKS
                    // allocated objects
                    objectPool.add(o);
                }

                if (trace) {
                    System.out.println("               " +
                        "  after allocation " +
                        mpool.getUsage().getUsed());
                }
                goSleep(100);
            }
        }
        @Override
        public void run() {
            for (int i = 1; i <= NUM_TRIGGERS; i++) {
                // Sync with SweeperThread's second phase.
                phaser.arriveAndAwaitAdvance();
                System.out.println("AllocatorThread is doing task " + i +
                    " phase " + phaser.getPhase());
                doTask();
                // Sync with SweeperThread's first phase.
                phaser.arriveAndAwaitAdvance();
                System.out.println("AllocatorThread done task " + i +
                    " phase " + phaser.getPhase());
                if (testFailed) {
                    return;
                }
            }
        }
    }

    static class SweeperThread extends Thread {
        private void doTask() {
            int iterations = 0;
            if (trace) {
                System.out.println("SweeperThread clearing allocated objects.");
            }

            for (; mpool.getUsage().getUsed() >=
                       mpool.getUsageThreshold();) {
                // clear all allocated objects and invoke GC
                objectPool.clear();
                mm.gc();

                if (trace) {
                    iterations++;
                    System.out.println("SweeperThread called " + iterations +
                        " time(s) MemoryMXBean.gc().");
                }

                goSleep(100);
            }
        }

        @Override
        public void run() {
            for (int i = 1; i <= NUM_TRIGGERS; i++) {
                // Sync with AllocatorThread's first phase.
                phaser.arriveAndAwaitAdvance();
                System.out.println("SweeperThread is doing task " + i +
                    " phase " + phaser.getPhase());

                doTask();

                listenerInvoked = false;

                // Sync with AllocatorThread's second phase.
                phaser.arriveAndAwaitAdvance();
                System.out.println("SweeperThread done task " + i +
                    " phase " + phaser.getPhase());
                if (testFailed) return;
            }
        }
    }
}