management/ThreadMXBean/AllThreadIds.java

/*
 * Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug     4530538
 * @summary Basic unit test of ThreadMXBean.getAllThreadIds()
 * @author  Alexei Guibadoulline and Mandy Chung
 *
 * @key intermittent
 * @modules java.management
 * @run main/othervm AllThreadIds
 */

import java.lang.management.*;
import java.time.Instant;
import java.util.concurrent.Phaser;
import java.util.function.Supplier;

public class AllThreadIds {
    /**
     * A supplier wrapper for the delayed format printing.
     * The supplied value will have to be formatted as <em>$s</em>
     * @param <T> The wrapped type
     */
    private static final class ArgWrapper<T> {
        private final Supplier<T> val;

        public ArgWrapper(Supplier<T> val) {
            this.val = val;
        }

        @Override
        public String toString() {
            T resolved = val.get();
            return resolved != null ? resolved.toString() : null;
        }
    }

    static final int DAEMON_THREADS = 20;
    static final int USER_THREADS = 5;
    static final int ALL_THREADS = DAEMON_THREADS + USER_THREADS;
    private static final boolean live[] = new boolean[ALL_THREADS];
    private static final Thread allThreads[] = new Thread[ALL_THREADS];
    private static final ThreadMXBean mbean = ManagementFactory.getThreadMXBean();
    private static boolean testFailed = false;
    private static boolean trace = false;

    private static long prevTotalThreadCount = 0;
    private static int prevLiveThreadCount = 0;
    private static int prevPeakThreadCount = 0;

    private static final Phaser startupCheck = new Phaser(ALL_THREADS + 1);

    private static void printThreadList() {
        long[] list = mbean.getAllThreadIds();
        for (int i = 1; i <= list.length; i++) {
            System.out.println(i + ": Thread id = " + list[i-1]);
        }
        for (int i = 0; i < ALL_THREADS; i++) {
            Thread t = allThreads[i];
            System.out.println(t.getName() + " Id = " + t.getId() +
                " die = " + live[i] +
                " alive = " + t.isAlive());
        }
    }

    private static void checkInitialState() throws Exception {
        updateCounters();
        checkThreadCount(0, 0);
    }

    private static void checkAllThreadsAlive() throws Exception {
        updateCounters();

        // Start all threads and wait to be sure they all are alive
        for (int i = 0; i < ALL_THREADS; i++) {
            setLive(i, true);
            allThreads[i] = new MyThread(i);
            allThreads[i].setDaemon(i < DAEMON_THREADS);
            allThreads[i].start();
        }
        // wait until all threads are started.
        startupCheck.arriveAndAwaitAdvance();

        checkThreadCount(ALL_THREADS, 0);
        if (trace) {
            printThreadList();
        }
        // Check mbean now. All threads must appear in getAllThreadIds() list
        long[] list = mbean.getAllThreadIds();

        for (int i = 0; i < ALL_THREADS; i++) {
            long expectedId = allThreads[i].getId();
            boolean found = false;

            if (trace) {
                System.out.print("Looking for thread with id " + expectedId);
            }
            for (int j = 0; j < list.length; j++) {
                if (expectedId == list[j]) {
                    found = true;
                    break;
                }
            }

            if (!found) {
                testFailed = true;
            }
            if (trace) {
                if (!found) {
                    System.out.print(". TEST FAILED.");
                }
                System.out.println();
            }
        }
        if (trace) {
            System.out.println();
        }
    }

    private static void checkDaemonThreadsDead() throws Exception {
        updateCounters();

        // Stop daemon threads, wait to be sure they all are dead, and check
        // that they disappeared from getAllThreadIds() list
        for (int i = 0; i < DAEMON_THREADS; i++) {
            setLive(i, false);
        }

        // make sure the daemon threads are completely dead
        joinDaemonThreads();

        // and check the reported thread count
        checkThreadCount(0, DAEMON_THREADS);

        // Check mbean now
        long[] list = mbean.getAllThreadIds();

        for (int i = 0; i < ALL_THREADS; i++) {
            long expectedId = allThreads[i].getId();
            boolean found = false;
            boolean alive = (i >= DAEMON_THREADS);

            if (trace) {
                System.out.print("Looking for thread with id " + expectedId +
                    (alive ? " expected alive." : " expected terminated."));
            }
            for (int j = 0; j < list.length; j++) {
                if (expectedId == list[j]) {
                    found = true;
                    break;
                }
            }

            if (alive != found) {
                testFailed = true;
            }
            if (trace) {
                if (alive != found) {
                    System.out.println(" TEST FAILED.");
                } else {
                    System.out.println();
                }
            }
        }
    }

    private static void checkAllThreadsDead() throws Exception {
        updateCounters();

        // Stop all threads and wait to be sure they all are dead
        for (int i = DAEMON_THREADS; i < ALL_THREADS; i++) {
            setLive(i, false);
        }

        // make sure the non-daemon threads are completely dead
        joinNonDaemonThreads();

        // and check the thread count
        checkThreadCount(0, ALL_THREADS - DAEMON_THREADS);
    }

    private static void checkThreadCount(int numNewThreads,
                                         int numTerminatedThreads)
        throws Exception {

        checkLiveThreads(numNewThreads, numTerminatedThreads);
        checkPeakThreads(numNewThreads);
        checkTotalThreads(numNewThreads);
        checkThreadIds();
    }

    private static void checkLiveThreads(int numNewThreads,
                                         int numTerminatedThreads)
        throws InterruptedException {
        int diff = numNewThreads - numTerminatedThreads;

        waitTillEquals(
            diff + prevLiveThreadCount,
            ()->(long)mbean.getThreadCount(),
            "Unexpected number of live threads: " +
                " Prev live = %1$d Current live = ${provided} Threads added = %2$d" +
                " Threads terminated = %3$d",
            ()->prevLiveThreadCount,
            ()->numNewThreads,
            ()->numTerminatedThreads
        );
    }

    private static void checkPeakThreads(int numNewThreads)
        throws InterruptedException {

        waitTillEquals(numNewThreads + prevPeakThreadCount,
            ()->(long)mbean.getPeakThreadCount(),
            "Unexpected number of peak threads: " +
                " Prev peak = %1$d Current peak = ${provided} Threads added = %2$d",
            ()->prevPeakThreadCount,
            ()->numNewThreads
        );
    }

    private static void checkTotalThreads(int numNewThreads)
        throws InterruptedException {

        waitTillEquals(numNewThreads + prevTotalThreadCount,
            ()->mbean.getTotalStartedThreadCount(),
            "Unexpected number of total threads: " +
                " Prev Total = %1$d Current Total = ${provided} Threads added = %2$d",
            ()->prevTotalThreadCount,
            ()->numNewThreads
        );
    }

    private static void checkThreadIds() throws InterruptedException {
        long[] list = mbean.getAllThreadIds();

        waitTillEquals(
            list.length,
            ()->(long)mbean.getThreadCount(),
            "Array length returned by " +
                "getAllThreadIds() = %1$d not matched count = ${provided}",
            ()->list.length
        );
    }

    /**
     * Waits till the <em>expectedVal</em> equals to the <em>retrievedVal</em>.
     * It will report a status message on the first occasion of the value mismatch
     * and then, subsequently, when the <em>retrievedVal</em> value changes.
     * @param expectedVal The value to wait for
     * @param retrievedVal The supplier of the value to check against the <em>expectedVal</em>
     * @param msgFormat The formatted message to be printed in case of mismatch
     * @param msgArgs The parameters to the formatted message
     * @throws InterruptedException
     */
    private static void waitTillEquals(long expectedVal, Supplier<Long> retrievedVal,
                                        String msgFormat, Supplier<Object> ... msgArgs)
        throws InterruptedException {
        Object[] args = null;

        long countPrev = -1;
        while (true) {
            Long count = retrievedVal.get();
            if (count == expectedVal) break;
            if (countPrev == -1 || countPrev != count) {
                if (args == null) {
                    args = new Object[msgArgs.length];
                    for(int i=0; i < msgArgs.length; i++) {
                        args[i] = new ArgWrapper<>((Supplier<Object>)msgArgs[i]);
                    }
                }
                System.err.format("TS: %s\n", Instant.now());
                System.err.format(
                    msgFormat
                        .replace("${provided}", String.valueOf(count))
                        .replace("$d", "$s"),
                    args
                ).flush();
                printThreadList();
                System.err.println("\nRetrying ...\n");
            }
            countPrev = count;
            Thread.sleep(1);
        }
    }

    private static void updateCounters() {
        prevTotalThreadCount = mbean.getTotalStartedThreadCount();
        prevLiveThreadCount = mbean.getThreadCount();
        prevPeakThreadCount = mbean.getPeakThreadCount();
    }

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

        checkInitialState();
        checkAllThreadsAlive();
        checkDaemonThreadsDead();
        checkAllThreadsDead();

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

        System.out.println("Test passed.");
    }

    private static void joinDaemonThreads() throws InterruptedException {
        for (int i = 0; i < DAEMON_THREADS; i++) {
            allThreads[i].join();
        }
    }

    private static void joinNonDaemonThreads() throws InterruptedException {
        for (int i = DAEMON_THREADS; i < ALL_THREADS; i++) {
            allThreads[i].join();
        }
    }

    private static void setLive(int i, boolean val) {
        synchronized(live) {
            live[i] = val;
        }
    }

    private static boolean isLive(int i) {
        synchronized(live) {
            return live[i];
        }
    }

    // The MyThread thread lives as long as correspondent live[i] value is true
    private static class MyThread extends Thread {
        int id;

        MyThread(int id) {
            this.id = id;
        }

        public void run() {
            // signal started
            startupCheck.arrive();
            while (isLive(id)) {
                try {
                    sleep(100);
                } catch (InterruptedException e) {
                    System.out.println("Unexpected exception is thrown.");
                    e.printStackTrace(System.out);
                    testFailed = true;
                }
            }
        }
    }
}