* Copyright (c) 2013, 2014 Oracle and/or its affiliates. All rights reserved.

 *          and leads to data corruption. Run this test manually (as

 *          an ordinary java program) with  -Xmx8M  to repro bug 8024521.

 * @run main/othervm -Xmx8M -Dtest.duration=2 CloseRace

    private static final String BIG_FILE = "bigfile";

    private static final int[] procFDs = new int[6];

    /** default value sufficient to repro bug 8024521. */

    private static final int testDurationSeconds

        = Integer.getInteger("test.duration", 600);

    static boolean fdInUse(int i) {

        return new File("/proc/self/fd/" + i).exists();

    }

    static boolean[] procFDsInUse() {

        boolean[] inUse = new boolean[procFDs.length];

        for (int i = 0; i < procFDs.length; i++)

            inUse[i] = fdInUse(procFDs[i]);

        return inUse;

    }

    static int count(boolean[] bits) {

        int count = 0;

        for (int i = 0; i < bits.length; i++)

            count += bits[i] ? 1 : 0;

        return count;

    public static void main(String args[]) throws Exception {

        if (!(new File("/proc/self/fd").isDirectory()))

            return;

        // Catch Errors from process reaper

        Thread.setDefaultUncaughtExceptionHandler

            ((t, e) -> { e.printStackTrace(); System.exit(1); });

        try (RandomAccessFile f = new RandomAccessFile(BIG_FILE, "rw")) {

            f.setLength(Runtime.getRuntime().maxMemory()); // provoke OOME

        for (int i = 0, j = 0; j < procFDs.length; i++)

            if (!fdInUse(i))

                procFDs[j++] = i;

        Thread[] threads = {

            new Thread(new OpenLoop()),

            new Thread(new ExecLoop()),

        };

        for (Thread thread : threads)

            thread.start();

        Thread.sleep(testDurationSeconds * 1000);

        for (Thread thread : threads)

            thread.interrupt();

        for (Thread thread : threads)

            thread.join();

    }

    static class OpenLoop implements Runnable {

        public void run() {

            while (!Thread.interrupted()) {

                try {

                    // wait for ExecLoop to finish creating process

                    do {} while (count(procFDsInUse()) != 3);

                    List<InputStream> iss = new ArrayList<>(4);

                    // eat up three "holes" (closed ends of pipe fd pairs)

                    for (int i = 0; i < 3; i++)

                        iss.add(new FileInputStream(BIG_FILE));

                    do {} while (count(procFDsInUse()) == procFDs.length);

                    // hopefully this will racily occupy empty fd slot

                    iss.add(new FileInputStream(BIG_FILE));

                    Thread.sleep(1); // Widen race window

                    for (InputStream is : iss)

                        is.close();

                } catch (InterruptedException e) {

                    break;

                } catch (Exception e) {

                    throw new Error(e);

    }

    static class ExecLoop implements Runnable {

        public void run() {

            ProcessBuilder builder = new ProcessBuilder("/bin/true");

            while (!Thread.interrupted()) {

                try {

                    // wait for OpenLoop to finish

                    do {} while (count(procFDsInUse()) > 0);

                    Process process = builder.start();

                    InputStream is = process.getInputStream();

                    process.waitFor();

                    is.close();

                } catch (InterruptedException e) {

                    break;

                } catch (Exception e) {

                    throw new Error(e);