feat: 创建自定义线程池实现拒绝策略统计次数.

3 years ago · ed17f48ddf
parent 82256ea5e7
commit ed17f48ddf
1 changed files with 985 additions and 0 deletions
--- a/dynamic-threadpool-spring-boot-starter/src/main/java/io/dynamic/threadpool/starter/wrap/CustomThreadPoolExecutor.java
+++ b/dynamic-threadpool-spring-boot-starter/src/main/java/io/dynamic/threadpool/starter/wrap/CustomThreadPoolExecutor.java
@ -0,0 +1,985 @@
 package io.dynamic.threadpool.starter.wrap;
 import lombok.Getter;
 import java.security.AccessControlContext;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
 import java.util.*;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.locks.AbstractQueuedSynchronizer;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
 /**
 * Custom Thread Pool Wrap.
 *
 * @author chen.ma
 * @date 2021/7/8 21:47
 */
@Getter
 public final class CustomThreadPoolExecutor extends ThreadPoolExecutor {
    private final AtomicInteger regectCount = new AtomicInteger();
    private final AtomicInteger ctl = new AtomicInteger(ctlOf(RUNNING, 0));
    private static final int COUNT_BITS = Integer.SIZE - 3;
    private static final int CAPACITY = (1 << COUNT_BITS) - 1;
    private static final int RUNNING = -1 << COUNT_BITS;
    private static final int SHUTDOWN = 0 << COUNT_BITS;
    private static final int STOP = 1 << COUNT_BITS;
    private static final int TIDYING = 2 << COUNT_BITS;
    private static final int TERMINATED = 3 << COUNT_BITS;
    private static int runStateOf(int c) {
        return c & ~CAPACITY;
    }
    private static int workerCountOf(int c) {
        return c & CAPACITY;
    }
    private static int ctlOf(int rs, int wc) {
        return rs | wc;
    }
    private static boolean runStateLessThan(int c, int s) {
        return c < s;
    }
    private static boolean runStateAtLeast(int c, int s) {
        return c >= s;
    }
    private static boolean isRunning(int c) {
        return c < SHUTDOWN;
    }
    private boolean compareAndIncrementWorkerCount(int expect) {
        return ctl.compareAndSet(expect, expect + 1);
    }
    private boolean compareAndDecrementWorkerCount(int expect) {
        return ctl.compareAndSet(expect, expect - 1);
    }
    private void decrementWorkerCount() {
        do {
        } while (!compareAndDecrementWorkerCount(ctl.get()));
    }
    public Integer getRegectCount() {
        return regectCount.get();
    }
    private final BlockingQueue<Runnable> workQueue;
    private final ReentrantLock mainLock = new ReentrantLock();
    private final HashSet<Worker> workers = new HashSet();
    private final Condition termination = mainLock.newCondition();
    private int largestPoolSize;
    private long completedTaskCount;
    private volatile ThreadFactory threadFactory;
    private volatile RejectedExecutionHandler handler;
    private volatile long keepAliveTime;
    private volatile boolean allowCoreThreadTimeOut;
    private volatile int corePoolSize;
    private volatile int maximumPoolSize;
    private static final RejectedExecutionHandler defaultHandler =
            new ThreadPoolExecutor.AbortPolicy();
    private static final RuntimePermission shutdownPerm =
            new RuntimePermission("modifyThread");
    private final AccessControlContext acc;
    private final class Worker
            extends AbstractQueuedSynchronizer
            implements Runnable {
        private static final long serialVersionUID = 6138294804551838833L;
        final Thread thread;
        Runnable firstTask;
        volatile long completedTasks;
        Worker(Runnable firstTask) {
            setState(-1); // inhibit interrupts until runWorker
            this.firstTask = firstTask;
            this.thread = getThreadFactory().newThread(this);
        }
        @Override
        public void run() {
            runWorker(this);
        }
        @Override
        protected boolean isHeldExclusively() {
            return getState() != 0;
        }
        @Override
        protected boolean tryAcquire(int unused) {
            if (compareAndSetState(0, 1)) {
                setExclusiveOwnerThread(Thread.currentThread());
                return true;
            }
            return false;
        }
        @Override
        protected boolean tryRelease(int unused) {
            setExclusiveOwnerThread(null);
            setState(0);
            return true;
        }
        public void lock() {
            acquire(1);
        }
        public boolean tryLock() {
            return tryAcquire(1);
        }
        public void unlock() {
            release(1);
        }
        public boolean isLocked() {
            return isHeldExclusively();
        }
        void interruptIfStarted() {
            Thread t;
            if (getState() >= 0 && (t = thread) != null && !t.isInterrupted()) {
                try {
                    t.interrupt();
                } catch (SecurityException ignore) {
                }
            }
        }
    }
    private void advanceRunState(int targetState) {
        for (; ; ) {
            int c = ctl.get();
            if (runStateAtLeast(c, targetState) ||
                    ctl.compareAndSet(c, ctlOf(targetState, workerCountOf(c)))) {
                break;
            }
        }
    }
    final void tryTerminate() {
        for (; ; ) {
            int c = ctl.get();
            if (isRunning(c) ||
                    runStateAtLeast(c, TIDYING) ||
                    (runStateOf(c) == SHUTDOWN && !workQueue.isEmpty())) {
                return;
            }
            if (workerCountOf(c) != 0) {
                interruptIdleWorkers(ONLY_ONE);
                return;
            }
            final ReentrantLock mainLock = this.mainLock;
            mainLock.lock();
            try {
                if (ctl.compareAndSet(c, ctlOf(TIDYING, 0))) {
                    try {
                        terminated();
                    } finally {
                        ctl.set(ctlOf(TERMINATED, 0));
                        termination.signalAll();
                    }
                    return;
                }
            } finally {
                mainLock.unlock();
            }
        }
    }
    private void checkShutdownAccess() {
        SecurityManager security = System.getSecurityManager();
        if (security != null) {
            security.checkPermission(shutdownPerm);
            final ReentrantLock mainLock = this.mainLock;
            mainLock.lock();
            try {
                for (Worker w : workers) {
                    security.checkAccess(w.thread);
                }
            } finally {
                mainLock.unlock();
            }
        }
    }
    private void interruptWorkers() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            for (Worker w : workers) {
                w.interruptIfStarted();
            }
        } finally {
            mainLock.unlock();
        }
    }
    private void interruptIdleWorkers(boolean onlyOne) {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            for (Worker w : workers) {
                Thread t = w.thread;
                if (!t.isInterrupted() && w.tryLock()) {
                    try {
                        t.interrupt();
                    } catch (SecurityException ignore) {
                    } finally {
                        w.unlock();
                    }
                }
                if (onlyOne) {
                    break;
                }
            }
        } finally {
            mainLock.unlock();
        }
    }
    private void interruptIdleWorkers() {
        interruptIdleWorkers(false);
    }
    private static final boolean ONLY_ONE = true;
    final void reject(Runnable command) {
        regectCount.incrementAndGet();
        handler.rejectedExecution(command, this);
    }
    void onShutdown() {
    }
    final boolean isRunningOrShutdown(boolean shutdownOK) {
        int rs = runStateOf(ctl.get());
        return rs == RUNNING || (rs == SHUTDOWN && shutdownOK);
    }
    private List<Runnable> drainQueue() {
        BlockingQueue<Runnable> q = workQueue;
        ArrayList<Runnable> taskList = new ArrayList<Runnable>();
        q.drainTo(taskList);
        if (!q.isEmpty()) {
            for (Runnable r : q.toArray(new Runnable[0])) {
                if (q.remove(r)) {
                    taskList.add(r);
                }
            }
        }
        return taskList;
    }
    private boolean addWorker(Runnable firstTask, boolean core) {
        retry:
        for (; ; ) {
            int c = ctl.get();
            int rs = runStateOf(c);
            // Check if queue empty only if necessary.
            if (rs >= SHUTDOWN &&
                    !(rs == SHUTDOWN &&
                            firstTask == null &&
                            !workQueue.isEmpty())) {
                return false;
            }
            for (; ; ) {
                int wc = workerCountOf(c);
                if (wc >= CAPACITY ||
                        wc >= (core ? corePoolSize : maximumPoolSize)) {
                    return false;
                }
                if (compareAndIncrementWorkerCount(c)) {
                    break retry;
                }
                c = ctl.get();
                if (runStateOf(c) != rs) {
                    continue retry;
                }
            }
        }
        boolean workerStarted = false;
        boolean workerAdded = false;
        Worker w = null;
        try {
            w = new Worker(firstTask);
            final Thread t = w.thread;
            if (t != null) {
                final ReentrantLock mainLock = this.mainLock;
                mainLock.lock();
                try {
                    int rs = runStateOf(ctl.get());
                    if (rs < SHUTDOWN ||
                            (rs == SHUTDOWN && firstTask == null)) {
                        if (t.isAlive()) {
                            throw new IllegalThreadStateException();
                        }
                        workers.add(w);
                        int s = workers.size();
                        if (s > largestPoolSize) {
                            largestPoolSize = s;
                        }
                        workerAdded = true;
                    }
                } finally {
                    mainLock.unlock();
                }
                if (workerAdded) {
                    t.start();
                    workerStarted = true;
                }
            }
        } finally {
            if (!workerStarted) {
                addWorkerFailed(w);
            }
        }
        return workerStarted;
    }
    private void addWorkerFailed(Worker w) {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            if (w != null) {
                workers.remove(w);
            }
            decrementWorkerCount();
            tryTerminate();
        } finally {
            mainLock.unlock();
        }
    }
    private void processWorkerExit(Worker w, boolean completedAbruptly) {
        if (completedAbruptly) {
            decrementWorkerCount();
        }
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            completedTaskCount += w.completedTasks;
            workers.remove(w);
        } finally {
            mainLock.unlock();
        }
        tryTerminate();
        int c = ctl.get();
        if (runStateLessThan(c, STOP)) {
            if (!completedAbruptly) {
                int min = allowCoreThreadTimeOut ? 0 : corePoolSize;
                if (min == 0 && !workQueue.isEmpty()) {
                    min = 1;
                }
                if (workerCountOf(c) >= min) {
                    return; // replacement not needed
                }
            }
            addWorker(null, false);
        }
    }
    private Runnable getTask() {
        boolean timedOut = false;
        for (; ; ) {
            int c = ctl.get();
            int rs = runStateOf(c);
            if (rs >= SHUTDOWN && (rs >= STOP || workQueue.isEmpty())) {
                decrementWorkerCount();
                return null;
            }
            int wc = workerCountOf(c);
            boolean timed = allowCoreThreadTimeOut || wc > corePoolSize;
            if ((wc > maximumPoolSize || (timed && timedOut))
                    && (wc > 1 || workQueue.isEmpty())) {
                if (compareAndDecrementWorkerCount(c)) {
                    return null;
                }
                continue;
            }
            try {
                Runnable r = timed ?
                        workQueue.poll(keepAliveTime, TimeUnit.NANOSECONDS) :
                        workQueue.take();
                if (r != null) {
                    return r;
                }
                timedOut = true;
            } catch (InterruptedException retry) {
                timedOut = false;
            }
        }
    }
    final void runWorker(Worker w) {
        Thread wt = Thread.currentThread();
        Runnable task = w.firstTask;
        w.firstTask = null;
        w.unlock();
        boolean completedAbruptly = true;
        try {
            while (task != null || (task = getTask()) != null) {
                w.lock();
                if ((runStateAtLeast(ctl.get(), STOP) ||
                        (Thread.interrupted() &&
                                runStateAtLeast(ctl.get(), STOP))) &&
                        !wt.isInterrupted()) {
                    wt.interrupt();
                }
                try {
                    beforeExecute(wt, task);
                    Throwable thrown = null;
                    try {
                        task.run();
                    } catch (RuntimeException x) {
                        thrown = x;
                        throw x;
                    } catch (Error x) {
                        thrown = x;
                        throw x;
                    } catch (Throwable x) {
                        thrown = x;
                        throw new Error(x);
                    } finally {
                        afterExecute(task, thrown);
                    }
                } finally {
                    task = null;
                    w.completedTasks++;
                    w.unlock();
                }
            }
            completedAbruptly = false;
        } finally {
            processWorkerExit(w, completedAbruptly);
        }
    }
    public CustomThreadPoolExecutor(int corePoolSize,
                                    int maximumPoolSize,
                                    long keepAliveTime,
                                    TimeUnit unit,
                                    BlockingQueue<Runnable> workQueue) {
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
                Executors.defaultThreadFactory(), defaultHandler);
    }
    public CustomThreadPoolExecutor(int corePoolSize,
                                    int maximumPoolSize,
                                    long keepAliveTime,
                                    TimeUnit unit,
                                    BlockingQueue<Runnable> workQueue,
                                    ThreadFactory threadFactory) {
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
                threadFactory, defaultHandler);
    }
    public CustomThreadPoolExecutor(int corePoolSize,
                                    int maximumPoolSize,
                                    long keepAliveTime,
                                    TimeUnit unit,
                                    BlockingQueue<Runnable> workQueue,
                                    RejectedExecutionHandler handler) {
        this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,
                Executors.defaultThreadFactory(), handler);
    }
    public CustomThreadPoolExecutor(int corePoolSize,
                                    int maximumPoolSize,
                                    long keepAliveTime,
                                    TimeUnit unit,
                                    BlockingQueue<Runnable> workQueue,
                                    ThreadFactory threadFactory,
                                    RejectedExecutionHandler handler) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
        if (corePoolSize < 0 ||
                maximumPoolSize <= 0 ||
                maximumPoolSize < corePoolSize ||
                keepAliveTime < 0) {
            throw new IllegalArgumentException();
        }
        if (workQueue == null || threadFactory == null || handler == null) {
            throw new NullPointerException();
        }
        this.acc = System.getSecurityManager() == null ?
                null :
                AccessController.getContext();
        this.corePoolSize = corePoolSize;
        this.maximumPoolSize = maximumPoolSize;
        this.workQueue = workQueue;
        this.keepAliveTime = unit.toNanos(keepAliveTime);
        this.threadFactory = threadFactory;
        this.handler = handler;
    }
    @Override
    public void execute(Runnable command) {
        if (command == null) {
            throw new NullPointerException();
        }
        int c = ctl.get();
        if (workerCountOf(c) < corePoolSize) {
            if (addWorker(command, true)) {
                return;
            }
            c = ctl.get();
        }
        if (isRunning(c) && workQueue.offer(command)) {
            int recheck = ctl.get();
            if (!isRunning(recheck) && remove(command)) {
                reject(command);
            } else if (workerCountOf(recheck) == 0) {
                addWorker(null, false);
            }
        } else if (!addWorker(command, false)) {
            reject(command);
        }
    }
    @Override
    public void shutdown() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            checkShutdownAccess();
            advanceRunState(SHUTDOWN);
            interruptIdleWorkers();
            onShutdown();
        } finally {
            mainLock.unlock();
        }
        tryTerminate();
    }
    @Override
    public List<Runnable> shutdownNow() {
        List<Runnable> tasks;
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            checkShutdownAccess();
            advanceRunState(STOP);
            interruptWorkers();
            tasks = drainQueue();
        } finally {
            mainLock.unlock();
        }
        tryTerminate();
        return tasks;
    }
    @Override
    public boolean isShutdown() {
        return !isRunning(ctl.get());
    }
    @Override
    public boolean isTerminating() {
        int c = ctl.get();
        return !isRunning(c) && runStateLessThan(c, TERMINATED);
    }
    @Override
    public boolean isTerminated() {
        return runStateAtLeast(ctl.get(), TERMINATED);
    }
    @Override
    public boolean awaitTermination(long timeout, TimeUnit unit)
            throws InterruptedException {
        long nanos = unit.toNanos(timeout);
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            for (; ; ) {
                if (runStateAtLeast(ctl.get(), TERMINATED)) {
                    return true;
                }
                if (nanos <= 0) {
                    return false;
                }
                nanos = termination.awaitNanos(nanos);
            }
        } finally {
            mainLock.unlock();
        }
    }
    @Override
    protected void finalize() {
        SecurityManager sm = System.getSecurityManager();
        if (sm == null || acc == null) {
            shutdown();
        } else {
            PrivilegedAction<Void> pa = () -> {
                shutdown();
                return null;
            };
            AccessController.doPrivileged(pa, acc);
        }
    }
    @Override
    public void setThreadFactory(ThreadFactory threadFactory) {
        if (threadFactory == null) {
            throw new NullPointerException();
        }
        this.threadFactory = threadFactory;
    }
    @Override
    public ThreadFactory getThreadFactory() {
        return threadFactory;
    }
    @Override
    public void setRejectedExecutionHandler(RejectedExecutionHandler handler) {
        if (handler == null) {
            throw new NullPointerException();
        }
        this.handler = handler;
    }
    @Override
    public RejectedExecutionHandler getRejectedExecutionHandler() {
        return handler;
    }
    @Override
    public void setCorePoolSize(int corePoolSize) {
        if (corePoolSize < 0) {
            throw new IllegalArgumentException();
        }
        int delta = corePoolSize - this.corePoolSize;
        this.corePoolSize = corePoolSize;
        if (workerCountOf(ctl.get()) > corePoolSize) {
            interruptIdleWorkers();
        } else if (delta > 0) {
            int k = Math.min(delta, workQueue.size());
            while (k-- > 0 && addWorker(null, true)) {
                if (workQueue.isEmpty()) {
                    break;
                }
            }
        }
    }
    @Override
    public int getCorePoolSize() {
        return corePoolSize;
    }
    @Override
    public boolean prestartCoreThread() {
        return workerCountOf(ctl.get()) < corePoolSize &&
                addWorker(null, true);
    }
    @Override
    public int prestartAllCoreThreads() {
        int n = 0;
        while (addWorker(null, true)) {
            ++n;
        }
        return n;
    }
    @Override
    public boolean allowsCoreThreadTimeOut() {
        return allowCoreThreadTimeOut;
    }
    @Override
    public void allowCoreThreadTimeOut(boolean value) {
        if (value && keepAliveTime <= 0) {
            throw new IllegalArgumentException("Core threads must have nonzero keep alive times");
        }
        if (value != allowCoreThreadTimeOut) {
            allowCoreThreadTimeOut = value;
            if (value) {
                interruptIdleWorkers();
            }
        }
    }
    @Override
    public void setMaximumPoolSize(int maximumPoolSize) {
        if (maximumPoolSize <= 0 || maximumPoolSize < corePoolSize) {
            throw new IllegalArgumentException();
        }
        this.maximumPoolSize = maximumPoolSize;
        if (workerCountOf(ctl.get()) > maximumPoolSize) {
            interruptIdleWorkers();
        }
    }
    @Override
    public int getMaximumPoolSize() {
        return maximumPoolSize;
    }
    @Override
    public void setKeepAliveTime(long time, TimeUnit unit) {
        if (time < 0) {
            throw new IllegalArgumentException();
        }
        if (time == 0 && allowsCoreThreadTimeOut()) {
            throw new IllegalArgumentException("Core threads must have nonzero keep alive times");
        }
        long keepAliveTime = unit.toNanos(time);
        long delta = keepAliveTime - this.keepAliveTime;
        this.keepAliveTime = keepAliveTime;
        if (delta < 0) {
            interruptIdleWorkers();
        }
    }
    @Override
    public long getKeepAliveTime(TimeUnit unit) {
        return unit.convert(keepAliveTime, TimeUnit.NANOSECONDS);
    }
    @Override
    public BlockingQueue<Runnable> getQueue() {
        return workQueue;
    }
    @Override
    public boolean remove(Runnable task) {
        boolean removed = workQueue.remove(task);
        tryTerminate();
        return removed;
    }
    @Override
    public void purge() {
        final BlockingQueue<Runnable> q = workQueue;
        try {
            Iterator<Runnable> it = q.iterator();
            while (it.hasNext()) {
                Runnable r = it.next();
                if (r instanceof Future<?> && ((Future<?>) r).isCancelled()) {
                    it.remove();
                }
            }
        } catch (ConcurrentModificationException fallThrough) {
            for (Object r : q.toArray()) {
                if (r instanceof Future<?> && ((Future<?>) r).isCancelled()) {
                    q.remove(r);
                }
            }
        }
        tryTerminate();
    }
    @Override
    public int getPoolSize() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            return runStateAtLeast(ctl.get(), TIDYING) ? 0
                    : workers.size();
        } finally {
            mainLock.unlock();
        }
    }
    @Override
    public int getActiveCount() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            int n = 0;
            for (Worker w : workers) {
                if (w.isLocked()) {
                    ++n;
                }
            }
            return n;
        } finally {
            mainLock.unlock();
        }
    }
    @Override
    public int getLargestPoolSize() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            return largestPoolSize;
        } finally {
            mainLock.unlock();
        }
    }
    @Override
    public long getTaskCount() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            long n = completedTaskCount;
            for (Worker w : workers) {
                n += w.completedTasks;
                if (w.isLocked()) {
                    ++n;
                }
            }
            return n + workQueue.size();
        } finally {
            mainLock.unlock();
        }
    }
    @Override
    public long getCompletedTaskCount() {
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            long n = completedTaskCount;
            for (Worker w : workers) {
                n += w.completedTasks;
            }
            return n;
        } finally {
            mainLock.unlock();
        }
    }
    @Override
    public String toString() {
        long ncompleted;
        int nworkers, nactive;
        final ReentrantLock mainLock = this.mainLock;
        mainLock.lock();
        try {
            ncompleted = completedTaskCount;
            nactive = 0;
            nworkers = workers.size();
            for (Worker w : workers) {
                ncompleted += w.completedTasks;
                if (w.isLocked()) {
                    ++nactive;
                }
            }
        } finally {
            mainLock.unlock();
        }
        int c = ctl.get();
        String rs = (runStateLessThan(c, SHUTDOWN) ? "Running" :
                (runStateAtLeast(c, TERMINATED) ? "Terminated" :
                        "Shutting down"));
        return super.toString() +
                "[" + rs +
                ", pool size = " + nworkers +
                ", active threads = " + nactive +
                ", queued tasks = " + workQueue.size() +
                ", completed tasks = " + ncompleted +
                "]";
    }
    @Override
    protected void beforeExecute(Thread t, Runnable r) {
    }
    @Override
    protected void afterExecute(Runnable r, Throwable t) {
    }
    @Override
    protected void terminated() {
    }
    public static class CallerRunsPolicy implements RejectedExecutionHandler {
        public CallerRunsPolicy() {
        }
        @Override
        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
            if (!e.isShutdown()) {
                r.run();
            }
        }
    }
    public static class AbortPolicy implements RejectedExecutionHandler {
        public AbortPolicy() {
        }
        @Override
        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
            throw new RejectedExecutionException("Task " + r.toString() +
                    " rejected from " +
                    e.toString());
        }
    }
    public static class DiscardPolicy implements RejectedExecutionHandler {
        public DiscardPolicy() {
        }
        @Override
        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
        }
    }
    public static class DiscardOldestPolicy implements RejectedExecutionHandler {
        public DiscardOldestPolicy() {
        }
        @Override
        public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
            if (!e.isShutdown()) {
                e.getQueue().poll();
                e.execute(r);
            }
        }
    }
 }