然后是线程池这块，我们重点注意出现拒绝异常后的处理策略：
@Slf4j public class TomcatThreadPool extends java.util.concurrent.ThreadPoolExecutor { /** * The number of tasks submitted but not yet finished. This includes tasks * in the queue and tasks that have been handed to a worker thread but the * latter did not start executing the task yet. * This number is always greater or equal to {@link #getActiveCount()}. */ private final AtomicInteger submittedCount = new AtomicInteger(0); public TomcatThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) { super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler); prestartAllCoreThreads(); } public TomcatThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler) { super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler); prestartAllCoreThreads(); } public TomcatThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) { super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, new RejectHandler()); prestartAllCoreThreads(); } public TomcatThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) { super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, new RejectHandler()); prestartAllCoreThreads(); } public int getSubmittedCount() { return submittedCount.get(); } /** * {@inheritDoc} */ @Override public void execute(Runnable command) { execute(command, 0, TimeUnit.MILLISECONDS); } /** * Executes the given command at some time in the future. The command * may execute in a new thread, in a pooled thread, or in the calling * thread, at the discretion of the <tt>Executor</tt> implementation. * If no threads are available, it will be added to the work queue. * If the work queue is full, the system will wait for the specified * time and it throw a RejectedExecutionException if the queue is still * full after that. * * @param command the runnable task * @param timeout A timeout for the completion of the task * @param unit The timeout time unit * @throws RejectedExecutionException if this task cannot be * accepted for execution - the queue is full * @throws NullPointerException if command or unit is null */ public void execute(Runnable command, long timeout, TimeUnit unit) { submittedCount.incrementAndGet(); try { super.execute(command); } catch (RejectedExecutionException rx) { if (super.getQueue() instanceof TomcatTaskQueue) { final TomcatTaskQueue queue = (TomcatTaskQueue) super.getQueue(); try { if (!queue.force(command, timeout, unit)) { submittedCount.decrementAndGet(); throw new RejectedExecutionException("threadPoolExecutor.queueFull"); } else { log.warn("RejectedExecutionException throw, task {} put into queue again", command.toString()); } } catch (InterruptedException x) { submittedCount.decrementAndGet(); throw new RejectedExecutionException(x); } } else { submittedCount.decrementAndGet(); throw rx; } } } private static class RejectHandler implements RejectedExecutionHandler { @Override public void rejectedExecution(Runnable r, java.util.concurrent.ThreadPoolExecutor executor) { throw new RejectedExecutionException(); } } }