RejectedExecutionException

2024-05-13 23:38

本文主要是介绍RejectedExecutionException,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!



ThreadPoolExecutor

一个ExecutorService,它使用可能的几个线程池之一执行每个提交的任务,通常使用Executors工厂方法配置,但是查看源码,发现工厂方法也是统一调用了ThreadPoolExecutor类,以为例,源码如下:
public class Executors {public static ExecutorService newFixedThreadPool(int nThreads) {return new ThreadPoolExecutor(nThreads, nThreads,0L, TimeUnit.MILLISECONDS,new LinkedBlockingQueue<Runnable>());}public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {return new ThreadPoolExecutor(nThreads, nThreads,0L, TimeUnit.MILLISECONDS,new LinkedBlockingQueue<Runnable>(),threadFactory);}
}
虽然我一直认同 程序员应使用较为方便的Executors工厂方法Executors.newCachedThreadPool() (无界线程池,可以进行自动线程回收)、Executors.newFixedThreadPool(int)(固定大小线程池)和Executors.newSingleThreadExecutor()(单个后台线程),但是通过 源码我们可以发现最后他们均调用了ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) 方法,因此我们在分析java.util.concurrent.RejectedExecutionException之前,需要深入学习一下ThreadPoolExecutor的使用。

核心池和最大池的大小

TreadPoolExecutor将根据corePoolSize和maximumPoolSize设置的边界自动调整池大小。当新任务在方法execute(java.lang.Runnable)中提交时,如果运行的线程少于corePoolSize,则创建新线程来处理请求,即使其他辅助线程是空闲的。如果运行的线程多于corePoolSize而少于maximumPoolSize,则仅当队列满时才创建新的线程。如果设置的corePoolSize和maximumPoolSize相同,则创建了固定大小的线程池。如果将maximumPoolSize设置为基本的无界值(如Integer.MAX_VALUE),则允许线程池适应任意数量的并发任务。

保持活动时间

如果池中当前有多于corePoolSize的线程,则这些多出的线程在空闲时间超过keepAliveTime时将会终止。

排队

所有BlockingQueue都可用于传输和保持提交的任务。可以使用此队列与池大小进行交互:
  • 如果运行的线程少于corePoolSize,则Executor始终首选添加新的线程,而不进行排队。
  • 如果运行的线程等于或多于corePoolSize,则Executor始终首选将请求加入队列,而不添加新的线程。
  • 如果无法将请求加入队列,则创建新的线程,除非创建此线程超出maximumPoolSize,在这种情况下,任务将被拒绝(抛出RejectedExecutionException)
排队有三种通用策略:
  1. 直接提交。工作队列的默认选项是synchronousQueue,它将任务直接提交给线程而不保持它们。在此,如果不存在可用于立即运行任务的线程,则试图把任务加入队列将失败,因此会构造一个新的线程。此策略可以避免在处理可能具有内部依赖性的请求集时出现锁。直接提交通常要求无界maximumPoolSizes以避免拒绝新提交的任务。当命令以超过队列所能处理的平均数连续到达时,此策略允许无界线程具有增加的可能性。
  2. 无界队列。使用无界队列(例如,不具有预定义容量的LinkedBlockingQueue)将导致在所有corePoolSize线程都忙时新任务在队列中等待。这样,创建的线程就不会超过corePoolSize(因此,maximumPoolSize的值也就无效了)。
  3. 有界队列。当使用有限的maximumPoolSizes时,有界队列(如ArrayBlockingQueue)有助于防止资源耗尽,但是可能较难调整和控制。队列大小和最大池大小可能需要相互折衷:使用大型队列和小型池可以最大限度的降低CPU使用率、操作系统资源和上下文切换开销,但是可能导致人工降低吞吐量。如果任务频繁阻塞,则系统可能为超过您许可的更多线程安排时间,使用小型队列通常要求较大的池大小,CPU使用率较高,但是可能遇到不可接受的调度开销,这样可会降低吞吐量。

终止

程序不再引用的池没有剩余线程会自动shutdown。如果希望确保回收取消引用的池(即使用户忘记调用shutdown()),则必须安排未使用的线程最终终止。

分析

通过对ThreadPoolExecutor类分析,引发java.util.concurrent.RejectedExecutionException主要有两种原因:
1. 线程池显示的调用了shutdown()之后,再向线程池提交任务的时候,如果你配置的拒绝策略是ThreadPoolExecutor.AbortPolicy的话,这个异常就被会抛出来。
2. 当你的排队策略为有界队列,并且配置的拒绝策略是ThreadPoolExecutor.AbortPolicy,当线程池的线程数量已经达到了maximumPoolSize的时候,你再向它提交任务,就会抛出ThreadPoolExecutor.AbortPolicy异常。

显示关闭掉线程池

这一点很好理解。比如说,你向一个 仓库去存放货物,一开始,仓库管理员把门给你打开了,你放了第一件商品到仓库里,但是当你放好出去后,有人把仓库门关了,那你下次再来存放物品时,你就会被拒绝。示例代码如下:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class TextExecutor {public ExecutorService fixedExecutorService = Executors.newFixedThreadPool(5);public ExecutorService cachedExecutorService = Executors.newCachedThreadPool();public ExecutorService singleExecutorService = Executors.newSingleThreadExecutor();public void testExecutorException() {for (int i = 0; i < 10; i ++) {fixedExecutorService.execute(new SayHelloRunnable());fixedExecutorService.shutdown();}}private class SayHelloRunnable implements Runnable {@Overridepublic void run() {try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch <span id="5_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="5_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=block&k0=block&kdi0=0&luki=7&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="5" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">block</span></a></span>e.printStackTrace();} finally {System.out.println("hello world!");}}}public static void main(String[] args) {TextExecutor testExecutor = new TextExecutor();testExecutor.testExecutorException();}
}

解决方案

1. 不要显示的调用shutdown方法,例如Android里,只有你在Destory方法里cancel掉AsyncTask,则线程池里没有活跃线程会自己回收自己。
2. 调用线程池时,判断是否已经shutdown,通过API方法isShutDown方法判断,示例代码:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class TextExecutor {public ExecutorService fixedExecutorService = Executors.newFixedThreadPool(5);public ExecutorService cachedExecutorService = Executors.newCachedThreadPool();public ExecutorService singleExecutorService = Executors.newSingleThreadExecutor();public void testExecutorException() {for (int i = 0; i < 10; i ++) {// 增加isShutdown()判断if (!fixedExecutorService.isShutdown()) {fixedExecutorService.execute(new SayHelloRunnable());}fixedExecutorService.shutdown();}}private class SayHelloRunnable implements Runnable {@Overridepublic void run() {try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch <span id="4_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="4_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=block&k0=block&kdi0=0&luki=7&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="4" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">block</span></a></span>e.printStackTrace();} finally {System.out.println("hello world!");}}}public static void main(String[] args) {TextExecutor testExecutor = new TextExecutor();testExecutor.testExecutorException();}
}

线程数量超过maximumPoolSize

示例代码里使用了自定义的ExecutorService,可以复现这种问题:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;public class TextExecutor {public ExecutorService fixedExecutorService = Executors.newFixedThreadPool(5);public ExecutorService cachedExecutorService = Executors.newCachedThreadPool();public ExecutorService singleExecutorService = Executors.newSingleThreadExecutor();public ExecutorService customerExecutorService = new ThreadPoolExecutor(3, 5, 0, TimeUnit.MILLISECONDS, new SynchronousQueue<Runnable>());public void testExecutorException() {for (int i = 0; i < 10; i ++) {// 增加isShutdown()判断if (!fixedExecutorService.isShutdown()) {fixedExecutorService.execute(new SayHelloRunnable());}fixedExecutorService.shutdown();}}public void testCustomerExecutorException() {for (int i = 0; i < 100; i ++) {customerExecutorService.execute(new SayHelloRunnable());}}private class SayHelloRunnable implements Runnable {@Overridepublic void run() {try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch <span id="3_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="3_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=block&k0=block&kdi0=0&luki=7&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="3" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">block</span></a></span>e.printStackTrace();} finally {System.out.println("hello world!");}}}public static void main(String[] args) {TextExecutor testExecutor = new TextExecutor();testExecutor.testCustomerExecutorException();;}
}

解决方案

1. 尽量调大maximumPoolSize,例如设置为Integer.MAX_VALUE
	public ExecutorService customerExecutorService = new ThreadPoolExecutor(3, Integer.MAX_VALUE, 0, TimeUnit.MILLISECONDS, new SynchronousQueue<Runnable>());
2. 使用其他排队策略,例如LinkedBlockingQueue
<<span id="0_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="0_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=span&k0=span&kdi0=0&luki=2&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="0" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">span</span></a></span> <span id="1_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="1_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=style&k0=style&kdi0=0&luki=6&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="1" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">style</span></a></span>="white-space:<span id="2_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="2_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=pre&k0=pre&kdi0=0&luki=5&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="2" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">pre</span></a></span>">	</span>public ExecutorService customerExecutorService = new ThreadPoolExecutor(3, 5, 0, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>());

ThreadPoolExecutor

一个ExecutorService,它使用可能的几个线程池之一执行每个提交的任务,通常使用Executors工厂方法配置,但是查看源码,发现工厂方法也是统一调用了ThreadPoolExecutor类,以为例,源码如下:
public class Executors {public static ExecutorService newFixedThreadPool(int nThreads) {return new ThreadPoolExecutor(nThreads, nThreads,0L, TimeUnit.MILLISECONDS,new LinkedBlockingQueue<Runnable>());}public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) {return new ThreadPoolExecutor(nThreads, nThreads,0L, TimeUnit.MILLISECONDS,new LinkedBlockingQueue<Runnable>(),threadFactory);}
}
虽然我一直认同 程序员应使用较为方便的Executors工厂方法Executors.newCachedThreadPool() (无界线程池,可以进行自动线程回收)、Executors.newFixedThreadPool(int)(固定大小线程池)和Executors.newSingleThreadExecutor()(单个后台线程),但是通过 源码我们可以发现最后他们均调用了ThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) 方法,因此我们在分析java.util.concurrent.RejectedExecutionException之前,需要深入学习一下ThreadPoolExecutor的使用。

核心池和最大池的大小

TreadPoolExecutor将根据corePoolSize和maximumPoolSize设置的边界自动调整池大小。当新任务在方法execute(java.lang.Runnable)中提交时,如果运行的线程少于corePoolSize,则创建新线程来处理请求,即使其他辅助线程是空闲的。如果运行的线程多于corePoolSize而少于maximumPoolSize,则仅当队列满时才创建新的线程。如果设置的corePoolSize和maximumPoolSize相同,则创建了固定大小的线程池。如果将maximumPoolSize设置为基本的无界值(如Integer.MAX_VALUE),则允许线程池适应任意数量的并发任务。

保持活动时间

如果池中当前有多于corePoolSize的线程,则这些多出的线程在空闲时间超过keepAliveTime时将会终止。

排队

所有BlockingQueue都可用于传输和保持提交的任务。可以使用此队列与池大小进行交互:
  • 如果运行的线程少于corePoolSize,则Executor始终首选添加新的线程,而不进行排队。
  • 如果运行的线程等于或多于corePoolSize,则Executor始终首选将请求加入队列,而不添加新的线程。
  • 如果无法将请求加入队列,则创建新的线程,除非创建此线程超出maximumPoolSize,在这种情况下,任务将被拒绝(抛出RejectedExecutionException)
排队有三种通用策略:
  1. 直接提交。工作队列的默认选项是synchronousQueue,它将任务直接提交给线程而不保持它们。在此,如果不存在可用于立即运行任务的线程,则试图把任务加入队列将失败,因此会构造一个新的线程。此策略可以避免在处理可能具有内部依赖性的请求集时出现锁。直接提交通常要求无界maximumPoolSizes以避免拒绝新提交的任务。当命令以超过队列所能处理的平均数连续到达时,此策略允许无界线程具有增加的可能性。
  2. 无界队列。使用无界队列(例如,不具有预定义容量的LinkedBlockingQueue)将导致在所有corePoolSize线程都忙时新任务在队列中等待。这样,创建的线程就不会超过corePoolSize(因此,maximumPoolSize的值也就无效了)。
  3. 有界队列。当使用有限的maximumPoolSizes时,有界队列(如ArrayBlockingQueue)有助于防止资源耗尽,但是可能较难调整和控制。队列大小和最大池大小可能需要相互折衷:使用大型队列和小型池可以最大限度的降低CPU使用率、操作系统资源和上下文切换开销,但是可能导致人工降低吞吐量。如果任务频繁阻塞,则系统可能为超过您许可的更多线程安排时间,使用小型队列通常要求较大的池大小,CPU使用率较高,但是可能遇到不可接受的调度开销,这样可会降低吞吐量。

终止

程序不再引用的池没有剩余线程会自动shutdown。如果希望确保回收取消引用的池(即使用户忘记调用shutdown()),则必须安排未使用的线程最终终止。

分析

通过对ThreadPoolExecutor类分析,引发java.util.concurrent.RejectedExecutionException主要有两种原因:
1. 线程池显示的调用了shutdown()之后,再向线程池提交任务的时候,如果你配置的拒绝策略是ThreadPoolExecutor.AbortPolicy的话,这个异常就被会抛出来。
2. 当你的排队策略为有界队列,并且配置的拒绝策略是ThreadPoolExecutor.AbortPolicy,当线程池的线程数量已经达到了maximumPoolSize的时候,你再向它提交任务,就会抛出ThreadPoolExecutor.AbortPolicy异常。

显示关闭掉线程池

这一点很好理解。比如说,你向一个 仓库去存放货物,一开始,仓库管理员把门给你打开了,你放了第一件商品到仓库里,但是当你放好出去后,有人把仓库门关了,那你下次再来存放物品时,你就会被拒绝。示例代码如下:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class TextExecutor {public ExecutorService fixedExecutorService = Executors.newFixedThreadPool(5);public ExecutorService cachedExecutorService = Executors.newCachedThreadPool();public ExecutorService singleExecutorService = Executors.newSingleThreadExecutor();public void testExecutorException() {for (int i = 0; i < 10; i ++) {fixedExecutorService.execute(new SayHelloRunnable());fixedExecutorService.shutdown();}}private class SayHelloRunnable implements Runnable {@Overridepublic void run() {try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch <span id="5_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="5_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=block&k0=block&kdi0=0&luki=7&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="5" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">block</span></a></span>e.printStackTrace();} finally {System.out.println("hello world!");}}}public static void main(String[] args) {TextExecutor testExecutor = new TextExecutor();testExecutor.testExecutorException();}
}

解决方案

1. 不要显示的调用shutdown方法,例如Android里,只有你在Destory方法里cancel掉AsyncTask,则线程池里没有活跃线程会自己回收自己。
2. 调用线程池时,判断是否已经shutdown,通过API方法isShutDown方法判断,示例代码:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class TextExecutor {public ExecutorService fixedExecutorService = Executors.newFixedThreadPool(5);public ExecutorService cachedExecutorService = Executors.newCachedThreadPool();public ExecutorService singleExecutorService = Executors.newSingleThreadExecutor();public void testExecutorException() {for (int i = 0; i < 10; i ++) {// 增加isShutdown()判断if (!fixedExecutorService.isShutdown()) {fixedExecutorService.execute(new SayHelloRunnable());}fixedExecutorService.shutdown();}}private class SayHelloRunnable implements Runnable {@Overridepublic void run() {try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch <span id="4_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="4_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=block&k0=block&kdi0=0&luki=7&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="4" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">block</span></a></span>e.printStackTrace();} finally {System.out.println("hello world!");}}}public static void main(String[] args) {TextExecutor testExecutor = new TextExecutor();testExecutor.testExecutorException();}
}

线程数量超过maximumPoolSize

示例代码里使用了自定义的ExecutorService,可以复现这种问题:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;public class TextExecutor {public ExecutorService fixedExecutorService = Executors.newFixedThreadPool(5);public ExecutorService cachedExecutorService = Executors.newCachedThreadPool();public ExecutorService singleExecutorService = Executors.newSingleThreadExecutor();public ExecutorService customerExecutorService = new ThreadPoolExecutor(3, 5, 0, TimeUnit.MILLISECONDS, new SynchronousQueue<Runnable>());public void testExecutorException() {for (int i = 0; i < 10; i ++) {// 增加isShutdown()判断if (!fixedExecutorService.isShutdown()) {fixedExecutorService.execute(new SayHelloRunnable());}fixedExecutorService.shutdown();}}public void testCustomerExecutorException() {for (int i = 0; i < 100; i ++) {customerExecutorService.execute(new SayHelloRunnable());}}private class SayHelloRunnable implements Runnable {@Overridepublic void run() {try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch <span id="3_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="3_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=block&k0=block&kdi0=0&luki=7&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="3" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">block</span></a></span>e.printStackTrace();} finally {System.out.println("hello world!");}}}public static void main(String[] args) {TextExecutor testExecutor = new TextExecutor();testExecutor.testCustomerExecutorException();;}
}

解决方案

1. 尽量调大maximumPoolSize,例如设置为Integer.MAX_VALUE
	public ExecutorService customerExecutorService = new ThreadPoolExecutor(3, Integer.MAX_VALUE, 0, TimeUnit.MILLISECONDS, new SynchronousQueue<Runnable>());
2. 使用其他排队策略,例如LinkedBlockingQueue
<<span id="0_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="0_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=span&k0=span&kdi0=0&luki=2&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="0" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">span</span></a></span> <span id="1_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="1_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=style&k0=style&kdi0=0&luki=6&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="1" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">style</span></a></span>="white-space:<span id="2_nwp" style="padding: 0px; width: auto; height: auto; float: none;"><a target=_blank id="2_nwl" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=18&is_app=0&jk=9610e3e4b16d0f40&k=pre&k0=pre&kdi0=0&luki=5&n=10&p=baidu&q=65035100_cpr&rb=0&rs=1&seller_id=1&sid=400f6db1e4e31096&ssp2=1&stid=0&t=tpclicked3_hc&td=1836545&tu=u1836545&u=http%3A%2F%2Fwww%2Ebubuko%2Ecom%2Finfodetail%2D339153%2Ehtml&urlid=0" target="_blank" mpid="2" style="padding: 0px; color: rgb(51, 51, 51); text-decoration: none;"><span style="padding: 0px; color: rgb(0, 0, 255); width: auto; height: auto;">pre</span></a></span>">	</span>public ExecutorService customerExecutorService = new ThreadPoolExecutor(3, 5, 0, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>());

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