ThreadPoolExecutor是如何处理任务的异常情况

本文因生产环境线程池某些场景下的任务异常后，日志文件中没有被记录进来产生的困惑引发的思考。
当然如果所有异步的业务方法run里面都加上一层try…catch…就可以主动捕获所有的异常，也能够记录到日志文件中，然而总有一些人总有一些时候不小心漏掉了，今天分享下run方法如果不加try…catch…的后果

测试调用execute

//测试代码
public static void testExecute() {

    ThreadPoolExecutor pool = new ThreadPoolExecutor(1, 1, 0, TimeUnit.DAYS,
        new LinkedBlockingQueue<>(), new MyThreadFactory(), new ThreadPoolExecutor.AbortPolicy());

    for (int i = 0; i < 5; i++) {
        int finalI = i;
        pool.execute(() -> {

            if (finalI == 3) {
                throw new RuntimeException("abcdefg");
            }
            logger.info("lzc" + finalI);

        });

    }
}

//测试结果  控制台输出
2020-06-04 00:00:50.118 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         91 lzc0
2020-06-04 00:00:50.122 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         91 lzc1
2020-06-04 00:00:50.122 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         91 lzc2
2020-06-04 00:00:51.837 INFO  pool-1-thread-2 com.alioo.pool.ExceptionPoolDemo         91 lzc4
Exception in thread "pool-1-thread-1" 
java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$testExecute$2(ExceptionPoolDemo.java:89)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

//测试结果  日志文件输出
2020-06-04 00:00:50.118 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         91 lzc0
2020-06-04 00:00:50.122 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         91 lzc1
2020-06-04 00:00:50.122 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         91 lzc2
2020-06-04 00:00:51.837 INFO  pool-1-thread-2 com.alioo.pool.ExceptionPoolDemo         91 lzc4

测试结论

1.控制台会有异常堆栈信息 , 然而日志文件中却没有记录这条异常，这个很致命，异步处理的线程出现了异常，日志没有记录事件，事后很难排查
2.corePoolSize设置的是1 , blockinqueue使用的是无界队列，正常情况下,始终只会有一个线程来所有任务，即pool-1-thread-1，然而从上面的日志可以发现有新线程pool-1-thread-2参加工作了

测试调用submit

//测试代码
public static void testSubmit() {

    ThreadPoolExecutor pool = new ThreadPoolExecutor(1, 1, 0, TimeUnit.DAYS,
        new LinkedBlockingQueue<>(), new MyThreadFactory(), new ThreadPoolExecutor.AbortPolicy());

    for (int i = 0; i < 5; i++) {
        int finalI = i;
        pool.submit(() -> {

            if (finalI == 3) {
                throw new RuntimeException("abcdefg");
            }
            logger.info("lzc" + finalI);

        });



    }
}

//测试结果  控制台输出

2020-06-04 00:15:25.069 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc0
2020-06-04 00:15:25.072 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc1
2020-06-04 00:15:25.072 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc2
2020-06-04 00:15:25.073 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc4

//测试结果  日志文件输出
2020-06-04 00:15:25.069 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc0
2020-06-04 00:15:25.072 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc1
2020-06-04 00:15:25.072 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc2
2020-06-04 00:15:25.073 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         112 lzc4

测试结论

1.这个更要命，控制台与日志文件都没有记录这条异常，后果同上
2.submit时没有使用新工作线程，使用始终使用的是pool-1-thread-1

测试调用submit+future.get()

//测试代码
public static void testSubmitFuture() {

    ThreadPoolExecutor pool = new ThreadPoolExecutor(1, 1, 0, TimeUnit.DAYS,
        new LinkedBlockingQueue<>(), new MyThreadFactory(), new ThreadPoolExecutor.AbortPolicy());

    List<Future> list = new ArrayList<>();
    for (int i = 0; i < 5; i++) {
        int finalI = i;
        Future f = pool.submit(() -> {
            if (finalI == 3) {
                throw new RuntimeException("abcdefg");
            }
            logger.info("lzc" + finalI);

        });
        list.add(f);
    }

    for (Future f : list) {
        try {
            f.get();
        } catch (Exception e) {
            logger.error("出现了异常", e);
        }
    }

}

//测试结果  控制台输出

2020-06-04 00:18:55.784 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc0
2020-06-04 00:18:55.787 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc1
2020-06-04 00:18:55.787 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc2
2020-06-04 00:18:55.787 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc4
2020-06-04 00:18:55.790 ERROR main com.alioo.pool.ExceptionPoolDemo         144 出现了异常
java.util.concurrent.ExecutionException: java.lang.RuntimeException: abcdefg
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at com.alioo.pool.ExceptionPoolDemo.testSubmitFuture(ExceptionPoolDemo.java:142)
	at com.alioo.pool.ExceptionPoolDemo.main(ExceptionPoolDemo.java:153)
Caused by: java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$testSubmitFuture$4(ExceptionPoolDemo.java:132)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
	at java.util.concurrent.FutureTask.run(FutureTask.java)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

//测试结果  日志文件输出
2020-06-04 00:18:55.784 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc0
2020-06-04 00:18:55.787 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc1
2020-06-04 00:18:55.787 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc2
2020-06-04 00:18:55.787 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         134 lzc4
2020-06-04 00:18:55.790 ERROR main com.alioo.pool.ExceptionPoolDemo         144 出现了异常
java.util.concurrent.ExecutionException: java.lang.RuntimeException: abcdefg
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at com.alioo.pool.ExceptionPoolDemo.testSubmitFuture(ExceptionPoolDemo.java:142)
	at com.alioo.pool.ExceptionPoolDemo.main(ExceptionPoolDemo.java:153)
Caused by: java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$testSubmitFuture$4(ExceptionPoolDemo.java:132)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
	at java.util.concurrent.FutureTask.run(FutureTask.java)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

测试结论

1.future.get()表示接收返回值，当调用future.get()后，控制台与日志文件均记录下来了，完美！
2.submit时没有使用新工作线程，使用始终使用的是pool-1-thread-1

原因分析

原因分析 execute

线程池的工作线程类Worker实现了Runnable接口，接下来主要分析Worker的构造方法与run方法

Worker(Runnable firstTask) {
    setState(-1); // inhibit interrupts until runWorker
    this.firstTask = firstTask;
    this.thread = getThreadFactory().newThread(this);
}

public void run() {
    runWorker(this);
}
        
        

解码：

1. Worker的构造方法中调用getThreadFactory().newThread(this);通过工厂方法来创建工作线程
2. 上面的测试代码创建pool时使用的是MyThreadFactory,代码在文章最后，上面测试的案例使用的MyThreadFactory跟Executors.defaultThreadFactory()一模一样
3. 创建线程前被要求先创建一个group,阅读代码会发现group其实是Thread.currentThread().getThreadGroup()，ThreadGroup实现了Thread.UncaughtExceptionHandler接口

Thread t = new Thread(group, r,
        namePrefix + threadNumber.getAndIncrement(),
       0);

4. 分析下ThreadGroup.uncaughtException方法，当线程出现未捕获的异常时就会进入到这里，看代码有点类似于双亲委派机制，优先交给parent来处理异常。
   实际断点发现会进入2次这个方法，第1次由于parent不为空(parent:java.lang.ThreadGroup[name=system,maxpri=10])，第2次为空
   第2次进入后，ueh为null,所以执行了else if代码块，结果跟上面测试execute会发现是可以对上的

public void uncaughtException(Thread t, Throwable e) {
    if (parent != null) {
        parent.uncaughtException(t, e);
    } else {
        Thread.UncaughtExceptionHandler ueh =
            Thread.getDefaultUncaughtExceptionHandler();
        if (ueh != null) {
            ueh.uncaughtException(t, e);
        } else if (!(e instanceof ThreadDeath)) {
            System.err.print("Exception in thread \""
                             + t.getName() + "\" ");
            e.printStackTrace(System.err);
        }
    }
}

5. 前面几步分析是有个前提的，就是当Worker线程出现了未捕获的异常才能走上面的uncaughtException方法，虽然我们之前交待了业务方法出现了异常未捕获，但是还要进一步看看Worker.run()方法是否会帮我们try…catch…
   （这里也很关键，也是这里的代码差异造成了上面3种不同的结果）
   Worker.run()方法直接调用了runWorker()方法

    final void runWorker(Worker w) {
        Thread wt = Thread.currentThread();
        Runnable task = w.firstTask;
        w.firstTask = null;
        w.unlock(); // allow interrupts
        boolean completedAbruptly = true;
        try {
            while (task != null || (task = getTask()) != null) {
                w.lock();
                // If pool is stopping, ensure thread is interrupted;
                // if not, ensure thread is not interrupted.  This
                // requires a recheck in second case to deal with
                // shutdownNow race while clearing interrupt
                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();                  //这里是我们自己写的业务方法，业务逻辑都在这里
                    } catch (RuntimeException x) {
                        thrown = x; throw x;         //第1层try...块，业务逻辑会抛出RuntimeException，所以会进入到这里，这里虽然捕获了，然而又throw了
                    } catch (Error x) {
                        thrown = x; throw x;
                    } catch (Throwable x) {
                        thrown = x; throw new Error(x);
                    } finally {
                        afterExecute(task, thrown);
                    }
                } finally {                       //第2层try...块，这里的try...块没有catch,是不是很惊喜，收到第1个层throw出现的RuntimeException只需要做finally逻辑，然后RuntimeException继续往外抛
                    task = null;
                    w.completedTasks++;
                    w.unlock();
                }
            }
            completedAbruptly = false;
        } finally {                             //第3层try...块，这里的try...块依旧没有catch,收到第2层throw出现的RuntimeException依旧只需要做finally逻辑，继续往外抛RuntimeException
                                                //然而已经到最外层了，还没有被catch住的话就会交给Thread.currentThread().getThreadGroup().uncaughtException进行处理了。
            processWorkerExit(w, completedAbruptly);
        }
    }

原因分析 submit

前面已经铺垫了Worker.run()方法代码差异造成了submit后异常处理的不同，接下来具体分析下吧

1. submit方法调用时对原始的业务方法对象task进行了包装，生成了新的Rannable对象FutureTask

public Future<?> submit(Runnable task) {
    if (task == null) throw new NullPointerException();
    RunnableFuture<Void> ftask = newTaskFor(task, null);
    execute(ftask);
    return ftask;
}

protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
    return new FutureTask<T>(runnable, value);
}
    

2. 下面是Rannable对象FutureTask对象的run方法，会在这个里面调用原始的业务方法```c.call()``

public void run() {
    if (state != NEW ||
        !UNSAFE.compareAndSwapObject(this, runnerOffset,
                                     null, Thread.currentThread()))
        return;
    try {
        Callable<V> c = callable;
        if (c != null && state == NEW) {
            V result;
            boolean ran;
            try {
                result = c.call();             //原始的业务方法call()会在这里进行调用
                ran = true;
            } catch (Throwable ex) {
                result = null;                //第1层try...块，这里的try...块遇到RuntimeException直接吃掉了，并没有继续往外抛
                ran = false;
                setException(ex);             //进入这个方法会将ex赋值到outcome对象中（注意正常情况下outcome存放的是方法返回值result）
            }
            if (ran)
                set(result);
        }
    } finally {
        // runner must be non-null until state is settled to
        // prevent concurrent calls to run()
        runner = null;
        // state must be re-read after nulling runner to prevent
        // leaked interrupts
        int s = state;
        if (s >= INTERRUPTING)                    //第2层try...块，当出现异常时，这里的if不会进去执行
            handlePossibleCancellationInterrupt(s);
    }                                            
}


protected void setException(Throwable t) {
    if (UNSAFE.compareAndSwapInt(this, stateOffset, NEW, COMPLETING)) {
        outcome = t;
        UNSAFE.putOrderedInt(this, stateOffset, EXCEPTIONAL); // final state
        finishCompletion();
    }
}
    

3. 当整个run方法执行完成后，异常存放到了outcome属性中,并没有任何地方打印输出，所以跟前面测试submit情况也是符合的

原因分析 submit+future.get()

前面的测试结论中可以看到只调用submit时异常信息是没有任何输出的，而当调用了future.get()异常就出来了，这是为什么呢，下面对着源码来揭晓答案

1. 由前面的代码我们知道Future实现是FutureTask，查看下FutureTask.get()。异常发生时state= (EXCEPTIONAL = 3),这个方法中的if不会进去，直接会调用report(s)
   report(s)中的2个if也不满足条件，也不会执行，最终就会执行throw new ExecutionException((Throwable)x);，好了，这就是只调用submit不会输出异常，而当进一步调用future.get()就会触发往外抛异常了

private volatile int state;
private static final int NEW          = 0;
private static final int COMPLETING   = 1;
private static final int NORMAL       = 2;
private static final int EXCEPTIONAL  = 3;
private static final int CANCELLED    = 4;
private static final int INTERRUPTING = 5;
private static final int INTERRUPTED  = 6;

public V get() throws InterruptedException, ExecutionException {
    int s = state;
    if (s <= COMPLETING)
        s = awaitDone(false, 0L);
    return report(s);
}

private V report(int s) throws ExecutionException {
    Object x = outcome;
    if (s == NORMAL)
        return (V)x;
    if (s >= CANCELLED)
        throw new CancellationException();
    throw new ExecutionException((Throwable)x);
}

2. 由于future.get()方法强制要求调用方捕获异常，所以我们在调用的地方使用了try…catch…,前面测试时看到的异常日志都来源自这里的logger.error("出现了异常", e);

for (Future f : list) {
    try {
        f.get();
    } catch (Exception e) {
        logger.error("出现了异常", e);
    }
}
    

3. 细心的你或许会发现这个地方的异常堆栈比较奇怪，先打印了ExecutionException，后来又打印了RuntimeException，这里因为report方法中对原始异常RuntimeException又包了一层ExecutionException
   本质上还是只有1个异常的，这样做是有好处的既告诉了你你捕获的异常是从哪里发起的ExecutionException，又告诉了你原始异常发生的地方

2020-06-04 00:18:55.790 ERROR main com.alioo.pool.ExceptionPoolDemo         144 出现了异常
java.util.concurrent.ExecutionException: java.lang.RuntimeException: abcdefg
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at com.alioo.pool.ExceptionPoolDemo.testSubmitFuture(ExceptionPoolDemo.java:142)
	at com.alioo.pool.ExceptionPoolDemo.main(ExceptionPoolDemo.java:153)
Caused by: java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$testSubmitFuture$4(ExceptionPoolDemo.java:132)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
	at java.util.concurrent.FutureTask.run(FutureTask.java)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

附文中使用了自定义的ThreadFactory，实现与Executors.defaultThreadFactory()一模一样

import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;

public class MyThreadFactory implements ThreadFactory {
    private static final AtomicInteger poolNumber = new AtomicInteger(1);
    private final ThreadGroup group;
    private final AtomicInteger threadNumber = new AtomicInteger(1);
    private final String namePrefix;

    public  MyThreadFactory() {
        SecurityManager s = System.getSecurityManager();
        group = (s != null) ? s.getThreadGroup() :
            Thread.currentThread().getThreadGroup();
        namePrefix = "pool-" +
            poolNumber.getAndIncrement() +
            "-thread-";
    }

    public Thread newThread(Runnable r) {
        Thread t = new Thread(group, r,
            namePrefix + threadNumber.getAndIncrement(),
            0);
        if (t.isDaemon())
            t.setDaemon(false);
        if (t.getPriority() != Thread.NORM_PRIORITY)
            t.setPriority(Thread.NORM_PRIORITY);
        return t;
    }
}

兜底解决方案

上面分别分析了execute,submit在业务方法未捕获异常时的表现，当异常发生时不能记录到日志文件中后续定位问题是非常麻烦的，那么作为线程框架可以有哪些解决手段呢？

业务方法自行try…catch…,首选方案吧，强烈建议这样子做

runWorker()方法中会调用afterExecute(task, thrown),可以在重写这个方法对异常进行日志记录

这里需要说明的是重写了afterExecute(task, thrown)只是增加了对异常的日志打印，但是异常还是会继续往外抛出，所以控制台会打印2次异常日志，但是日志文件只会打印1次(未重写afterExecute时，控制台打印1次，日志文件0次)

//测试代码

public static void afterExecute() {
    ThreadPoolExecutor executorService = new ThreadPoolExecutor(1, 1, 0, TimeUnit.DAYS,
        new LinkedBlockingQueue<>()) {
        @Override
        protected void afterExecute(Runnable r, Throwable t) {
            super.afterExecute(r, t);
            if (t != null) {
                logger.error("出现了异常", t);
            }
        }
    };

    for (int i = 0; i < 5; i++) {
        int finalI = i;
        executorService.execute(() -> {

            if (finalI == 3) {
                throw new RuntimeException("aabb");
            }
            logger.info("lzc" + finalI);

        });

    }

}

//测试结果  控制台输出
2020-06-04 12:51:42.070 INFO  pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         35 lzc0
2020-06-04 12:51:42.073 INFO  pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         35 lzc1
2020-06-04 12:51:42.073 INFO  pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         35 lzc2
2020-06-04 12:51:55.549 ERROR pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         23 出现了异常
java.lang.RuntimeException: aabb
	at com.alioo.pool.ExceptionPoolDemo.lambda$afterExecute$0(ExceptionPoolDemo.java:33)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
2020-06-04 12:51:55.552 INFO  pool-2-thread-2 com.alioo.pool.ExceptionPoolDemo         35 lzc4
Exception in thread "pool-2-thread-1" java.lang.RuntimeException: aabb
	at com.alioo.pool.ExceptionPoolDemo.lambda$afterExecute$0(ExceptionPoolDemo.java:33)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)


//测试结果  日志文件输出
2020-06-04 12:51:42.070 INFO  pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         35 lzc0
2020-06-04 12:51:42.073 INFO  pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         35 lzc1
2020-06-04 12:51:42.073 INFO  pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         35 lzc2
2020-06-04 12:51:55.549 ERROR pool-2-thread-1 com.alioo.pool.ExceptionPoolDemo         23 出现了异常
java.lang.RuntimeException: aabb
	at com.alioo.pool.ExceptionPoolDemo.lambda$afterExecute$0(ExceptionPoolDemo.java:33)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
2020-06-04 12:51:55.552 INFO  pool-2-thread-2 com.alioo.pool.ExceptionPoolDemo         35 lzc4

自定义ThreadGroup

这里使用了自定义的MyThreadFactory，在MyThreadFactory中创建线程时使用自定义的MyThreadGroup，并且重写了uncaughtException方法，当遇到异常时记录到日志文件里

//测试代码
public static void myThreadGroup() {

    ThreadPoolExecutor pool = new ThreadPoolExecutor(1, 1, 0, TimeUnit.DAYS,
        new LinkedBlockingQueue<>(), new MyThreadFactory(), new ThreadPoolExecutor.AbortPolicy());

    for (int i = 0; i < 5; i++) {
        int finalI = i;
        pool.execute(() -> {

            if (finalI == 3) {
                throw new RuntimeException("abcdefg");
            }
            logger.info("lzc" + finalI);

        });

    }
}



public class MyThreadFactory implements ThreadFactory {

    private static final AtomicInteger poolNumber = new AtomicInteger(1);
    private final ThreadGroup group;
    private final AtomicInteger threadNumber = new AtomicInteger(1);
    private final String namePrefix;

    public MyThreadFactory() {
        SecurityManager s = System.getSecurityManager();
        group = new MyThreadGroup("mythreadgroup");
        namePrefix = "pool-" +
            poolNumber.getAndIncrement() +
            "-thread-";
    }

    @Override
    public Thread newThread(Runnable r) {
        Thread t = new Thread(group, r,
            namePrefix + threadNumber.getAndIncrement(),
            0);
        if (t.isDaemon()) { t.setDaemon(false); }
        if (t.getPriority() != Thread.NORM_PRIORITY) { t.setPriority(Thread.NORM_PRIORITY); }
        return t;
    }
}

class MyThreadGroup extends ThreadGroup {
    private static Logger logger = LoggerFactory.getLogger(MyThreadGroup.class);

    public MyThreadGroup(String name) {
        super(name);
    }

    @Override
    public void uncaughtException(Thread t, Throwable e) {
        //if (parent != null) {
        //    parent.uncaughtException(t, e);
        //} else {
        Thread.UncaughtExceptionHandler ueh =
            Thread.getDefaultUncaughtExceptionHandler();
        if (ueh != null) {
            ueh.uncaughtException(t, e);
        } else if (!(e instanceof ThreadDeath)) {
            logger.error("兄弟，你的业务方法出现异常咋不处理呢，Exception in thread \""
                + t.getName() + "\" ",e);

        }
        //}
    }
}

//测试结果  控制台输出

2020-06-04 13:59:37.517 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         55 lzc0
2020-06-04 13:59:37.522 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         55 lzc1
2020-06-04 13:59:37.522 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         55 lzc2
2020-06-04 13:59:37.618 INFO  pool-1-thread-2 com.alioo.pool.ExceptionPoolDemo         55 lzc4
2020-06-04 13:59:37.622 ERROR pool-1-thread-1 com.alioo.pool.MyThreadGroup             52 兄弟，你的业务方法出现异常咋不处理呢，Exception in thread "pool-1-thread-1" 
java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$uncaughtExceptionHandler$1(ExceptionPoolDemo.java:53)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)


//测试结果  日志文件输出
2020-06-04 13:59:37.517 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         55 lzc0
2020-06-04 13:59:37.522 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         55 lzc1
2020-06-04 13:59:37.522 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         55 lzc2
2020-06-04 13:59:37.618 INFO  pool-1-thread-2 com.alioo.pool.ExceptionPoolDemo         55 lzc4
2020-06-04 13:59:37.622 ERROR pool-1-thread-1 com.alioo.pool.MyThreadGroup             52 兄弟，你的业务方法出现异常咋不处理呢，Exception in thread "pool-1-thread-1"
java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$uncaughtExceptionHandler$1(ExceptionPoolDemo.java:53)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
	
	

设置UncaughtExceptionHandler

跟上面的方法类似，都是重写ThreadFactory，上面是在创建线程时指定ThreadGroup，现在是线程按照默认方式创建完了，重置下ThreadGroup，仅此而已。

//测试代码
public static void uncaughtExceptionHandler() {

    ThreadPoolExecutor pool = new ThreadPoolExecutor(1, 1, 0, TimeUnit.DAYS,
        new LinkedBlockingQueue<>(), new MyThreadFactory2(), new ThreadPoolExecutor.AbortPolicy());

    for (int i = 0; i < 5; i++) {
        int finalI = i;
        pool.execute(() -> {

            if (finalI == 3) {
                throw new RuntimeException("abcdefg");
            }
            logger.info("lzc" + finalI);

        });

    }
}

public class MyThreadFactory2 implements ThreadFactory {
    private static final AtomicInteger poolNumber = new AtomicInteger(1);
    private final ThreadGroup group;
    private final AtomicInteger threadNumber = new AtomicInteger(1);
    private final String namePrefix;

    MyThreadFactory2() {
        SecurityManager s = System.getSecurityManager();
        group = (s != null) ? s.getThreadGroup() :
            Thread.currentThread().getThreadGroup();
        namePrefix = "pool-" +
            poolNumber.getAndIncrement() +
            "-thread-";
    }

    public Thread newThread(Runnable r) {
        Thread t = new Thread(group, r,
            namePrefix + threadNumber.getAndIncrement(),
            0);
        if (t.isDaemon())
            t.setDaemon(false);
        if (t.getPriority() != Thread.NORM_PRIORITY)
            t.setPriority(Thread.NORM_PRIORITY);

        t.setUncaughtExceptionHandler(new MyThreadGroup2("mythreadgroup"));
        return t;
    }
}

class MyThreadGroup2 extends ThreadGroup {
    private static Logger logger = LoggerFactory.getLogger(MyThreadGroup.class);

    public MyThreadGroup2(String name) {
        super(name);
    }

    @Override
    public void uncaughtException(Thread t, Throwable e) {
        //if (parent != null) {
        //    parent.uncaughtException(t, e);
        //} else {
        Thread.UncaughtExceptionHandler ueh =
            Thread.getDefaultUncaughtExceptionHandler();
        if (ueh != null) {
            ueh.uncaughtException(t, e);
        } else if (!(e instanceof ThreadDeath)) {
            logger.error("兄弟，你的业务方法出现异常咋不处理呢，Exception in thread \""
                + t.getName() + "\" ",e);

        }
        //}
    }
}

//测试结果  控制台输出
2020-06-04 14:17:57.439 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         74 lzc0
2020-06-04 14:17:57.443 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         74 lzc1
2020-06-04 14:17:57.443 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         74 lzc2
2020-06-04 14:17:58.047 INFO  pool-1-thread-2 com.alioo.pool.ExceptionPoolDemo         74 lzc4
2020-06-04 14:17:58.049 ERROR pool-1-thread-1 com.alioo.pool.MyThreadGroup             55 兄弟，你的业务方法出现异常咋不处理呢，Exception in thread "pool-1-thread-1" 
java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$uncaughtExceptionHandler$2(ExceptionPoolDemo.java:72)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

	
//测试结果  日志文件输出
2020-06-04 14:17:57.439 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         74 lzc0
2020-06-04 14:17:57.443 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         74 lzc1
2020-06-04 14:17:57.443 INFO  pool-1-thread-1 com.alioo.pool.ExceptionPoolDemo         74 lzc2
2020-06-04 14:17:58.047 INFO  pool-1-thread-2 com.alioo.pool.ExceptionPoolDemo         74 lzc4
2020-06-04 14:17:58.049 ERROR pool-1-thread-1 com.alioo.pool.MyThreadGroup             55 兄弟，你的业务方法出现异常咋不处理呢，Exception in thread "pool-1-thread-1"
java.lang.RuntimeException: abcdefg
	at com.alioo.pool.ExceptionPoolDemo.lambda$uncaughtExceptionHandler$2(ExceptionPoolDemo.java:72)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
	

参考文章
https://www.cnblogs.com/Laymen/p/11465881.html