“
一个线程池中的线程异常了，那么线程池会怎么处理这个线程?
需要说明，本文的线程池都是
java.util.concurrent.ExecutorService
线程池，本文将围绕验证，阅读源码俩方面来解析这个问题。
代码验证
验证execute提交线程池中
测试代码：
public class ThreadPoolExecutorDeadTest {
public static void main(String[] args) throws InterruptedException {
ExecutorService executorService = buildThreadPoolExecutor();
executorService.execute(() -> exeTask("execute"));
executorService.execute(() -> exeTask("execute"));
executorService.execute(() -> exeTask("execute-exception"));
executorService.execute(() -> exeTask("execute"));
executorService.execute(() -> exeTask("execute"));
Thread.sleep(5000);
System.out.println("再次执行任务=======================");
executorService.execute(() -> exeTask("execute"));
executorService.execute(() -> exeTask("execute"));
executorService.execute(() -> exeTask("execute"));
executorService.execute(() -> exeTask("execute"));
executorService.execute(() -> exeTask("execute"));
}
public static ExecutorService buildThreadPoolExecutor() {
return new ThreadPoolExecutor(5, 10, 30, TimeUnit.SECONDS,
new LinkedBlockingQueue<>(1000), new ThreadFactoryBuilder().setNameFormat("test-%s").build()
, new ThreadPoolExecutor.CallerRunsPolicy());
}
private static void exeTask(String name) {
String printStr = "[thread-name:" + Thread.currentThread().getName() + ",执行方式:" + name + "]";
if ("execute-exception".equals(name)) {
throw new RuntimeException(printStr + ", 我抛异常了");
} else {
System.out.println(printStr);
}
}
}
执行结果如下：
结论：
“
execute 提交到线程池的方式，如果执行中抛出异常，并且没有在执行逻辑中catch，那么会抛出异常，并且移除抛出异常的线程，创建新的线程放入到线程池中。
验证submit提交线程池中
测试代码：
public class ThreadPoolExecutorDeadTest {
public static void main(String[] args) throws InterruptedException {
ExecutorService executorService = buildThreadPoolExecutor();
executorService.submit(() -> exeTask("execute"));
executorService.submit(() -> exeTask("execute"));
executorService.submit(() -> exeTask("execute-exception"));
executorService.submit(() -> exeTask("execute"));
executorService.submit(() -> exeTask("execute"));
Thread.sleep(5000);
System.out.println("再次执行任务=======================");
executorService.submit(() -> exeTask("execute"));
executorService.submit(() -> exeTask("execute"));
executorService.submit(() -> exeTask("execute"));
executorService.submit(() -> exeTask("execute"));
executorService.submit(() -> exeTask("execute"));
}
public static ExecutorService buildThreadPoolExecutor() {
return new ThreadPoolExecutor(5, 10, 30, TimeUnit.SECONDS,
new LinkedBlockingQueue<>(1000), new ThreadFactoryBuilder().setNameFormat("test-%s").build()
, new ThreadPoolExecutor.CallerRunsPolicy());
}
private static void exeTask(String name) {
String printStr = "[thread-name:" + Thread.currentThread().getName() + ",执行方式:" + name + "]";
if ("execute-exception".equals(name)) {
throw new RuntimeException(printStr + ", 我抛异常了");
} else {
System.out.println(printStr);
}
}
}
执行结果如下：
结论：
“
submit 提交到线程池的方式，如果执行中抛出异常，并且没有catch，不会抛出异常，不会创建新的线程。
源码解析
1
java.util.concurrent.AbstractExecutorService#submit(java.lang.Runnable)
2 查看execute方法的执行逻辑
java.util.concurrent.ThreadPoolExecutor#runWorker
3
java.util.concurrent.ThreadPoolExecutor#processWorkerExit
“
可以发现，如果抛出异常，会移除抛出异常的线程，创建新的线程。
4 为什么submit方法，没有创建新的线程，而是继续复用原线程？
还记得，我们在3.1的时候，发现submit也是调用了execute方法，但是在调用之前,包装了一层 RunnableFuture，那一定是在RunnableFuture的实现 FutureTask中有特殊处理了，我们查看源码可以发现。
但是，我们通过
java.util.concurrent.FutureTask#get()
，就可以获取对应的异常信息。
