面试题：Java线程池自定义异常处理及恢复机制实现

自定义异常处理机制：

实现Thread.UncaughtExceptionHandler接口：

public class CustomUncaughtExceptionHandler implements Thread.UncaughtExceptionHandler {
    @Override
    public void uncaughtException(Thread t, Throwable e) {
        // 记录异常日志
        System.err.println("Thread " + t.getName() + " threw an exception: " + e.getMessage());
        e.printStackTrace();
        // 这里可以根据异常类型判断是否是特定异常
        if (e instanceof YourSpecificException) {
            // 处理特定异常的逻辑
        }
    }
}

将自定义的UncaughtExceptionHandler应用到线程池中的线程：

ThreadFactory customThreadFactory = new ThreadFactory() {
    @Override
    public Thread newThread(Runnable r) {
        Thread thread = new Thread(r);
        thread.setUncaughtExceptionHandler(new CustomUncaughtExceptionHandler());
        return thread;
    }
};

然后在创建线程池时使用这个自定义的ThreadFactory：

ExecutorService executorService = new ThreadPoolExecutor(
        corePoolSize,
        maximumPoolSize,
        keepAliveTime,
        TimeUnit.SECONDS,
        new LinkedBlockingQueue<>(),
        customThreadFactory);

动态调整线程池参数的恢复逻辑：

获取ThreadPoolExecutor实例：因为ExecutorService接口没有直接提供修改线程池参数的方法，所以需要将线程池转换为ThreadPoolExecutor。

if (executorService instanceof ThreadPoolExecutor) {
    ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executorService;
}

动态调整参数：在CustomUncaughtExceptionHandler的uncaughtException方法中，当捕获到特定异常时，进行参数调整。例如，增加核心线程数：

@Override
public void uncaughtException(Thread t, Throwable e) {
    if (e instanceof YourSpecificException) {
        if (executorService instanceof ThreadPoolExecutor) {
            ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executorService;
            int newCorePoolSize = threadPoolExecutor.getCorePoolSize() + 1;
            threadPoolExecutor.setCorePoolSize(newCorePoolSize);
        }
    }
}

注意：动态调整线程池参数需要谨慎，要根据具体的业务场景和系统资源情况进行合理的调整，避免过度调整导致系统性能问题。同时，异常处理逻辑中可以结合监控和报警机制，以便及时发现和处理异常情况。

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面试题：Java线程池自定义异常处理及恢复机制实现

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