共用threadpool导致死锁问题

threadpooldeadlock.java

import java.util.concurrent.*;
import java.util.stream.IntStream;

/**
 * @author yuzd
 * @date 2022/12/1 16:24
 */
public class PoolTest {

    // 模拟nio线程池
    static ThreadPoolExecutor nioExecutor = new ThreadPoolExecutor(20, 20, 60, TimeUnit.SECONDS, new LinkedBlockingQueue<>(100),
            new CustomerNamedThreadFactory("nio", false),
            new ThreadPoolExecutor.AbortPolicy());

    // 业务线程池
    static ThreadPoolExecutor buExecutor = new ThreadPoolExecutor(20, 20, 60, TimeUnit.SECONDS, new LinkedBlockingQueue<>(100),
            new CustomerNamedThreadFactory("bu", true),
            new ThreadPoolExecutor.AbortPolicy());

    public static void main(String[] args) {

        // 模拟是http请求并发20个
        IntStream.rangeClosed(1, 20).parallel().forEach((index) -> {
            // 交给nio线程池处理            
            nioExecutor.execute(() -> {
                try {
                    httpHandler(index);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            });
        });
    }


   
    static void httpHandler(int index) throws ExecutionException, InterruptedException {
        System.out.println(Thread.currentThread().getName() + " request index :" + index + " staring");
        // 交给业务线程池处理     
       
        Future<String> parentFuture = buExecutor.submit(() -> process1(index));
        String p1Rt = parentFuture.get();  // nio线程在wait
        System.out.println(Thread.currentThread().getName() + " request index :" + p1Rt + " ending");
    }

    // future1
    static String process1(int index) throws ExecutionException, InterruptedException {
        System.out.println( Thread.currentThread().getName() + " process1 index :" + index + " staring");
        Future<String> childFuture = buExecutor.submit(() -> process2(index));
        String p2Rt = childFuture.get();  // 这里是bu线程在wait   这里会发生死锁
        
        System.out.println(Thread.currentThread().getName() + " process1 index :" + index + " ending");
        return p2Rt;
    }

    // future2
    static String process2(int index) throws InterruptedException, ExecutionException {
        System.out.println(Thread.currentThread().getName() + " process2 index :" + index + " staring");
        // 加上就会死锁 
        // 只要不一下子产生足够数量的task（把core全部占掉）就不会死锁 加了这里就会把core全部占据 导致task进入到queue，core线程在wait future.get 无法被释放， 而queue的任务在等待它释放产生新的线程
        Future<String> submit = buExecutor.submit(() -> {
            try {
                Thread.sleep(1000);
                return String.valueOf(index);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        });
        submit.get(); 
        System.out.println(Thread.currentThread().getName() + " process2 index :" + index + " ending");
        return String.valueOf(index);
    }
}