rejected from java.util.concurrent.ThreadPoolExecutor@4ee285c6[Running, pool size = 5, active threads = 5, queued tasks = 3, completed tasks = 0]

这里看到显示被拒绝了，意思就是说原有定义的线程数不够用了，而我定义的又是拒绝策略，因为出现如上报错，

代码部分

package com.java.thread;

import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * @Description:
 * @Author: tutu-qiuxie
 * @Create: 2025/4/30 20:15
 */
public class ThreadPoolTest {

    private final static Logger logger= LoggerFactory.getLogger(ThreadPoolTest.class);

    public static void main(String[] args) {
        createThread();
    }

    public static void createThread() {
        ThreadPoolExecutor executor = new ThreadPoolExecutor(2,
                5,
                60L,
                TimeUnit.SECONDS,
                new ArrayBlockingQueue<>(3),
                new QiuXieThreadFactory(),
                new ThreadPoolExecutor.AbortPolicy());

        for (int i = 0; i < 10; i++) {
            final int taskId = i;
            executor.execute(() -> {
                try {
                    Thread.sleep(2000);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                logger.info(taskId + "," + Thread.currentThread().getName());
            });
        }
    }
}

　　

 很显然，这样是很不合理的，因为不能因为没有资源就赶人走你说是吧，当任务无人能接时，交给主线程做决定，简单来说就是排除大堂经理安排顾客

 

 看到没，这里就不报错了

代码部分

package com.java.thread;

import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * @Description:
 * @Author: tutu-qiuxie
 * @Create: 2025/4/30 20:15
 */
public class ThreadPoolTest {

    private final static Logger logger= LoggerFactory.getLogger(ThreadPoolTest.class);

    public static void main(String[] args) {
        createThread();
    }

    public static void createThread() {
        ThreadPoolExecutor executor = new ThreadPoolExecutor(2,
                5,
                60L,
                TimeUnit.SECONDS,
                new ArrayBlockingQueue<>(3),
                new QiuXieThreadFactory(),
                new ThreadPoolExecutor.CallerRunsPolicy());

        for (int i = 0; i < 10; i++) {
            final int taskId = i;
            executor.execute(() -> {
                try {
                    Thread.sleep(2000);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                logger.info(taskId + "," + Thread.currentThread().getName());
            });
        }
    }
}

　　但是也是有个问题的，如果顾客太多，大堂经理也是会崩溃的，那要咋办呢

咱可以动态调整服务人员嘛

代码部分

package com.java.thread;

import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * @Description:
 * @Author: tutu-qiuxie
 * @Create: 2025/4/30 20:15
 */
public class ThreadPoolTest {

    private final static Logger logger= LoggerFactory.getLogger(ThreadPoolTest.class);

    public static void main(String[] args) {
        createThread();
    }

    public static void createThread() {
        ThreadPoolExecutor executor = new ThreadPoolExecutor(2,
                5,
                60L,
                TimeUnit.SECONDS,
                new ArrayBlockingQueue<>(3),
                new QiuXieThreadFactory(),
                new ThreadPoolExecutor.CallerRunsPolicy());

        for (int i = 0; i < 100; i++) {
            final int taskId = i;
            executor.execute(() -> {
                try {
                    Thread.sleep(2000);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                logger.info(taskId + "," + Thread.currentThread().getName());
            });
            // 动态调整线程池大小
            if (i > 5) {
                executor.setCorePoolSize(4); // 增加核心线程数
                executor.setMaximumPoolSize(8); // 增加最大线程数
                logger.info("核心线程数:{},最大线程数:{}",executor.getCorePoolSize(),executor.getMaximumPoolSize());
            }
        }
    }
}

　　除了写死，还可以动态获取队列中任务数量

代码部分

package com.java.thread;

import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * @Description:
 * @Author: tutu-qiuxie
 * @Create: 2025/4/30 20:15
 */
public class ThreadPoolTest {

    private final static Logger logger= LoggerFactory.getLogger(ThreadPoolTest.class);

    public static void main(String[] args) {
        createThread();
    }

    public static void createThread() {
        ThreadPoolExecutor executor = new ThreadPoolExecutor(2,
                5,
                60L,
                TimeUnit.SECONDS,
                new ArrayBlockingQueue<>(3),
                new QiuXieThreadFactory(),
                new ThreadPoolExecutor.CallerRunsPolicy());

        for (int i = 0; i < 100; i++) {
            final int taskId = i;
            executor.execute(() -> {
                try {
                    Thread.sleep(2000);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                logger.info(taskId + "," + Thread.currentThread().getName());
            });
            // 动态调整线程池大小
            if (executor.getQueue().size() >= 3) {
                executor.setCorePoolSize(4); // 增加核心线程数
                executor.setMaximumPoolSize(8); // 增加最大线程数
                logger.info("核心线程数:{},最大线程数:{}",executor.getCorePoolSize(),executor.getMaximumPoolSize());
            }
        }
    }
}

　　

 pom依赖

<dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.32</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.12</version>
            <scope>runtime</scope>
        </dependency>