package test;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.RandomUtils;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

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

/**
 * @title 線程池異步線程中再次獲取線程池資源的問(wèn)題
 * @author Xingbz
 * @description
 *  記;
 *
 *  究其原因在于:
 *      
 * @createDate 2020-7-17
 */
@Slf4j
public class TestWork {

    private static final ThreadPoolTaskExecutor EXECUTOR;

    static {
        EXECUTOR = myExecutor();
    }

    /** 初始化線程池 */
    public static ThreadPoolTaskExecutor myExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        // 核心線程數(shù)
        executor.setCorePoolSize(5);
        // 最大線程數(shù)
        executor.setMaxPoolSize(20);
        // 排隊(duì)任務(wù)隊(duì)列
        executor.setQueueCapacity(100);
        // 線程名稱前綴
        executor.setThreadNamePrefix("異步線程-");
        // 隊(duì)列滿后拒絕策略
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        // 線程最大回收時(shí)間
        executor.setKeepAliveSeconds(100);
        // 初始化線程
        executor.initialize();
        return executor;
    }

    /** 模擬測(cè)試 */
    public static void main(String[] args) throws Exception {
        // 主任務(wù)數(shù)量
        int mainJobNum = 20;

        CountDownLatch mainDownLatch = new CountDownLatch(mainJobNum);

        for (int i = 0; i < mainJobNum; i++) {
            // 主任務(wù)編號(hào), 方便區(qū)分
            int index = i + 1;

            // 模擬每1秒開(kāi)始一個(gè)主任務(wù)
            TimeUnit.SECONDS.sleep(1);

            EXECUTOR.submit(() -> {
                try {
                    log.debug("\t執(zhí)行主任務(wù)" + index);

                    // 每個(gè)主任務(wù)隨機(jī)包含N個(gè)子任務(wù), 再異步調(diào)用線程池資源處理
                    int subJobNum = RandomUtils.nextInt(2, 3);
                    subJobWorkAsync(subJobNum, index);
                } finally {
                    mainDownLatch.countDown();
                }
            });
        }

        mainDownLatch.await();
        EXECUTOR.shutdown();
        log.info("完成所有任務(wù) > > >");
    }

    /** 異步執(zhí)行子任務(wù) */
    private static void subJobWorkAsync(int subJobNum, int index) {
        CountDownLatch subDownLatch = new CountDownLatch(subJobNum);
        for (int j = 0; j < subJobNum; j++) {
            EXECUTOR.submit(() -> {
                try {
                    log.warn("\t\t\t執(zhí)行一個(gè)" + index + "的子任務(wù)");
                    // 每個(gè)子任務(wù)模擬耗時(shí)
                    TimeUnit.SECONDS.sleep(3);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    subDownLatch.countDown();
                }
            });
        }

        try {
            subDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}