SpringBoot创建线程池的六种方式小结

/**
 * 自定义线程池
 * <p>
 * 优点：可以自定义参数
 * </p>
 */
@Test
public void newThreadPoolExecutor() {
    ThreadPoolExecutor executor = new ThreadPoolExecutor(
            // 核心线程数
            3,
            // 最大线程数
            5,
            // 空闲线程最大存活时间
            60L,
            // 空闲线程最大存活时间单位
            TimeUnit.SECONDS,
            // 等待队列及大小
            new ArrayBlockingQueue<>(100),
            // 创建新线程时使用的工厂
            Executors.defaultThreadFactory(),
            // 当线程池达到最大时的处理策略
//                new ThreadPoolExecutor.AbortPolicy()          // 抛出RejectedExecutionHandler异常
            new ThreadPoolExecutor.CallerRunsPolicy()       // 交由调用者的线程执行
//                new ThreadPoolExecutor.DiscardOldestPolicy()  // 丢掉最早未处理的任务
//                new ThreadPoolExecutor.DiscardPolicy()        // 丢掉新提交的任务
    );

    // 总共5个任务
    for (int i = 1; i <= 5; i++) {
        int taskIndex = i;
        executor.execute(() -> {
            log.info("线程 " + Thread.currentThread().getName() + " 正在执行任务 " + taskIndex);

            // 每个任务耗时1秒
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });
    }

    executor.shutdown();
}

/**
 * 固定大小线程池
 * <p>
 * 优点：当任务执行较快，且任务较少时使用方便
 * </p>
 * <p>
 * 风险：当处理较慢时，等待队列的任务堆积会导致OOM
 * </p>
 */
@Test
public void newFixThreadPool() {
    // 3个固定线程
    ExecutorService executorService = Executors.newFixedThreadPool(3);

    // 总共5个任务
    for (int i = 1; i <= 5; i++) {
        int taskIndex = i;
        executorService.execute(() -> {
            log.info("线程 " + Thread.currentThread().getName() + " 正在执行任务 " + taskIndex);

            // 每个任务耗时1秒
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });
    }

    executorService.shutdown();
}

/**
 * Creates a thread pool that reuses a fixed number of threads
 * operating off a shared unbounded queue.  At any point, at most
 * {@code nThreads} threads will be active processing tasks.
 * If additional tasks are submitted when all threads are active,
 * they will wait in the queue until a thread is available.
 * If any thread terminates due to a failure during execution
 * prior to shutdown, a new one will take its place if needed to
 * execute subsequent tasks.  The threads in the pool will exist
 * until it is explicitly {@link ExecutorService#shutdown shutdown}.
 *
 * @param nThreads the number of threads in the pool
 * @return the newly created thread pool
 * @throws IllegalArgumentException if {@code nThreads <= 0}
 */
public static ExecutorService newFixedThreadPool(int nThreads) {
    return new ThreadPoolExecutor(nThreads, nThreads,
                                  0L, TimeUnit.MILLISECONDS,
                                  new LinkedBlockingQueue<Runnable>());
}

/**
 * 单一线程池
 * <p>
 * 优势：保存任务按照提交的顺序执行
 * </p>
 * <p>
 * 风险：当处理较慢时，等待队列的任务堆积会导致OOM
 * </p>
 */
@Test
public void newSingleThreadExecutor() {
    // 1个线程
    ExecutorService executor = Executors.newSingleThreadExecutor();

    // 总共5个任务
    for (int i = 1; i <= 5; i++) {
        int taskIndex = i;
        executor.execute(() -> {
            log.info("线程 " + Thread.currentThread().getName() + " 正在执行任务 " + taskIndex);

            // 每个任务耗时1秒
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });
    }

    executor.shutdown();
}

/**
 * Creates an Executor that uses a single worker thread operating
 * off an unbounded queue. (Note however that if this single
 * thread terminates due to a failure during execution prior to
 * shutdown, a new one will take its place if needed to execute
 * subsequent tasks.)  Tasks are guaranteed to execute
 * sequentially, and no more than one task will be active at any
 * given time. Unlike the otherwise equivalent
 * {@code newFixedThreadPool(1)} the returned executor is
 * guaranteed not to be reconfigurable to use additional threads.
 *
 * @return the newly created single-threaded Executor
 */
public static ExecutorService newSingleThreadExecutor() {
    return new FinalizableDelegatedExecutorService
        (new ThreadPoolExecutor(1, 1,
                                0L, TimeUnit.MILLISECONDS,
                                new LinkedBlockingQueue<Runnable>()));
}

/**
 * 共享线程池
 * <p>
 * 优势：当在某一时间段内任务较多，且执行较快时方便使用
 * </p>
 * <p>
 * 风险：当处理较慢时，会创建大量的线程
 * </p>
 */
@Test
public void newCachedThreadPool() {
    ExecutorService executor = Executors.newCachedThreadPool();

    // 总共5个任务
    for (int i = 1; i <= 5; i++) {
        int taskIndex = i;
        executor.execute(() -> {
            log.info("线程 " + Thread.currentThread().getName() + " 正在执行任务 " + taskIndex);

            // 每个任务耗时1秒
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        });
    }

    executor.shutdown();
}

/**
 * Creates a thread pool that creates new threads as needed, but
 * will reuse previously constructed threads when they are
 * available.  These pools will typically improve the performance
 * of programs that execute many short-lived asynchronous tasks.
 * Calls to {@code execute} will reuse previously constructed
 * threads if available. If no existing thread is available, a new
 * thread will be created and added to the pool. Threads that have
 * not been used for sixty seconds are terminated and removed from
 * the cache. Thus, a pool that remains idle for long enough will
 * not consume any resources. Note that pools with similar
 * properties but different details (for example, timeout parameters)
 * may be created using {@link ThreadPoolExecutor} constructors.
 *
 * @return the newly created thread pool
 */
public static ExecutorService newCachedThreadPool() {
    return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
                                  60L, TimeUnit.SECONDS,
                                  new SynchronousQueue<Runnable>());
}

/**
 * 定时线程池
 * <p>
 * 优点：可以定时执行某些任务
 * </p>
 * <p>
 * 风险：当处理较慢时，等待队列的任务堆积会导致OOM
 * </p>
 */
@Test
public void newScheduledThreadPool() {
//        // 单一线程
//        ExecutorService executor = Executors.newSingleThreadScheduledExecutor();
    // 指定核心线程数
    ScheduledExecutorService executor = Executors.newScheduledThreadPool(3);

    executor.schedule(() -> {
        log.info("3秒后开始执行，以后不再执行");

        // 每个任务耗时1秒
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }, 3, TimeUnit.SECONDS);
//
//        executor.scheduleAtFixedRate(() -> {
//            log.info("3秒后开始执行，以后每2秒执行一次");
//
//            // 每个任务耗时1秒
//            try {
//                TimeUnit.SECONDS.sleep(1);
//            } catch (InterruptedException e) {
//                e.printStackTrace();
//            }
//        }, 3, 2, TimeUnit.SECONDS);
//
//        executor.scheduleWithFixedDelay(() -> {
//            log.info("3秒后开始执行，以后延迟2秒执行一次");
//
//            // 每个任务耗时1秒
//            try {
//                TimeUnit.SECONDS.sleep(1);
//            } catch (InterruptedException e) {
//                e.printStackTrace();
//            }
//        }, 3, 2, TimeUnit.SECONDS);
}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.task.TaskExecutor;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.ThreadPoolExecutor;

/**
 * 自定义线程池配置类
 *
 * @author CL
 */
@Configuration
public class TaskExecutorConfig {

    /**
     * 自定义任务执行器
     *
     * @return {@link TaskExecutor}
     */
    @Bean
    public TaskExecutor taskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        // 核心线程数，默认1
        int corePoolSize = Runtime.getRuntime().availableProcessors();
        executor.setCorePoolSize(corePoolSize);
        // 最大线程数，默认Integer.MAX_VALUE
        executor.setMaxPoolSize(corePoolSize * 2 + 1);
        // 空闲线程最大存活时间，默认60秒
        executor.setKeepAliveSeconds(3);
        // 等待队列及大小，默认Integer.MAX_VALUE
        executor.setQueueCapacity(500);
        // 线程的名称前缀，默认该Bean名称简写：org.springframework.util.ClassUtils.getShortName(java.lang.Class<?>)
        executor.setThreadNamePrefix("custom-thread-");
        // 当线程池达到最大时的处理策略，默认抛出RejectedExecutionHandler异常
//        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());         // 抛出RejectedExecutionHandler异常
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());    // 交由调用者的线程执行
//        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardOldestPolicy()); // 丢掉最早未处理的任务
//        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy());       // 丢掉新提交的任务
        // 等待所有任务结束后再关闭线程池，默认false
        executor.setWaitForTasksToCompleteOnShutdown(true);
        // 等待所有任务结束最长等待时间，默认0毫秒
        executor.setAwaitTerminationSeconds(10);
        // 执行初始化
        executor.initialize();
        return executor;
    }

}

/**
 * 示例Service
 *
 * @author CL
 */
public interface DemoService {

    /**
     * 示例方法
     *
     * @return {@link String}
     */
    void demo();

}

import lombok.extern.slf4j.Slf4j;
import org.springframework.core.task.TaskExecutor;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;


/**
 * 示例Service实现
 *
 * @author CL
 */
@Slf4j
@Service
public class DemoServiceImpl implements DemoService {

    @Resource
    private TaskExecutor taskExecutor;

    /**
     * 示例方法
     */
    @Override
    public void demo() {
        taskExecutor.execute(() -> {
            log.info("线程 " + Thread.currentThread().getName() + " 正在执行Service中的方法");
        });
    }

}

import lombok.extern.slf4j.Slf4j;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.stereotype.Component;

/**
 * 示例异步任务
 *
 * @author CL
 */
@Slf4j
@Component
@EnableAsync
public class DemoAsync {

    /**
     * 示例方法
     */
    @Async(value = "taskExecutor")
    public void demo() {
        log.info("线程 " + Thread.currentThread().getName() + " 正在执行Async中的方法");
    }

}

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.TaskScheduler;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadPoolExecutor;

/**
 * 自定义定时任务调度配置类
 *
 * @author CL
 */
@Configuration
public class SheduledConfig implements SchedulingConfigurer {

    /**
     * 配置定时任务
     *
     * @param scheduledTaskRegistrar 配置任务注册器
     */
    @Override
    public void configureTasks(ScheduledTaskRegistrar scheduledTaskRegistrar) {
        scheduledTaskRegistrar.setScheduler(taskScheduler());

//        // 第二种方式
//        scheduledTaskRegistrar.setScheduler(scheduledExecutorService());
    }

    /**
     * 自定义任务调度器
     *
     * @return {@link TaskScheduler}
     */
    @Bean
    public TaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler executor = new ThreadPoolTaskScheduler();
        executor.setPoolSize(5);
        executor.setThreadNamePrefix("custom-scheduler-");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.initialize();
        return executor;
    }

//    /**
//     * 自定义任务线程池
//     *
//     * @return {@link ScheduledExecutorService}
//     */
//    @Bean
//    public ScheduledExecutorService scheduledExecutorService() {
//        return Executors.newScheduledThreadPool(5);
//    }

}

import com.c3tones.async.DemoAsync;
import com.c3tones.service.DemoService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

/**
 * 示例Controller
 *
 * @author CL
 */
@Slf4j
@RestController
public class DemoController {

    @Resource
    private DemoService demoService;

    @Resource
    private DemoAsync demoAsync;

    /**
     * Service示例方法
     *
     * @return {@link String}
     */
    @RequestMapping("/service")
    public void service() {
        log.info("Service示例方法开始执行");
        demoService.demo();
        log.info("Service示例方法结束执行");
    }

    /**
     * 异步示例方法
     *
     * @return {@link String}
     */
    @RequestMapping("/async")
    public void async() {
        log.info("异步示例方法开始执行");
        demoAsync.demo();
        log.info("异步示例方法结束执行");
    }

}

curl http://127.0.0.1:8080/service

curl http://127.0.0.1:8080/async

import lombok.extern.slf4j.Slf4j;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

/**
 * 示例定时任务
 *
 * @author CL
 */
@Slf4j
@Component
@EnableScheduling
public class DemoScheduled {

    /**
     * 示例方法
     */
    @Scheduled(cron = "0/3 * * * * ? ")
    public void demo() {
        log.info("线程 " + Thread.currentThread().getName() + " 正在执行Scheduled中的方法");
    }

}