java线程池使用场景及一些建议

private static final ExecutorService executor = new ThreadPoolExecutor(
        2,
        4,
        1L,
        TimeUnit.MINUTES,
        new LinkedBlockingQueue<>(100),
        new ThreadFactoryBuilder().setNameFormat("common-pool-%d").build(),
        new ThreadPoolExecutor.CallerRunsPolicy());

public class ThreadPoolMonitor {
    private final static Logger log = LoggerFactory.getLogger(ThreadPoolMonitor.class);
    private static final ThreadPoolExecutor threadPool = new ThreadPoolExecutor(2, 4, 0,
            TimeUnit.SECONDS, new LinkedBlockingQueue<>(100),
            new ThreadFactoryBuilder().setNameFormat("my_thread_pool_%d").build());
    public static void main(String[] args) {
        log.info("Pool Size: " + threadPool.getPoolSize());
        log.info("Active Thread Count: " + threadPool.getActiveCount());
        log.info("Task Queue Size: " + threadPool.getQueue().size());
        log.info("Completed Task Count: " + threadPool.getCompletedTaskCount());
    }
}

package com.springboot.micrometer.monitor;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import io.micrometer.core.instrument.Metrics;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import java.util.stream.IntStream;
@Component
public class ThreadPoolMonitor {
    private static final ThreadPoolExecutor threadPool = new ThreadPoolExecutor(4, 8, 0,
            TimeUnit.SECONDS, new LinkedBlockingQueue<>(100),
            new ThreadFactoryBuilder().setNameFormat("my_thread_pool_%d").build(), new ThreadPoolExecutor.DiscardOldestPolicy());
    /**
     * 活跃线程数
     */
    private AtomicLong activeThreadCount = new AtomicLong(0);
    /**
     * 队列任务数
     */
    private AtomicLong taskQueueSize = new AtomicLong(0);
    /**
     * 完成任务数
     */
    private AtomicLong completedTaskCount = new AtomicLong(0);
    /**
     * 线程池中当前线程的数量
     */
    private AtomicLong poolSize = new AtomicLong(0);
    @PostConstruct
    private void init() {
        /**
         * 通过micrometer API完成统计
         *
         * gauge最典型的使用场景就是统计：list、Map、线程池、连接池等集合类型的数据
         */
        Metrics.gauge("my_thread_pool_active_thread_count", activeThreadCount);
        Metrics.gauge("my_thread_pool_task_queue_size", taskQueueSize);
        Metrics.gauge("my_thread_pool_completed_task_count", completedTaskCount);
        Metrics.gauge("my_thread_pool_size", poolSize);
        // 模拟线程池的使用
        new Thread(this::runTask).start();
    }
    private void runTask() {
        // 每5秒监控一次线程池的使用情况
        monitorThreadPoolState();
        // 模拟任务执行
        IntStream.rangeClosed(0, 500).forEach(i -> {
            // 每500毫秒，执行一个任务
            try {
                TimeUnit.MILLISECONDS.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            // 每个处理一个任务耗时5秒
            threadPool.submit(() -> {
                try {
                    TimeUnit.MILLISECONDS.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
        });
    }
    private void monitorThreadPoolState() {
        Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate(() -> {
            activeThreadCount.set(threadPool.getActiveCount());
            taskQueueSize.set(threadPool.getQueue().size());
            poolSize.set(threadPool.getPoolSize());
            completedTaskCount.set(threadPool.getCompletedTaskCount());
        }, 0, 5, TimeUnit.SECONDS);
    }
}