java | 固定大小的线程池

newFixedThreadPool。

public static ExecutorService newFixedThreadPool(int nThreads) {
        return new ThreadPoolExecutor(nThreads, nThreads,
                                      0L, TimeUnit.MILLISECONDS,
                                      new LinkedBlockingQueue<Runnable>());
    }

特点

• 核心线程数 == 最大线程数「没有救急线程」
• 阻塞队列是无界的，可以放任意数量的任务

适用于任务量已知，相对耗时的任务

package com.redisc;

import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

@Slf4j(topic = "c.Test")
public class Run {

    public static void main(String[] args) {
        ExecutorService pool = Executors.newFixedThreadPool(2);
        pool.execute(() -> {
            log.debug("1");
        });
        pool.execute(() -> {
            log.debug("2");
        });
        pool.execute(() -> {
            log.debug("3");
        });
    }
}

输出

23:15:59.050 [pool-1-thread-1] DEBUG c.Test - 1
23:15:59.050 [pool-1-thread-2] DEBUG c.Test - 2
23:15:59.057 [pool-1-thread-1] DEBUG c.Test - 3