Java 线程池newFixedThreadPool、newCachedThreadPool

newFixedThreadPool

@Slf4j
public class TheadPoolDemo {
    private static ThreadPoolExecutor threadPool = (ThreadPoolExecutor) Executors.newFixedThreadPool(10);

    public static void newFixedThreadPool() throws Exception {
        for (int i = 0; i < 2000000000; i++) {
            threadPool.execute(() ->
            {
                String payload = IntStream.rangeClosed(1, 90000000).mapToObj(__ -> "a").collect(Collectors.joining("")) + UUID.randomUUID().toString();
                try {
                    TimeUnit.HOURS.sleep(1);
                } catch (InterruptedException e) {
                }
                log.info(payload);
            });
        }
        threadPool.shutdown();
        threadPool.awaitTermination(1, TimeUnit.HOURS);
    }


}

运行一段时间后oom

原因分析

无界队列

果任务较多并且执行较慢的话，队列可能会快速积压，撑爆内存导致 OOM

newCachedThreadPool

 private static ThreadPoolExecutor threadPoolCached = (ThreadPoolExecutor) Executors.newCachedThreadPool();

    public static void newCachedThreadPool() throws Exception {
        for (int i = 0; i < 2000000000; i++) {
            threadPoolCached.execute(() ->
            {
                String payload = IntStream.rangeClosed(1, 90000000).mapToObj(__ -> "a").collect(Collectors.joining("")) + UUID.randomUUID().toString();
                try {
                    TimeUnit.HOURS.sleep(1);
                } catch (InterruptedException e) {
                }
                log.info(payload);
            });
        }
        threadPool.shutdown();
        threadPool.awaitTermination(1, TimeUnit.HOURS);
    }