具有corePoolSize = 0的ScheduledThreadPoolExecutor会在一个CPU核心上导致100％负载 [英] ScheduledThreadPoolExecutor with corePoolSize = 0 causes 100% load on one CPU core

问题描述

给出以下 <的配置code> ScheduledThreadPoolExecutor ，每五秒运行一次简单的任务：

Given is the following configuration of a ScheduledThreadPoolExecutor that runs a simple task every five seconds:

int corePoolSize = 0;
ScheduledExecutorService executor = new ScheduledThreadPoolExecutor(corePoolSize);

Runnable task = () -> System.out.println("XXX");
executor.scheduleAtFixedRate(task, 5, 5, TimeUnit.SECONDS);

在Oracle JRE上 1.8.0_66 有一个由 ScheduledThreadPoolExecutor 创建的线程，它不断导致一个CPU核心100％负载。
调查线程转储显示以下stacktrace：

On Oracle JRE 1.8.0_66 there’s one thread created by the ScheduledThreadPoolExecutor that constantly causes 100% load on one CPU core. Investigating the thread dump reveals the following stacktrace:

"pool-1-thread-1" - Thread t@10
   java.lang.Thread.State: RUNNABLE
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.poll(ScheduledThreadPoolExecutor.java:809)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1066)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

使用 corePoolSize = 1 池中仍有一个线程。但是，该线程基本上始终处于状态 TIMED_WAITING 并因此空闲。

With corePoolSize = 1 there is still one thread in the pool. However, the thread is basically always in state TIMED_WAITING and thus idle.

是否行为 ScheduledThreadPoolExecutor with corePoolSize = 0 已知功能，未经验证的错误配置甚至是错误？

Is the behavior of ScheduledThreadPoolExecutor with corePoolSize = 0 a known feature, an unvalidated misconfiguration or even a bug?

推荐答案

看起来你已经点击 JDK已在Java 9中修复的-8129861 。它也可能与 JDK有关-8022642 。

It looks like you have hit JDK-8129861 that has been fixed in Java 9. It may also be related to JDK-8022642.

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