Thread.sleep等待超过预期 [英] Thread.sleep waits more than expected

问题描述

以下代码：

long msBefore = System.currentTimeMillis();
//Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
try
{Thread.sleep(200);
} catch (InterruptedException e){}
System.out.println("Time: " + (System.currentTimeMillis() - msBefore));

打印：

Time: 578
Time: 594
Time: 625
Time: 640
Time: 641
Time: 609
Time: 625
Time: 625
Time: 610
Time: 609
Time: 625
Time: 625
Time: 422
Time: 625
Time: 594
Time: 609
Time: 625
Time: 594
Time: 594
Time: 625

问题出在哪里？

推荐答案

我要求每秒发送n条消息，我认为等待/通知不合适，对吗？

I have a requirement to send n messages per second, I think wait/notify don't fit, correct?

如果您有严格的时间要求，那么您将需要使用实时Java 实施。主流SE和ME Java实现不适合硬实时应用。

If you have a hard timing requirement, then you are going to need to use a real-time Java implementation. Mainstream SE and ME Java implementations are not suitable for hard realtime applications.

您可以使用各种技巧来满足大多数时间的要求......但是如果您的应用程序/系统过载，您可能会开始错过所需的消息率。

There are various tricks you can use to meet such requirements "most of the time" ... but if your application / system gets overloaded you are liable start to missing the required message rate.

真正的问题不在于计时器的准确性，而是非事实-realtime调度程序不会（也不能）保证在计时器到期后安排线程运行。

Th real problem is not the accuracy of the timers, but the fact that a non-realtime scheduler won't (and can't) guarantee to schedule the thread to run as soon as the timer expires.

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