有一个桌面应用程序使用Thread.sleep()来实现长(几分钟或几小时)延迟.这个应用程序从Windows XP到(至少)Windows 7都运行良好.应用程序计算未来需要做多少事情,然后点击Thread.sleep(msToWait).即使系统在等待期间恰好进入S3睡眠状态,这一直工作正常.
但是,从Windows 10开始,如果机器已经在S3中,则Thread.sleep()之后的代码不会“按时”执行.似乎机器开始执行代码“msToWait”加上机器进入S3的时间(现在不是100%肯定,但很可能).
早期版本的Windows没有表现出这种行为; Thread.sleep()之后的代码等待了适当的时间,而不管睡眠状态如何.
测试已在当前的JVM 1.7上进行.
这是Windows 10的错误吗?这是一个JVM错误吗?有解决方法吗?
附加数据:
开发了测试程序和程序.程序是运行程序,使机器休眠约一分钟,然后唤醒机器并等待程序完成.
如果这个程序在JVM版本:25.40-b25的Windows 10(报告为8)上运行,则会失败:
C:\Users\Tester\Downloads>SleepTester.exe
Wed Apr 01 10:47:35 PDT 2015 Using default number of minutes: 5
Wed Apr 01 10:47:35 PDT 2015 You can use "SleepTester -minutes 10" to have it sleep for 10 minutes, for example.
Wed Apr 01 10:47:35 PDT 2015 JVM Version: 25.40-b25 Windows Version: Windows 8
Wed Apr 01 10:47:35 PDT 2015 The program will Now wait for 5 minutes. Expect wrap-up at Wed Apr 01 10:52:35 PDT 2015
Wed Apr 01 10:53:38 PDT 2015 The system has come through the Thread.sleep(300000).
Wed Apr 01 10:53:38 PDT 2015 This should be a low number: 63589
Wed Apr 01 10:53:38 PDT 2015 This appears to be operating incorrectly...the expected sleep time has NOT been achieved.
Wed Apr 01 10:53:38 PDT 2015 Program is ending.
如果该进程在Windows 7上运行,则不会失败.
Wed Apr 01 17:12:18 EDT 2015 Java Runtime Version: 1.8.0_31-b13 JVM Version: 25.31-b07 Windows Version: Windows 7
Wed Apr 01 17:12:18 EDT 2015 The program will Now wait for 6 minutes. Expect wrap-up at Wed Apr 01 17:18:18 EDT 2015
Wed Apr 01 17:18:18 EDT 2015 The system has come through the Thread.sleep(360000).
Wed Apr 01 17:18:18 EDT 2015 This should be a low number: 0
Wed Apr 01 17:18:18 EDT 2015 Program is ending.
这是测试程序:
import java.util.Date;
public class SleepTester {
private static int mMinutes;
private static int mDefault = 5;
public static void main(String[] args) throws Exception {
for (int iArg = 0; iArg < args.length; ++iArg) {
if (args[iArg].equals("-minutes") && (iArg + 1) < args.length) {
mMinutes = Integer.parseInt(args[++iArg]);
}
}
if (mMinutes == 0) {
mMinutes = mDefault;
System.out.println(new Date() + " Using default number of minutes: " + mDefault);
System.out.println(new Date() + " You can use \"SleepTester -minutes 10\" to have it sleep for 10 minutes, for example.");
}
System.out.println(new Date() + " Java Runtime Version: " + System.getProperty("java.runtime.version") + " JVM Version: " + System.getProperty("java.vm.version") + " Windows Version: " + System.getProperty("os.name"));
long msDelay = mMinutes * 60 * 1000;
long wakePoint = new Date().getTime() + msDelay;
System.out.println(new Date() + " The program will Now wait for " + mMinutes + " minutes. Expect wrap-up at " + new Date(wakePoint));
Thread.sleep(msDelay); // If the machine goes into S3 during this interval, it should not matter, as long as it's awake when it fires.
System.out.println(new Date() + " The system has come through the Thread.sleep(" + msDelay + "). ");
long msAccuracy = Math.abs(new Date().getTime() - wakePoint);
System.out.println(new Date() + " This should be a low number: " + msAccuracy);
if (msAccuracy > 1000) System.out.println(new Date() + " This appears to be operating incorrectly...the expected sleep time has NOT been achieved.");
System.out.println(new Date() + " Program is ending.");
}
}
我意识到我可以尝试各种其他方法来睡觉,但我认为,因为我经历并记录了这一点,我会在尝试其他事情之前在此发布.
附加信息:此故障似乎也出现在Windows 8中(但不是7或更早).
解决方法:
这是预期的有效行为. documentation是非常明确的,说明:
these sleep times are not guaranteed to be precise, because they are limited by the facilities provided by the underlying OS.
和:
In any case, you cannot assume that invoking
sleep
will suspend the thread for precisely the time period specified.