setTimeout delayed when sleeping on Windows

[seishun]

• Version: v6.1.0 and master
• Platform: Windows 10 64-bit
• Subsystem: timers

Testcase:

console.log(Date());
setTimeout(function() {
    console.log(Date());
}, 20000);

When running it normally, the result is as expected:

Sat May 14 2016 23:20:36 GMT+0300 (FLE Daylight Time)
Sat May 14 2016 23:20:56 GMT+0300 (FLE Daylight Time)

However, if you do the following:

1. Start the script.
2. Put the computer to sleep ASAP.
3. Resume after 10 seconds.

The timeout fires not after the remaining 10 seconds, but after ~20 seconds:

Sat May 14 2016 23:22:14 GMT+0300 (FLE Daylight Time)
Sat May 14 2016 23:22:45 GMT+0300 (FLE Daylight Time)

I've asked on IRC and people say that this doesn't happen on Linux. That is, the callback is not delayed unless it would have occurred during sleep, in which case it's fired as soon as the computer wakes up.

[bnoordhuis]

Libuv on Linux uses CLOCK_BOOTTIME when available (kernel >= 2.6.39). Windows doesn't have an equivalent with good enough precision, AFAIK.

[seishun]

Doesn't libuv on Linux simply use the timeout parameter of epoll_wait, just like it does on Windows with IOCP?

[bnoordhuis]

I take back what I said. I thought CLOCK_BOOTTIME was the clock source for timers but it's the clock source for uptime calculations only.

[seishun]

Anyway, apparently GetQueuedCompletionStatus doesn't advance the timeout while sleeping. Testcase:

#include "Windows.h"
#include <ctime>
#include <iostream>
#include <iomanip>

int main()
{
  auto whatever = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);
  OVERLAPPED_ENTRY entries[10];

  auto t = std::time(nullptr);
  auto tm = *std::localtime(&t);
  std::cout << std::put_time(&tm, "%d-%m-%Y %H-%M-%S") << std::endl;

  ULONG bleh;
  GetQueuedCompletionStatusEx(whatever, entries, 10, &bleh, 20000, FALSE);

  // try sleeping here

  t = std::time(nullptr);
  tm = *std::localtime(&t);
  std::cout << std::put_time(&tm, "%d-%m-%Y %H-%M-%S") << std::endl;

}

I'm not sure if there is an alternative that works properly. Pinging @piscisaureus

[seishun]

Well what do you know. I cannot reproduce this on Windows 7. Either I've discovered an obscure bug in Windows 10, or there's something funky going on with my Windows 10 machine.

[seishun]

@nodejs/collaborators @nodejs/platform-windows if anyone could try to reproduce this and post their results that would be great.

[iakat]

I can reproduce this issue on my desktop and laptop; both running Windows 10 (Pro & Enterprise), on v6.1.0.

[seishun]

Pinging @orangemocha

<@saghul> maybe @ orangemocha, maybe he can ask someone on the Windows team at Microsoft

[orangemocha]

I don't know the answer from the top of my head, but I'll follow up on this one. Thank you for bringing it to my attention.

[seishun]

@orangemocha have you found out anything?

[orangemocha]

I haven't investigated it yet, sorry. Bumping it.