Dear Haskellers,

I am baffled by a strange bug (?) with threadDelay on Windows. It delays for less time than expected (500 seconds vs expected 24 hours), and is consistently reproducible on my system. Can someone have a look (need some patience, ~8 minutes waiting), just to be sure? I glanced around trac but didn't find any related issues.

How to reproduce:

module Main where

import Data.Time
import Control.Concurrent
import Control.Monad

main :: IO ()
main = do
_ <- forkIO thread
getLine >>= print -- Just to keep the main thread running

thread :: IO ()
thread = forever $ do
now <- getCurrentTime
print now
threadDelay 86400000000
print "done waiting"

Expected result:
2016-12-28 13:07:49.5113098 UTC
...
(next timing should be the next day 2016-12-29)

Actual result:
2016-12-28 13:07:49.5113098 UTC
"done waiting"
2016-12-28 13:16:10.2159485 UTC
"done waiting"
2016-12-28 13:24:30.8735845 UTC
"done waiting"
2016-12-28 13:32:51.5292203 UTC
...

System: Windows 7 Enterprise Service Pack 1, ghc 7.10.3

This seems specific to Windows, it doesn't appear on Debian 8. Help is appreciated!

Regards,
Hon

Rant: It has cost me significant debugging time! Please tell me I made a rookie mistake or misread the docs somewhere!