Indeed, you would have issues with file stamps changing on Windows NT+ if the file system is FAT. However, this is not because the system time moves forth and back, but because FAT time stamps get reinterpreted according to the current time zone, not according to the time zone in force when the file was created (as NT tries to convert the FAT time stamps to UTC). On NTFS, this is not an issue, as NTFS file stamps are in UTC already (units of 100ns since Jan 1, 1601).

So indeed, the submitter complains that Condition.wait doesn't time out correctly if the system clock is changed while the wait occurs. I think it is reasonable to make this complaint, however, I don't like to the patch proposed, and I do think this can't really be fixed without the help of the operating system (so I wouldn't mind if it was unfixed on systems that don't help). The point is that .wait() really takes a duration, not a time stamp, for timeout, and we should honor that. The duration should expire after the given amount of physical time has passed, independent of the system clock. As I said, one way to implement this would be to use a monotonic clock if the system has one.