[LEAPSECS] Longer horizon

Michael Spacefalcon msokolov at ivan.Harhan.ORG
Tue Jul 10 21:42:51 EDT 2012

Daniel R. Tobias <dan at tobias.name> wrote:

> Actually, from what I've seen and heard about this year's crop of

> bugs, server crashes, etc., relating to the leap second, the big

> problems come when the developers know and care just enough to be

> dangerous.


> If you take the total dumbass approach to leap seconds, like you

> don't even know they exist, or pretend they don't exist even though

> you've heard of them, then in most cases your hardware and software

> will muddle through just fine. It might wind up a second off after

> the leap second happens, but that will just be an additional

> one-second delta added (or subtracted) on to whatever other delta

> might exist due to normal clock drift, which will eventually get

> corrected (either in an abrupt jump or smoothed out, depending on the

> system software) when the system next polls whatever external time

> source it periodically syncs to (if it does this at all).

That's exactly what happens on my current systems.

> It's only when you actually attempt to get the system to account for

> the leap second immediately and precisely when it happens that you

> end up having to code in something convoluted that only runs every

> couple of years, with all the potential to screw it up and cause a

> major crash of some sort. Probably only less than 1/10 of 1 percent

> of systems actually need this degree of precision, so the other 99.9%

> are best off not even trying to do anything special for the leap

> second,

Finally, a voice of reason - that's exactly how I feel. Nice to hear
that there is at least one other person who agrees with me, at least
in this regard.

> though some defensive programming to keep from crashing if

> fed something like "23:59:60" from a remote site would be desirable.

Of course. However, this issue would only exist if the external time
input is an ASCII string or struct in HH:MM:SS format, and I have yet
to see a system that uses such formats for time interchange. All
systems that I'm familiar with use time-as-a-real-number formats
instead: JD, MJD, time_t, NTP, etc.


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