[time-nuts] Leap second to be introduced at midnight UTC December 31 this year

Hal Murray hmurray at megapathdsl.net
Wed Jul 20 04:05:59 EDT 2016

gem at rellim.com said:
> Yes, I know the problem being solved.  Like today, the leap second being
> broadcast sooner than ntpd expects, so it picks the wrong month. 

Do you know of any ntp servers that have picked the wrong month?

gem at rellim.com said:
>> I don't think there is anything in the core of ntpd that restricts
>> leap seconds to Jun/Dec.  If there was, it would have filtered out
>> the above problem.
> How about this: 
> ntpd/refclock_hpgps.c, line 544:

I wasn't considering refclocks to be "core" in that context.  Got a better 

Have you found any similar code that isn't in one of the refclocks?

gem at rellim.com said:
> 20 years?  My house is 40 years old.  In an IoT world people would like to
> not throw away capital equipment every decade. 

Your house gets a new roof occasionally.  The IoT world hasn't figured out 
how to handle firmware updates and/or people haven't adapted to throwing out 
gear that looks OK physically but has bugs, especially if the bugs don't 
break the main function of the device.

gem at rellim.com said:
> gpsd filters out all but June and December.  So sort of cleanly, but clearly
> work needed.  ...

The sort of "cleanly" I had in mind would be at the project management level. 
 Handwave.  Each project should keep track of the assumptions in their code 
that may not be correct many years in the future.  That list should be 
reviewed occasionally, say every year or few years.

It also has to be documented in a way that downstream users know what they 
are getting involved with.  This is a good example.  Tom is arguing for 
do-it-right according to the specs.  I'm arguing for defensive programming 
since we have already seen bugs in other gear.  If you were packaging ntpd 
into a box which would you want?  Will your box last long enough to see a 
leap second in Mar or Sep?  Is your box going to connect to old/buggy gear?  
Does your startup have enough funding to consider issues like this, or people 
smart enough to understand the tangle?

These are my opinions.  I hate spam.

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