[LEAPSECS] LOD reaches 0 s/d

[jimlux]

On 11/12/20 3:45 PM, Poul-Henning Kamp wrote:
> --------
> 
>>      predicts that d(UT2)/d(TAI) = 1 after 2021-11-13, ie
>>      the rates of UTT2 and TAI are expected to agree for the
>>      next year. This has never happened since 1961. We may
>>      not need to abolish leap seconds for quite a while.
> 
> Unless of course we get close enough to a negative one, that people
> are *really* going to freak out.
> 
> Hands in the air:  Who here besides Warner and me has ever tried to
> test handling of negative leap-seconds ?
> 

not exactly leap seconds, but I had a system that ingested time from two 
sources that were nominally synced, and one slipped behind -  it was a 
gruesome disaster. Time going backwards creates ALL sorts of problems 
with log files and locking schemes and telemetry decoding/plotting that 
assume that time is monotonically increasing. (we leave, aside, the 
whole daylight time issue - that's a "print formatting of time values" 
thing.


It fills me with great trepidation if clock time were ever to go 
backwards.  I think what would happen is that people would hack it and 
have it sort of run slowly over some seconds, while maintaining 
monotonicity.  And then create tiger teams to fix it when someone else 
did it differently, and your financial system ingested transactions that 
appeared to end before they started.