o Use nanosleep(2) to sleep exact amount of time till the next second,
not multiple of 1 second, which results in actual time to drift back
and forth every run within 1 second of the actual action has
been set for.

Suggested by: Ian Lepore

o Schedule the first run in 1 second after starting up, not on the
boundary of the next minute, which results in the every_second jobs
not being run.