Got it -- fair enough.

We deploy so often where I work (a couple of times a week at least) that 104 days seems like an eternity. But I can see where for a very stable file server or something you might well run it that long without deploying. Then again, why are you doing performance tuning on a "very stable server"?

-Ben

On Mon, Oct 16, 2017 at 11:58 AM, Guido van Rossum <guido@python.org> wrote:

On Mon, Oct 16, 2017 at 8:37 AM, Ben Hoyt <benhoyt@gmail.com> wrote:
I've read the examples you wrote here, but I'm struggling to see what the real-life use cases are for this. When would you care about *both* very long-running servers (104 days+) and nanosecond precision? I'm not saying it could never happen, but would want to see real "experience reports" of when this is needed.

A long-running server might still want to log precise *durations* of various events. (Durations of events are the bread and butter of server performance tuning.) And for this it might want to use the most precise clock available, which is perf_counter(). But if perf_counter()'s epoch is the start of the process, after 104 days it can no longer report ns precision due to float rounding (even though the internal counter does not lose ns).

--
--Guido van Rossum (python.org/~guido)