[Python-ideas] Add time.time_ns(): system clock with nanosecond resolution

[Serhiy Storchaka]

13.10.17 17:12, Victor Stinner пише:
> I would like to add new functions to return time as a number of
> nanosecond (Python int), especially time.time_ns().
> 
> It would enhance the time.time() clock resolution. In my experience,
> it decreases the minimum non-zero delta between two clock by 3 times,
> new "ns" clock versus current clock: 84 ns (2.8x better) vs 239 ns on
> Linux, and 318 us (2.8x better) vs 894 us on Windows, measured in
> Python.
> 
> The question of this long email is if it's worth it to add more "_ns"
> time functions than just time.time_ns()?
> 
> I would like to add:
> 
> * time.time_ns()
> * time.monotonic_ns()
> * time.perf_counter_ns()
> * time.clock_gettime_ns()
> * time.clock_settime_ns()
> 
> time(), monotonic() and perf_counter() clocks are the 3 most common
> clocks and users use them to get the best available clock resolution.
> clock_gettime/settime() are the generic UNIX API to access these
> clocks and so should also be enhanced to get nanosecond resolution.

I don't like the idea of adding a parallel set of functions.

In the list of alternatives in PEP 410 there is no an idea about fixed 
precision float type with nanoseconds precision. It can be implemented 
internally as a 64-bit integer, but provide all methods required for 
float-compatible number. It would be simpler and faster than general 
Decimal.