Use the monotonic clock to measure time elapsed

[jtilahun]

For measuring elapsed time, one should use a monotonic clock instead of the system clock because the system clock can go backwards in time, whereas a monotonic clock is guaranteed to be non-decreasing.

[dougthor42]

Is there particular reason to use monotonic instead of perf_counter?

Also, would you rather use monotonic_ns (or perf_counter_ns) to avoid floating point errors?

[jtilahun]

Is there particular reason to use monotonic instead of perf_counter?

Per PEP 418, monotonic is suitable for implementing a timeout in a program. perf_counter does exist as well, but perf_counter is intended for use in performance and benchmarking contexts.

Also, would you rather use monotonic_ns (or perf_counter_ns) to avoid floating point errors?

Are floating point errors a real concern here? If floating point errors are a true concern here, then it's possible to use the corresponding *_ns function to mitigate that concern.

[dougthor42]

Per PEP 418 ...

Ah, thanks I didn't know that!

Are floating point errors a real concern here?

Unlikely. I just tend to use *_ns by default these days.

I'm not officially associated with pyvisa so feel free to ignore me 😁. For what it's worth (which is basically nil), this LGTM.

[MatthieuDartiailh]

I was mostly worried about availability but this function is older than I though so no issue.