Timing code execution

Questions / Help
1

Hello,

I just ran the following code to time how long a part of a function takes to execute:

time1 = NaiveDateTime.utc_now

...some code or function call...

time2 = NaiveDateTime.utc_now

time_total = NaiveDateTime.diff(time2, time1, :microsecond)

time_total came back remarkably low (two-digit microseconds). Quite plausible (and fascinating!), but might I be missing something with this logic, particularly if a function call is between time1 and time2?

Thank you.

2

If you want to do a micro benchmark (measure how long a function takes), doing one run of the function is not enough.
You can take a look at https://github.com/bencheeorg/benchee to run microbenchmarks.

1 Like
3

Thank @tcoopman, great advice, looking into Benchee now.

4

…and now also doing my own “quick stats” by just running the code multiple times and getting a rough sense for the distribution of time outcomes as well as some average :slight_smile:

5

Even though there are indeed benchmarking frameworks available, there is also :timer.tc/1,2,3 in Erlang.

For one time measurements, eg. for some progress report or sending to a metrics service, it’s usually sufficient.

3 Likes
6

Thank you, @NobbZ!