Question

I know I can get the time take to evaluate a function can be printed out on the screen/stdout using the time function/macro.

The time macro returns the value of the evaluated function, which makes it great to use it inline. However I want to automatically measure the runtime under specific circumstances.

Is there a function which returns the elapsed time in some library to help with this benchmarking?

Answer 1

You might want to look into Hugo Duncan’s benchmarking library for Clojure — Criterium.

From the README:

Criterium measures the computation time of an expression. It is designed to address some of the pitfalls of benchmarking, and benchmarking on the JVM in particular.

This includes:

• statistical processing of multiple evaluations
• inclusion of a warm-up period, designed to allow the JIT compiler to optimise its code
• purging of gc before testing, to isolate timings from GC state prior to testing
• a final forced GC after testing to estimate impact of cleanup on the timing results