Use Process.clock_gettime to measure track execution time

[mrzasa]

Using any variation of Time.now is not a reliable way of measuring elapsed time. It may be affected by jumps in local clock. Instead we can use a more reliable Process.clock_gettime(Process::CLOCK_MONOTINIC).

I've removed a Timecop dependency from the production code, but left it in the tests to check that a new solution works correctly with Timecop.

For detailed explaination, please read this excellent blogpost: https://blog.dnsimple.com/2018/03/elapsed-time-with-ruby-the-right-way/

[ArturT]

@mrzasa Interesting article. Thank you for sharing.

So this solution should work fine when someone manipulates time with Timecop or uses Rails travel_to method, right?

I added this PR to my TODO list to take care of it.

[mrzasa]

I tested that it works correctly Timecop. travel_to stubs Date, Time and Datetime, so Process.clock_gettime shouldn't be affected.

[ArturT]

Thank you @mrzasa

[ArturT]

@mrzasa I've released a new version of knapsack gem 1.20.0

I also released a new version of knapsack_pro gem KnapsackPro/knapsack_pro-ruby#132

Here you can learn more about how Queue Mode in knapsack_pro gem can help run tests faster https://docs.knapsackpro.com/2020/how-to-speed-up-ruby-and-javascript-tests-with-ci-parallelisation

or you can check the latest feature to auto split slow RSpec test files by test examples:
https://knapsackpro.com/faq/question/how-to-split-slow-rspec-test-files-by-test-examples-by-individual-it