Profiling was introduced in RuboCop 1.45.

RuboCop comes with the ability to profile itself while running. It has 2 CLI options:

  • the --profile option will use a stackprof gem(you need to have it in Gemfile) to profile wall time and print a report at the tmp/rubocop-stackprof.dump location of the project. See the gem’s documentation on how to interpret the results

  • the --memory option will additionally profile memory usage using memory_profiler gem(you need to have it in Gemfile) and print a report at the tmp/rubocop-memory_profiler.txt location of the project

Profiling memory can be very costly and time consuming when run on a large codebase. In this case, it is recommended to use it over a limited set of files (app/ directory, for example) or use a limited set of cops (with --only, for example).

Reporting Back

If you found a performance problem in RuboCop, you are encouraged to report back via an issue or a pull request. See Contributing Guide for more details.