GitLab Documentation

Profiling

To make it easier to track down performance problems GitLab comes with a set of profiling tools, some of these are available by default while others need to be explicitly enabled.

Sherlock

Sherlock is a custom profiling tool built into GitLab. Sherlock is only available when running GitLab in development mode and when setting the environment variable ENABLE_SHERLOCK to a non empty value. For example:

ENABLE_SHERLOCK=1 bundle exec rails s

Recorded transactions can be found by navigating to /sherlock/transactions.

Bullet

Bullet is a Gem that can be used to track down N+1 query problems. Because Bullet adds quite a bit of logging noise it's disabled by default. To enable Bullet, set the environment variable ENABLE_BULLET to a non-empty value before starting GitLab. For example:

ENABLE_BULLET=true bundle exec rails s

Bullet will log query problems to both the Rails log as well as the Chrome console.

As a follow up to finding N+1 queries with Bullet, consider writing a QueryRecoder test to prevent a regression.