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+# 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.