diff options
Diffstat (limited to 'doc/development/profiling.md')
| -rw-r--r-- | doc/development/profiling.md | 63 |
1 files changed, 12 insertions, 51 deletions
diff --git a/doc/development/profiling.md b/doc/development/profiling.md index a3142b06e12..3eb2c7c9144 100644 --- a/doc/development/profiling.md +++ b/doc/development/profiling.md @@ -1,7 +1,7 @@ --- stage: none group: unassigned -info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments +info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments --- # Profiling @@ -20,6 +20,9 @@ The first argument to the profiler is either a full URL (including the instance hostname) or an absolute path, including the leading slash. +By default the report dump will be stored in a temporary file, which can be +interacted with using the [stackprof API](#reading-a-gitlabprofiler-report). + When using the script, command-line documentation is available by passing no arguments. @@ -31,10 +34,11 @@ For example: ```ruby Gitlab::Profiler.profile('/my-user') -# Returns a RubyProf::Profile for the regular operation of this request +# Returns the location of the temp file where the report dump is stored class UsersController; def show; sleep 100; end; end Gitlab::Profiler.profile('/my-user') -# Returns a RubyProf::Profile where 100 seconds is spent in UsersController#show +# Returns the location of the temp file where the report dump is stored +# where 100 seconds is spent in UsersController#show ``` For routes that require authorization you must provide a user to @@ -52,57 +56,14 @@ documented with the method source. Gitlab::Profiler.profile('/gitlab-org/gitlab-test', user: User.first, logger: Logger.new($stdout)) ``` -There is also a RubyProf printer available: -`Gitlab::Profiler::TotalTimeFlatPrinter`. This acts like -`RubyProf::FlatPrinter`, but its `min_percent` option works on the method's -total time, not its self time. (This is because we often spend most of our time -in library code, but this comes from calls in our application.) It also offers a -`max_percent` option to help filter out outer calls that aren't useful (like -`ActionDispatch::Integration::Session#process`). - -There is a convenience method for using this, -`Gitlab::Profiler.print_by_total_time`: - -```ruby -result = Gitlab::Profiler.profile('/my-user') -Gitlab::Profiler.print_by_total_time(result, max_percent: 60, min_percent: 2) -# Measure Mode: wall_time -# Thread ID: 70005223698240 -# Fiber ID: 70004894952580 -# Total: 1.768912 -# Sort by: total_time -# -# %self total self wait child calls name -# 0.00 1.017 0.000 0.000 1.017 14 *ActionView::Helpers::RenderingHelper#render -# 0.00 1.017 0.000 0.000 1.017 14 *ActionView::Renderer#render_partial -# 0.00 1.017 0.000 0.000 1.017 14 *ActionView::PartialRenderer#render -# 0.00 1.007 0.000 0.000 1.007 14 *ActionView::PartialRenderer#render_partial -# 0.00 0.930 0.000 0.000 0.930 14 Hamlit::TemplateHandler#call -# 0.00 0.928 0.000 0.000 0.928 14 Temple::Engine#call -# 0.02 0.865 0.000 0.000 0.864 638 *Enumerable#inject -``` - -To print the profile in HTML format, use the following example: - -```ruby -result = Gitlab::Profiler.profile('/my-user') - -printer = RubyProf::CallStackPrinter.new(result) -printer.print(File.open('/tmp/profile.html', 'w')) -``` - -### Stackprof support - -By default, `Gitlab::Profiler.profile` uses a tracing profiler called [`ruby-prof`](https://ruby-prof.github.io/). However, sampling profilers -[run faster and use less memory](https://jvns.ca/blog/2017/12/17/how-do-ruby---python-profilers-work-/), so they might be preferred. - -You can switch to [Stackprof](https://github.com/tmm1/stackprof) (a sampling profiler) to generate a profile by passing `sampling_mode: true`. Pass in a `profiler_options` hash to configure the output file (`out`) of the sampling data. For example: ```ruby -Gitlab::Profiler.profile('/gitlab-org/gitlab-test', user: User.first, sampling_mode: true, profiler_options: { out: 'tmp/profile.dump' }) +Gitlab::Profiler.profile('/gitlab-org/gitlab-test', user: User.first, profiler_options: { out: 'tmp/profile.dump' }) ``` +## Reading a GitLab::Profiler report + You can get a summary of where time was spent by running Stackprof against the sampling data. For example: ```shell @@ -244,7 +205,7 @@ Example output: ``` NOTE: -This endpoint is only available for Rails web workers. Sidekiq workers can not be inspected this way. +This endpoint is only available for Rails web workers. Sidekiq workers cannot be inspected this way. ## Settings that impact performance @@ -286,7 +247,7 @@ The following table lists these variables along with their default values. ([Source](https://github.com/ruby/ruby/blob/45b29754cfba8435bc4980a87cd0d32c648f8a2e/gc.c#L254-L308)) -GitLab may decide to change these settings in order to speed up application performance, lower memory requirements, or both. +GitLab may decide to change these settings to speed up application performance, lower memory requirements, or both. You can see how each of these settings affect GC performance, memory use and application start-up time for an idle instance of GitLab by running the `scripts/perf/gc/collect_gc_stats.rb` script. It will output GC stats and general timing data to standard |