BigW Consortium Gitlab

  1. 01 Aug, 2016 1 commit
  2. 28 Jul, 2016 1 commit
    • Reduce instrumentation overhead · 905f8d76
      Yorick Peterse authored
      This reduces the overhead of the method instrumentation code primarily
      by reducing the number of method calls. There are also some other small
      optimisations such as not casting timing values to Floats (there's no
      particular need for this), using Symbols for method call metric names,
      and reducing the number of Hash lookups for instrumented methods.
      
      The exact impact depends on the code being executed. For example, for a
      method that's only called once the difference won't be very noticeable.
      However, for methods that are called many times the difference can be
      more significant.
      
      For example, the loading time of a large commit
      (nrclark/dummy_project@81ebdea5df2fb42e59257cb3eaad671a5c53ca36)
      was reduced from around 19 seconds to around 15 seconds using these
      changes.
  3. 19 Jul, 2016 1 commit
  4. 20 Apr, 2016 1 commit
    • Fix setting of "action" for Grape transactions · a257d117
      Yorick Peterse authored
      Merely setting the "action" tag will only result in the transaction
      itself containing a value for this tag. To ensure other metrics also
      contain this tag we must set the action using Transaction#action=
      instead.
  5. 19 Apr, 2016 1 commit
    • Configuring of points per UDP packet · 229f3ce9
      Yorick Peterse authored
      This allows users to configure the number of points stored in a single
      UDP packet. This in turn can be used to reduce the number of UDP packets
      being sent at the cost of these packets being somewhat larger.
      
      The default setting is 1 point per packet so nothing changes for
      existing users.
  6. 13 Apr, 2016 1 commit
    • Added ability to add custom tags to transactions · 3240ecfb
      Yorick Peterse authored
      One use case for this is manually setting the "action" tag for Grape API
      calls. Due to Grape running blocks there are no human readable method
      names that can be used for the "action" tag, thus we have to set these
      manually on a case by case basis.
  7. 11 Apr, 2016 3 commits
  8. 06 Apr, 2016 1 commit
    • Measure Ruby blocks using Gitlab::Metrics · 1af6cf28
      Yorick Peterse authored
      This allows measuring of timings of arbitrary Ruby blocks, this allows
      for more fine grained performance monitoring. Custom values and tags can
      also be attached to a block.
  9. 13 Jan, 2016 1 commit
  10. 12 Jan, 2016 1 commit
    • Stop tracking call stacks for instrumented views · 355c341f
      Yorick Peterse authored
      Where a vew is called from doesn't matter as much. We already know what
      action they belong to and this is more than enough information. By
      removing the file/line number from the list of tags we should also be
      able to reduce the number of series stored in InfluxDB.
  11. 06 Jan, 2016 1 commit
  12. 31 Dec, 2015 2 commits
  13. 29 Dec, 2015 2 commits
    • Use Gitlab::CurrentSettings for InfluxDB · 701e5de9
      Yorick Peterse authored
      This ensures we can still start up even when not connecting to a
      database.
    • Write to InfluxDB directly via UDP · 620e7bb3
      Yorick Peterse authored
      This removes the need for Sidekiq and any overhead/problems introduced
      by TCP. There are a few things to take into account:
      
      1. When writing data to InfluxDB you may still get an error if the
         server becomes unavailable during the write. Because of this we're
         catching all exceptions and just ignore them (for now).
      2. Writing via UDP apparently requires the timestamp to be in
         nanoseconds. Without this data either isn't written properly.
      3. Due to the restrictions on UDP buffer sizes we're writing metrics one
         by one, instead of writing all of them at once.
  14. 28 Dec, 2015 3 commits
  15. 17 Dec, 2015 4 commits
    • Track object counts using the "allocations" Gem · f181f05e
      Yorick Peterse authored
      This allows us to track the counts of actual classes instead of "T_XXX"
      nodes. This is only enabled on CRuby as it uses CRuby specific APIs.
    • Only track method calls above a certain threshold · a41287d8
      Yorick Peterse authored
      This ensures we don't end up wasting resources by tracking method calls
      that only take a few microseconds. By default the threshold is 10
      milliseconds but this can be changed using the gitlab.yml configuration
      file.
    • Improved last_relative_application_frame timings · 60a6a240
      Yorick Peterse authored
      The previous setup wasn't exactly fast, resulting in instrumented method
      calls taking about 600 times longer than non instrumented calls
      (including any ActiveSupport code involved). With this commit this
      slowdown has been reduced to around 185 times.
    • Storing of application metrics in InfluxDB · 141e946c
      Yorick Peterse authored
      This adds the ability to write application metrics (e.g. SQL timings) to
      InfluxDB. These metrics can in turn be visualized using Grafana, or
      really anything else that can read from InfluxDB. These metrics can be
      used to track application performance over time, between different Ruby
      versions, different GitLab versions, etc.
      
      == Transaction Metrics
      
      Currently the following is tracked on a per transaction basis (a
      transaction is a Rails request or a single Sidekiq job):
      
      * Timings per query along with the raw (obfuscated) SQL and information
        about what file the query originated from.
      * Timings per view along with the path of the view and information about
        what file triggered the rendering process.
      * The duration of a request itself along with the controller/worker
        class and method name.
      * The duration of any instrumented method calls (more below).
      
      == Sampled Metrics
      
      Certain metrics can't be directly associated with a transaction. For
      example, a process' total memory usage is unrelated to any running
      transactions. While a transaction can result in the memory usage going
      up there's no accurate way to determine what transaction is to blame,
      this becomes especially problematic in multi-threaded environments.
      
      To solve this problem there's a separate thread that takes samples at a
      fixed interval. This thread (using the class Gitlab::Metrics::Sampler)
      currently tracks the following:
      
      * The process' total memory usage.
      * The number of file descriptors opened by the process.
      * The amount of Ruby objects (using ObjectSpace.count_objects).
      * GC statistics such as timings, heap slots, etc.
      
      The default/current interval is 15 seconds, any smaller interval might
      put too much pressure on InfluxDB (especially when running dozens of
      processes).
      
      == Method Instrumentation
      
      While currently not yet used methods can be instrumented to track how
      long they take to run. Unlike the likes of New Relic this doesn't
      require modifying the source code (e.g. including modules), it all
      happens from the outside. For example, to track `User.by_login` we'd add
      the following code somewhere in an initializer:
      
          Gitlab::Metrics::Instrumentation.
            instrument_method(User, :by_login)
      
      to instead instrument an instance method:
      
          Gitlab::Metrics::Instrumentation.
            instrument_instance_method(User, :save)
      
      Instrumentation for either all public model methods or a few crucial
      ones will be added in the near future, I simply haven't gotten to doing
      so just yet.
      
      == Configuration
      
      By default metrics are disabled. This means users don't have to bother
      setting anything up if they don't want to. Metrics can be enabled by
      editing one's gitlab.yml configuration file (see
      config/gitlab.yml.example for example settings).
      
      == Writing Data To InfluxDB
      
      Because InfluxDB is still a fairly young product I expect the worse.
      Data loss, unexpected reboots, the database not responding, you name it.
      Because of this data is _not_ written to InfluxDB directly, instead it's
      queued and processed by Sidekiq. This ensures that users won't notice
      anything when InfluxDB is giving trouble.
      
      The metrics worker can be started in a standalone manner as following:
      
          bundle exec sidekiq -q metrics
      
      The corresponding class is called MetricsWorker.