Class: Sentry::Profiler

Inherits:
Object
  • Object
show all
Defined in:
lib/sentry/profiler.rb

Constant Summary collapse

VERSION = 
'1'
PLATFORM = 
'ruby'
DEFAULT_INTERVAL =

101 Hz in microseconds

1e6 / 101
MICRO_TO_NANO_SECONDS = 
1e3
MIN_SAMPLES_REQUIRED = 
2

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(configuration) ⇒ Profiler

Returns a new instance of Profiler.



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# File 'lib/sentry/profiler.rb', line 16

def initialize(configuration)
  @event_id = SecureRandom.uuid.delete('-')
  @started = false
  @sampled = nil

  @profiling_enabled = defined?(StackProf) && configuration.profiling_enabled?
  @profiles_sample_rate = configuration.profiles_sample_rate
  @project_root = configuration.project_root
  @app_dirs_pattern = configuration.app_dirs_pattern || Backtrace::APP_DIRS_PATTERN
  @in_app_pattern = Regexp.new("^(#{@project_root}/)?#{@app_dirs_pattern}")
end

Instance Attribute Details

#event_id ⇒ Object (readonly)

Returns the value of attribute event_id.



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# File 'lib/sentry/profiler.rb', line 14

def event_id
  @event_id
end

#sampled ⇒ Object (readonly)

Returns the value of attribute sampled.



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# File 'lib/sentry/profiler.rb', line 14

def sampled
  @sampled
end

#started ⇒ Object (readonly)

Returns the value of attribute started.



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# File 'lib/sentry/profiler.rb', line 14

def started
  @started
end

Instance Method Details

#set_initial_sample_decision(transaction_sampled) ⇒ void

This method returns an undefined value.

Sets initial sampling decision of the profile.



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# File 'lib/sentry/profiler.rb', line 49

def set_initial_sample_decision(transaction_sampled)
  unless @profiling_enabled
    @sampled = false
    return
  end

  unless transaction_sampled
    @sampled = false
    log('Discarding profile because transaction not sampled')
    return
  end

  case @profiles_sample_rate
  when 0.0
    @sampled = false
    log('Discarding profile because sample_rate is 0')
    return
  when 1.0
    @sampled = true
    return
  else
    @sampled = Random.rand < @profiles_sample_rate
  end

  log('Discarding profile due to sampling decision') unless @sampled
end

#start ⇒ Object 



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# File 'lib/sentry/profiler.rb', line 28

def start
  return unless @sampled

  @started = StackProf.start(interval: DEFAULT_INTERVAL,
                             mode: :wall,
                             raw: true,
                             aggregate: false)

  @started ? log('Started') : log('Not started since running elsewhere')
end

#stop ⇒ Object 



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# File 'lib/sentry/profiler.rb', line 39

def stop
  return unless @sampled
  return unless @started

  StackProf.stop
  log('Stopped')
end

#to_hash ⇒ Object 



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# File 'lib/sentry/profiler.rb', line 76

def to_hash
  unless @sampled
    record_lost_event(:sample_rate)
    return {}
  end

  return {} unless @started

  results = StackProf.results

  if !results || results.empty? || results[:samples] == 0 || !results[:raw]
    record_lost_event(:insufficient_data)
    return {}
  end

  frame_map = {}

  frames = results[:frames].to_enum.with_index.map do |frame, idx|
    frame_id, frame_data = frame

    # need to map over stackprof frame ids to ours
    frame_map[frame_id] = idx

    file_path = frame_data[:file]
    in_app = in_app?(file_path)
    filename = compute_filename(file_path, in_app)
    function, mod = split_module(frame_data[:name])

    frame_hash = {
      abs_path: file_path,
      function: function,
      filename: filename,
      in_app: in_app
    }

    frame_hash[:module] = mod if mod
    frame_hash[:lineno] = frame_data[:line] if frame_data[:line] && frame_data[:line] >= 0

    frame_hash
  end

  idx = 0
  stacks = []
  num_seen = []

  # extract stacks from raw
  # raw is a single array of [.., len_stack, *stack_frames(len_stack), num_stack_seen , ..]
  while (len = results[:raw][idx])
    idx += 1

    # our call graph is reversed
    stack = results[:raw].slice(idx, len).map { |id| frame_map[id] }.compact.reverse
    stacks << stack

    num_seen << results[:raw][idx + len]
    idx += len + 1

    log('Unknown frame in stack') if stack.size != len
  end

  idx = 0
  elapsed_since_start_ns = 0
  samples = []

  num_seen.each_with_index do |n, i|
    n.times do
      # stackprof deltas are in microseconds
      delta = results[:raw_timestamp_deltas][idx]
      elapsed_since_start_ns += (delta * MICRO_TO_NANO_SECONDS).to_i
      idx += 1

      # Not sure why but some deltas are very small like 0/1 values,
      # they pollute our flamegraph so just ignore them for now.
      # Open issue at https://github.com/tmm1/stackprof/issues/201
      next if delta < 10

      samples << {
        stack_id: i,
        # TODO-neel-profiler we need to patch rb_profile_frames and write our own C extension to enable threading info.
        # Till then, on multi-threaded servers like puma, we will get frames from other active threads when the one
        # we're profiling is idle/sleeping/waiting for IO etc.
        # https://bugs.ruby-lang.org/issues/10602
        thread_id: '0',
        elapsed_since_start_ns: elapsed_since_start_ns.to_s
      }
    end
  end

  log('Some samples thrown away') if samples.size != results[:samples]

  if samples.size <= MIN_SAMPLES_REQUIRED
    log('Not enough samples, discarding profiler')
    record_lost_event(:insufficient_data)
    return {}
  end

  profile = {
    frames: frames,
    stacks: stacks,
    samples: samples
  }

  {
    event_id: @event_id,
    platform: PLATFORM,
    version: VERSION,
    profile: profile
  }
end