Class: DeadBro::MemoryTrackingSubscriber

Inherits:
Object
  • Object
show all
Defined in:
lib/dead_bro/memory_tracking_subscriber.rb

Constant Summary collapse

PROCESS_ACTION_EVENT =

Allocation counts come from the process_action event (Rails instruments allocations there via ActiveSupport::Notifications). The old “object_allocations.active_support” constant was never emitted by Rails, so that subscription was dead code — removed.

"process_action.action_controller"
THREAD_LOCAL_KEY = 
:dead_bro_memory_events
LARGE_OBJECT_THRESHOLD =

Consider objects larger than this many bytes as “large”

1_000_000
MAX_ALLOCATIONS_PER_REQUEST =

Performance optimization settings

1000
LARGE_OBJECT_SAMPLE_RATE =

Limit allocations tracked per request

0.01
MAX_LARGE_OBJECTS =

Sample 1% of live objects to estimate large ones

50

Class Method Summary collapse

Class Method Details

.analyze_large_objects(large_objects) ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 241

def self.analyze_large_objects(large_objects)
  return {} if large_objects.empty?

  {
    count: large_objects.count,
    total_size_mb: large_objects.sum { |obj| obj[:size_mb] }.round(2),
    largest_object_mb: large_objects.max_by { |obj| obj[:size_mb] }[:size_mb],
    by_class: large_objects.group_by { |obj| obj[:class_name] }
      .transform_values(&:count)
  }
end

.analyze_memory_performance(memory_events) ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 154

def self.analyze_memory_performance(memory_events)
  return {} if memory_events.empty?

  allocations = memory_events[:allocations] || []
  large_objects = memory_events[:large_objects] || []
  snapshots = memory_events[:memory_snapshots] || []
  request_allocations = memory_events[:request_allocations]

  # Calculate memory growth
  memory_growth = 0
  if memory_events[:memory_before] && memory_events[:memory_after]
    memory_growth = memory_events[:memory_after] - memory_events[:memory_before]
  end

  # Calculate allocation totals
  total_allocations = allocations.sum { |a| a[:count] }
  total_allocated_size = allocations.sum { |a| a[:size] }
  if request_allocations
    total_allocated_size = request_allocations[:allocated_bytes].to_i if total_allocated_size.zero?
  end
  gc_allocations = nil
  if memory_events[:gc_before] && memory_events[:gc_after]
    gc_allocations = (memory_events[:gc_after][:total_allocated_objects] || 0) -
      (memory_events[:gc_before][:total_allocated_objects] || 0)
  end
  if gc_allocations.to_i > 0
    total_allocations = gc_allocations
  elsif total_allocations.zero? && request_allocations
    total_allocations = request_allocations[:allocations].to_i
  end

  # Group allocations by class
  allocations_by_class = allocations.group_by { |a| a[:class_name] }
    .transform_values { |allocs|
      {
        count: allocs.sum { |a| a[:count] },
        size: allocs.sum { |a| a[:size] }
      }
  }

  # Find top allocating classes
  top_allocating_classes = allocations_by_class.sort_by { |_, data| -data[:size] }.first(10)

  # Analyze large objects
  large_object_analysis = analyze_large_objects(large_objects)

  # Analyze memory snapshots for trends
  memory_trends = analyze_memory_trends(snapshots)

  # Calculate GC efficiency
  gc_efficiency = calculate_gc_efficiency(memory_events[:gc_before], memory_events[:gc_after])

  # Analyze object type deltas (by Ruby object type, not class)
  object_type_deltas = {}
  if memory_events[:object_counts_before].is_a?(Hash) && memory_events[:object_counts_after].is_a?(Hash)
    before = memory_events[:object_counts_before]
    after = memory_events[:object_counts_after]
    keys = (before.keys + after.keys).uniq
    keys.each do |k|
      object_type_deltas[k] = (after[k] || 0) - (before[k] || 0)
    end
  end

  {
    memory_growth_mb: memory_growth.round(2),
    total_allocations: total_allocations,
    total_allocated_size: total_allocated_size,
    total_allocated_size_mb: (total_allocated_size / 1_000_000.0).round(2),
    allocations_per_second: (memory_events[:duration_seconds] > 0) ?
      (total_allocations.to_f / memory_events[:duration_seconds]).round(2) : 0,
    top_allocating_classes: top_allocating_classes.map { |class_name, data|
      {
        class: class_name,
        name: class_name,
        count: data[:count],
        size: data[:size],
        size_mb: (data[:size] / 1_000_000.0).round(2)
      }
    },
    large_objects: large_object_analysis,
    memory_trends: memory_trends,
    gc_efficiency: gc_efficiency,
    memory_snapshots_count: snapshots.count,
    object_type_deltas: top_object_type_deltas(object_type_deltas, limit: 10)
  }
end

.analyze_memory_trends(snapshots) ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 306

def self.analyze_memory_trends(snapshots)
  return {} if snapshots.length < 2

  # Calculate memory growth rate between snapshots
  memory_values = snapshots.map { |s| s[:memory_usage] }
  memory_growth_rates = []

  (1...memory_values.length).each do |i|
    growth = memory_values[i] - memory_values[i - 1]
    time_diff = snapshots[i][:timestamp] - snapshots[i - 1][:timestamp]
    rate = (time_diff > 0) ? growth / time_diff : 0
    memory_growth_rates << rate
  end

  {
    average_growth_rate_mb_per_second: memory_growth_rates.sum / memory_growth_rates.length,
    max_growth_rate_mb_per_second: memory_growth_rates.max,
    memory_volatility: memory_growth_rates.map(&:abs).sum / memory_growth_rates.length,
    peak_memory_mb: memory_values.max,
    min_memory_mb: memory_values.min
  }
end

.calculate_gc_efficiency(gc_before, gc_after) ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 329

def self.calculate_gc_efficiency(gc_before, gc_after)
  return {} unless gc_before && gc_after

  {
    gc_count_increase: (gc_after[:count] || 0) - (gc_before[:count] || 0),
    heap_pages_increase: (gc_after[:heap_allocated_pages] || 0) - (gc_before[:heap_allocated_pages] || 0),
    objects_allocated: (gc_after[:total_allocated_objects] || 0) - (gc_before[:total_allocated_objects] || 0),
    gc_frequency: (gc_after[:count] && gc_before[:count]) ?
      (gc_after[:count] - gc_before[:count]).to_f / [gc_after[:count], 1].max : 0
  }
end

.count_objects_snapshot ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 296

def self.count_objects_snapshot
  if defined?(ObjectSpace) && ObjectSpace.respond_to?(:count_objects)
    ObjectSpace.count_objects.dup
  else
    {}
  end
rescue
  {}
end

.current_events ⇒ Object

Current frame (top of stack) for nested job tracking; nil if none.



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 52

def self.current_events
  stack = Thread.current[THREAD_LOCAL_KEY]
  return nil unless stack.is_a?(Array) && stack.any?
  stack.last
end

.gc_stats ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 349

def self.gc_stats
  if defined?(GC) && GC.respond_to?(:stat)
    stats = GC.stat
    {
      count: stats[:count] || 0,
      heap_allocated_pages: stats[:heap_allocated_pages] || 0,
      heap_sorted_pages: stats[:heap_sorted_pages] || 0,
      total_allocated_objects: stats[:total_allocated_objects] || 0,
      heap_live_slots: stats[:heap_live_slots] || 0,
      heap_eden_pages: stats[:heap_eden_pages] || 0,
      heap_tomb_pages: stats[:heap_tomb_pages] || 0
    }
  else
    {}
  end
rescue
  {}
end

.heap_pages ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 378

def self.heap_pages
  if defined?(GC) && GC.respond_to?(:stat)
    GC.stat[:heap_allocated_pages] || 0
  else
    0
  end
rescue
  0
end

.memory_usage_mb ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 341

def self.memory_usage_mb
  # MemoryHelpers.rss_mb reads /proc/self/status on Linux and caches for
  # ~1 second across threads, so this is safe to call per-request.
  DeadBro::MemoryHelpers.rss_mb
rescue
  0
end

.object_count ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 368

def self.object_count
  if defined?(GC) && GC.respond_to?(:stat)
    GC.stat[:heap_live_slots] || 0
  else
    0
  end
rescue
  0
end

.object_space_available? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 258

def self.object_space_available?
  defined?(ObjectSpace) && ObjectSpace.respond_to?(:each_object) && ObjectSpace.respond_to?(:memsize_of)
end

.record_request_allocations(allocations:, allocated_bytes:) ⇒ Object

Record request-level allocation counters from Rails instrumentation.



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 97

def self.record_request_allocations(allocations:, allocated_bytes:)
  events = current_events
  return unless events

  events[:request_allocations] = {
    allocations: allocations,
    allocated_bytes: allocated_bytes
  }
end

.sample_large_objects ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 262

def self.sample_large_objects
  results = []
  return results unless object_space_available?

  begin
    # Sample across common heap object types
    ObjectSpace.each_object do |obj|
      # Randomly sample to control overhead
      next unless rand < LARGE_OBJECT_SAMPLE_RATE

      size = begin
        ObjectSpace.memsize_of(obj)
      rescue
        0
      end
      next unless size && size > LARGE_OBJECT_THRESHOLD

      klass = begin
        (obj.respond_to?(:class) && obj.class) ? obj.class.name : "Unknown"
      rescue
        "Unknown"
      end
      results << {class_name: klass, size: size, size_mb: (size / 1_000_000.0).round(2)}

      break if results.length >= MAX_LARGE_OBJECTS
    end
  rescue
    # Best-effort only
  end

  # Sort largest first and keep top N
  results.sort_by { |h| -h[:size] }.first(MAX_LARGE_OBJECTS)
end

.snapshot_at(label) ⇒ Object

Helper method to take memory snapshots at specific points



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 389

def self.snapshot_at(label)
  take_memory_snapshot(label)
end

.start_request_tracking ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 58

def self.start_request_tracking
  # Only track if memory tracking is enabled
  return unless DeadBro.configuration.memory_tracking_enabled

  frame = {
    allocations: [],
    memory_snapshots: [],
    large_objects: [],
    request_allocations: nil,
    gc_before: gc_stats,
    memory_before: memory_usage_mb,
    start_time: Time.now.to_f,
    object_counts_before: count_objects_snapshot
  }
  (Thread.current[THREAD_LOCAL_KEY] ||= []) << frame
end

.stop_request_tracking ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 75

def self.stop_request_tracking
  stack = Thread.current[THREAD_LOCAL_KEY]
  events = (stack.is_a?(Array) && stack.any?) ? stack.pop : nil
  Thread.current[THREAD_LOCAL_KEY] = nil if stack.nil? || stack.empty?

  if events
    events[:gc_after] = gc_stats
    events[:memory_after] = memory_usage_mb
    events[:end_time] = Time.now.to_f
    events[:duration_seconds] = events[:end_time] - events[:start_time]
    events[:object_counts_after] = count_objects_snapshot

    # Fallback large object detection via ObjectSpace sampling
    if (events[:large_objects].nil? || events[:large_objects].empty?) && object_space_available?
      events[:large_objects] = sample_large_objects
    end
  end

  events || {}
end

.subscribe!(client: Client.new) ⇒ Object

Cap number of large objects captured per request



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 22

def self.subscribe!(client: Client.new)
  # Only enable allocation tracking if explicitly enabled (expensive!)
  return unless DeadBro.configuration.allocation_tracking_enabled
  if defined?(ActiveSupport::Notifications) && ActiveSupport::Notifications.notifier.respond_to?(:subscribe)
    begin
      # Subscribe to process_action to capture request-level allocation counters
      ActiveSupport::Notifications.subscribe(PROCESS_ACTION_EVENT) do |*args|
        event = if args.length == 1 && args.first.is_a?(ActiveSupport::Notifications::Event)
          args.first
        else
          ActiveSupport::Notifications::Event.new(*args)
        end
        allocations = event.respond_to?(:allocations) ? event.allocations : event.payload[:allocations]
        allocated_bytes = event.respond_to?(:allocated_bytes) ? event.allocated_bytes : event.payload[:allocated_bytes]
        next unless allocations || allocated_bytes

        record_request_allocations(
          allocations: allocations,
          allocated_bytes: allocated_bytes
        )
      end
    rescue
      # Allocation tracking might not be available in all Ruby versions
    end
  end
rescue
  # Never raise from instrumentation install
end

.take_memory_snapshot(label = nil) ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 138

def self.take_memory_snapshot(label = nil)
  events = current_events
  return unless events

  snapshot = {
    label: label || "snapshot_#{Time.now.to_i}",
    memory_usage: memory_usage_mb,
    gc_stats: gc_stats,
    timestamp: Time.now.utc.to_i,
    object_count: object_count,
    heap_pages: heap_pages
  }

  events[:memory_snapshots] << snapshot
end

.top_object_type_deltas(deltas, limit: 10) ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 253

def self.top_object_type_deltas(deltas, limit: 10)
  return {} unless deltas.is_a?(Hash)
  deltas.sort_by { |_, v| -v.abs }.first(limit).to_h
end

.track_allocation(data, started, finished) ⇒ Object 



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# File 'lib/dead_bro/memory_tracking_subscriber.rb', line 107

def self.track_allocation(data, started, finished)
  events = current_events
  return unless events

  # Only track if we have meaningful allocation data
  return unless data.is_a?(Hash) && data[:count] && data[:size]

  # Limit allocations per request to prevent memory bloat
  allocations = events[:allocations]
  return if allocations.length >= MAX_ALLOCATIONS_PER_REQUEST

  # Simplified allocation tracking (avoid expensive operations)
  allocation = {
    class_name: data[:class_name] || "Unknown",
    count: data[:count],
    size: data[:size]
    # Removed expensive fields: duration_ms, timestamp, memory_usage
  }

  # Track large object allocations (these are rare and important)
  if data[:size] > LARGE_OBJECT_THRESHOLD
    large_object = allocation.merge(
      large_object: true,
      size_mb: (data[:size] / 1_000_000.0).round(2)
    )
    events[:large_objects] << large_object
  end

  events[:allocations] << allocation
end