Class: DeadBro::MemoryLeakDetector

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

Overview

Process-wide memory leak detector. Previously stored samples in ‘Thread.current`, which meant each Puma worker thread saw only the handful of requests it served — far too few samples, and reset whenever a thread was recycled. History is now shared across all threads in the process behind a mutex, with a hard cap on the number of retained samples.

Constant Summary collapse

LEAK_DETECTION_WINDOW =

seconds (5 minutes)

300
MEMORY_GROWTH_THRESHOLD =

MB growth over the window

50
MIN_SAMPLES_FOR_LEAK_DETECTION = 
10
MAX_SAMPLES =

hard cap so a long-running process can’t grow unbounded

500
MAX_LEAK_ALERTS = 
10

Class Method Summary collapse

Class Method Details

.calculate_memory_efficiency(samples) ⇒ Object 



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# File 'lib/dead_bro/memory_leak_detector.rb', line 141

def calculate_memory_efficiency(samples)
  return {} if samples.length < 2

  memory_per_object = samples.map do |sample|
    (sample[:object_count] > 0) ? sample[:memory_usage] / sample[:object_count] : 0
  end

  gc_efficiency = []
  (1...samples.length).each do |i|
    gc_delta = samples[i][:gc_count] - samples[i - 1][:gc_count]
    memory_delta = samples[i][:memory_usage] - samples[i - 1][:memory_usage]

    if gc_delta > 0 && memory_delta < 0
      gc_efficiency << (-memory_delta / gc_delta).round(2)
    end
  end

  {
    average_memory_per_object_kb: (memory_per_object.sum / memory_per_object.length).round(2),
    gc_efficiency_mb_per_cycle: gc_efficiency.any? ? (gc_efficiency.sum / gc_efficiency.length).round(2) : 0,
    memory_volatility: calculate_standard_deviation(samples.map { |s| s[:memory_usage] })
  }
end

.calculate_memory_trend(memory_values, timestamps) ⇒ Object 



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# File 'lib/dead_bro/memory_leak_detector.rb', line 98

def calculate_memory_trend(memory_values, timestamps)
  return {slope: 0, r_squared: 0} if memory_values.length < 2

  n = memory_values.length
  sum_x = timestamps.sum
  sum_y = memory_values.sum
  sum_xy = timestamps.zip(memory_values).sum { |x, y| x * y }
  sum_x2 = timestamps.sum { |x| x * x }

  denominator = (n * sum_x2 - sum_x * sum_x)
  return {slope: 0, r_squared: 0} if denominator.zero?

  slope = (n * sum_xy - sum_x * sum_y).to_f / denominator
  intercept = (sum_y - slope * sum_x).to_f / n

  y_mean = sum_y.to_f / n
  ss_tot = memory_values.sum { |y| (y - y_mean)**2 }
  ss_res = memory_values.zip(timestamps).sum { |y, x| (y - (slope * x + intercept))**2 }
  r_squared = (ss_tot > 0) ? 1 - (ss_res / ss_tot) : 0

  {slope: slope, intercept: intercept, r_squared: r_squared}
end

.calculate_standard_deviation(values) ⇒ Object 



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# File 'lib/dead_bro/memory_leak_detector.rb', line 133

def calculate_standard_deviation(values)
  return 0 if values.length < 2

  mean = values.sum.to_f / values.length
  variance = values.sum { |v| (v - mean)**2 } / (values.length - 1)
  Math.sqrt(variance).round(2)
end

.calculate_stats(values) ⇒ Object 



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# File 'lib/dead_bro/memory_leak_detector.rb', line 121

def calculate_stats(values)
  return {} if values.empty?

  {
    min: values.min,
    max: values.max,
    mean: (values.sum.to_f / values.length).round(2),
    median: values.sort[values.length / 2],
    std_dev: calculate_standard_deviation(values)
  }
end

.clear_history ⇒ Object 



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# File 'lib/dead_bro/memory_leak_detector.rb', line 82

def clear_history
  @mutex.synchronize do
    @history = {
      samples: [],
      last_cleanup: Time.now.utc.to_i,
      leak_alerts: []
    }
  end
end

.get_memory_analysis ⇒ Object 



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# File 'lib/dead_bro/memory_leak_detector.rb', line 47

def get_memory_analysis
  samples_snapshot, leak_alerts_snapshot = @mutex.synchronize do
    [@history[:samples].dup, @history[:leak_alerts].dup]
  end

  if samples_snapshot.length < 5
    return {status: "insufficient_data", sample_count: samples_snapshot.length}
  end

  memory_values = samples_snapshot.map { |s| s[:memory_usage] }
  gc_counts = samples_snapshot.map { |s| s[:gc_count] }
  object_counts = samples_snapshot.map { |s| s[:object_count] }

  memory_stats = calculate_stats(memory_values)
  gc_stats = calculate_stats(gc_counts)
  object_stats = calculate_stats(object_counts)
  memory_trend = calculate_memory_trend(memory_values, samples_snapshot.map { |s| s[:timestamp] })

  recent_samples = samples_snapshot.last(10)
  recent_controllers = recent_samples.map { |s| "#{s[:controller]}##{s[:action]}" }.tally

  {
    status: "analyzed",
    sample_count: samples_snapshot.length,
    time_window_seconds: samples_snapshot.last[:timestamp] - samples_snapshot.first[:timestamp],
    memory_stats: memory_stats,
    gc_stats: gc_stats,
    object_stats: object_stats,
    memory_trend: memory_trend,
    recent_controllers: recent_controllers,
    leak_alerts: leak_alerts_snapshot.last(5),
    memory_efficiency: calculate_memory_efficiency(samples_snapshot)
  }
end

.initialize_history ⇒ Object

Kept for backwards compatibility — history is now initialized at class-load time, so Railtie callers don’t need to do anything.



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# File 'lib/dead_bro/memory_leak_detector.rb', line 94

def initialize_history
  # no-op
end

.record_memory_sample(sample_data) ⇒ Object 



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# File 'lib/dead_bro/memory_leak_detector.rb', line 24

def record_memory_sample(sample_data)
  sample = {
    timestamp: Time.now.utc.to_i,
    memory_usage: sample_data[:memory_usage] || 0,
    gc_count: sample_data[:gc_count] || 0,
    heap_pages: sample_data[:heap_pages] || 0,
    object_count: sample_data[:object_count] || 0,
    request_id: sample_data[:request_id],
    controller: sample_data[:controller],
    action: sample_data[:action]
  }

  samples_snapshot = @mutex.synchronize do
    @history[:samples] << sample
    cleanup_old_samples_unlocked
    @history[:samples].dup
  end

  check_for_memory_leaks(samples_snapshot)

  nil
end