Class: NewRelic::Agent::PumaStatsSampler

Inherits:
Object
  • Object
show all
Defined in:
lib/new_relic/agent/puma_stats_sampler.rb

Overview

Samples Puma's clustered server statistics from the master process and records them as timeslice metrics under Ruby/Puma/*.

Only the master exposes cluster-wide stats (per-worker thread-pool backlog, running threads, pool_capacity, max_threads, requests_count), so sampling happens there.

This class restarts the harvest thread in the master via NewRelic::Agent.after_fork(force_reconnect: true) to deliver the sampled metrics. This starts an additional agent connection in the master.

Records only integer gauges/counters via NewRelic::Agent.record_metric (no request, query, or user data), so it is fully functional under High Security Mode.

Defined Under Namespace

Classes: UnrecognizedStatsError

Constant Summary collapse

METRIC_NAMESPACE = 
'Ruby/Puma'
INSTRUMENTATION_NAME = 
'Puma'
WORKER_STAT_KEYS =

Per-worker stat keys, summed across the cluster. requests_count is a cumulative counter (use rate() in NRQL); the rest are point-in-time gauges. pool_capacity is spare request capacity: idle threads plus unspawned threads still allowed up to max_threads.

%i[backlog running pool_capacity max_threads requests_count].freeze
RUNNER_INFO_KEYS =

Runner metadata reported by Puma::Runner#stats alongside (or, before the runner's Puma::Server exists, instead of) the per-worker keys.

%i[started_at versions].freeze
DEFAULT_SAMPLE_RATE = 
60
LOG_FAILURE_INTERVAL = 
10
LOG_FAILURE_TIME_FLOOR_SECONDS =

Caps how long a persistent failure can go unlogged: forces a re-log once ~5 min have elapsed, instead of waiting for the backed-off "every Nth" cadence (~55 min at the default sample rate).

300
BACKOFF_EXPONENT_CAP =

Caps backoff growth at 2**3 = 8 sample intervals.

3

Instance Method Summary collapse

Constructor Details

#initialize(stats_source) ⇒ PumaStatsSampler

Returns a new instance of PumaStatsSampler.



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# File 'lib/new_relic/agent/puma_stats_sampler.rb', line 50

def initialize(stats_source)
  @stats_source = stats_source
  @sample_rate = resolve_sample_rate
  @lock = Mutex.new
  @stop_signal = ConditionVariable.new
  @running = false
  @stopped = false
  @consecutive_failures = 0
  @last_failure_logged_at = nil
  @consecutive_report_failures = 0
  @last_report_failure_logged_at = nil
end

Instance Method Details

#start ⇒ Object

Runs the sampling loop on the background thread the instrumentation spawns in the master. Blocks until #stop is called from a Puma lifecycle event. Single-shot: the instrumentation builds one sampler per Puma boot, so #start is never re-entered on the same instance.



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# File 'lib/new_relic/agent/puma_stats_sampler.rb', line 67

def start
  return unless ensure_master_is_reporting

  NewRelic::Agent.record_instrumentation_invocation(INSTRUMENTATION_NAME)

  @lock.synchronize do
    return if @stopped

    @running = true
    begin
      while @running
        sample
        # Wait one interval (releases the lock); #stop wakes us early.
        # Re-check @running because the signal may have flipped it.
        @stop_signal.wait(@lock, next_wait_interval) if @running
      end
    ensure
      # Keep @running consistent if the loop aborts via an exception.
      @running = false
    end
  end
rescue => e
  # The instrumentation starts this loop on a bare +Thread.new+, so an
  # unhandled exception would silently kill the sampler thread. Log
  # StandardError; log and re-raise Exception so interrupts still propagate.
  ::NewRelic::Agent.logger.error('NewRelic Puma stats sampler thread exited with error', e)
rescue Exception => e
  ::NewRelic::Agent.logger.error('NewRelic Puma stats sampler thread exited with exception. Re-raising in case of interrupt.', e)
  raise
end

#stop ⇒ Object

Thread-safe: #stop runs on the Puma event thread, #start on the background thread.



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# File 'lib/new_relic/agent/puma_stats_sampler.rb', line 100

def stop
  @lock.synchronize do
    @running = false
    @stopped = true
    @stop_signal.signal
  end
end