1 files changed, 106 insertions, 0 deletions
diff --git a/lib/gitlab/memory/reports_daemon.rb b/lib/gitlab/memory/reports_daemon.rb
new file mode 100644
index 00000000000..ed1da8baab5
--- /dev/null
+++ b/lib/gitlab/memory/reports_daemon.rb
@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Memory
+    class ReportsDaemon < Daemon
+      DEFAULT_SLEEP_S = 7200 # 2 hours
+      DEFAULT_SLEEP_MAX_DELTA_S = 600 # 0..10 minutes
+      DEFAULT_SLEEP_BETWEEN_REPORTS_S = 120 # 2 minutes
+
+      DEFAULT_REPORTS_PATH = '/tmp'
+
+      def initialize(**options)
+        super
+
+        @alive = true
+
+        @sleep_s =
+          ENV['GITLAB_DIAGNOSTIC_REPORTS_SLEEP_S']&.to_i || DEFAULT_SLEEP_S
+        @sleep_max_delta_s =
+          ENV['GITLAB_DIAGNOSTIC_REPORTS_SLEEP_MAX_DELTA_S']&.to_i || DEFAULT_SLEEP_MAX_DELTA_S
+        @sleep_between_reports_s =
+          ENV['GITLAB_DIAGNOSTIC_REPORTS_SLEEP_BETWEEN_REPORTS_S']&.to_i || DEFAULT_SLEEP_BETWEEN_REPORTS_S
+
+        @reports_path =
+          ENV["GITLAB_DIAGNOSTIC_REPORTS_PATH"] || DEFAULT_REPORTS_PATH
+
+        @reports = [Gitlab::Memory::Reports::JemallocStats.new(reports_path: reports_path)]
+
+        init_prometheus_metrics
+      end
+
+      attr_reader :sleep_s, :sleep_max_delta_s, :sleep_between_reports_s, :reports_path
+
+      def run_thread
+        while alive
+          sleep interval_with_jitter
+
+          reports.select(&:active?).each do |report|
+            start_monotonic_time = Gitlab::Metrics::System.monotonic_time
+            start_thread_cpu_time = Gitlab::Metrics::System.thread_cpu_time
+
+            file_path = report.run
+
+            cpu_s = Gitlab::Metrics::System.thread_cpu_duration(start_thread_cpu_time)
+            duration_s = Gitlab::Metrics::System.monotonic_time - start_monotonic_time
+
+            log_report(label: report_label(report), cpu_s: cpu_s, duration_s: duration_s, size: file_size(file_path))
+            @report_duration_counter.increment({ report: report_label(report) }, duration_s)
+
+            sleep sleep_between_reports_s
+          end
+        end
+      end
+
+      private
+
+      attr_reader :alive, :reports
+
+      # Returns the sleep interval with a random adjustment.
+      # The random adjustment is put in place to ensure continued availability.
+      def interval_with_jitter
+        sleep_s + rand(sleep_max_delta_s)
+      end
+
+      def log_report(label:, duration_s:, cpu_s:, size:)
+        Gitlab::AppLogger.info(
+          message: 'finished',
+          pid: $$,
+          worker_id: worker_id,
+          perf_report: label,
+          duration_s: duration_s.round(2),
+          cpu_s: cpu_s.round(2),
+          perf_report_size_bytes: size
+        )
+      end
+
+      def worker_id
+        ::Prometheus::PidProvider.worker_id
+      end
+
+      def report_label(report)
+        report.class.to_s.demodulize.underscore
+      end
+
+      def stop_working
+        @alive = false
+      end
+
+      def init_prometheus_metrics
+        default_labels = { pid: worker_id }
+
+        @report_duration_counter = Gitlab::Metrics.counter(
+          :gitlab_diag_report_duration_seconds_total,
+          'Total time elapsed for running diagnostic report',
+          default_labels
+        )
+      end
+
+      def file_size(file_path)
+        File.size(file_path.to_s)
+      rescue Errno::ENOENT
+        0
+      end
+    end
+  end
+end