Add back ruby_memory_bytes metric, limit duplication, clean up

This adds back ruby_memory_bytes for backwards compatibility, limits
code duplication, cleans up unused methods, and limits the unicorn
worker sampling scope.

doc/administration/monitoring/prometheus/gitlab_metrics.md

@@ -58,10 +58,11 @@ Some basic Ruby runtime metrics are available:
 | ruby_gc_duration_seconds_total         | Counter   | 11.1  | Time spent by Ruby in GC |
 | ruby_gc_stat_...                       | Gauge     | 11.1  | Various metrics from [GC.stat] |
 | ruby_file_descriptors                  | Gauge     | 11.1  | File descriptors per process |
-| ruby_process_resident_memory_bytes     | Gauge     | 11.1  | Memory usage by process |
+| ruby_memory_bytes                      | Gauge     | 11.1  | Memory usage by process |
 | ruby_sampler_duration_seconds_total    | Counter   | 11.1  | Time spent collecting stats |
-| ruby_process_cpu_seconds_total         | Gauge     | 11.11 | Total amount of cpu time per process |
+| ruby_process_cpu_seconds_total         | Gauge     | 11.11 | Total amount of CPU time per process |
 | ruby_process_max_fds                   | Gauge     | 11.11 | Maximum number of open file descriptors per process |
+| ruby_process_resident_memory_bytes     | Gauge     | 11.11 | Memory usage by process |
 | ruby_process_start_time_seconds        | Gauge     | 11.11 | The time the process started after system boot in seconds |
 
 [GC.stat]: https://ruby-doc.org/core-2.3.0/GC.html#method-c-stat

lib/gitlab/metrics/samplers/ruby_sampler.rb

@@ -25,6 +25,7 @@ module Gitlab
         def init_metrics
           metrics = {
             file_descriptors:               ::Gitlab::Metrics.gauge(with_prefix(:file, :descriptors), 'File descriptors used', labels, :livesum),
+            memory_bytes:                   ::Gitlab::Metrics.gauge(with_prefix(:memory, :bytes), 'Memory used', labels, :livesum),
             process_cpu_seconds_total:      ::Gitlab::Metrics.gauge(with_prefix(:process, :cpu_seconds_total), 'Process CPU seconds total'),
             process_max_fds:                ::Gitlab::Metrics.gauge(with_prefix(:process, :max_fds), 'Process max fds'),
             process_resident_memory_bytes:  ::Gitlab::Metrics.gauge(with_prefix(:process, :resident_memory_bytes), 'Memory used', labels, :livesum),
@@ -46,8 +47,8 @@ module Gitlab
           metrics[:file_descriptors].set(labels.merge(worker_label), System.file_descriptor_count)
           metrics[:process_cpu_seconds_total].set(labels.merge(worker_label), ::Gitlab::Metrics::System.cpu_time)
           metrics[:process_max_fds].set(labels.merge(worker_label), ::Gitlab::Metrics::System.max_open_file_descriptors)
-          metrics[:process_resident_memory_bytes].set(labels.merge(worker_label), System.memory_usage)
           metrics[:process_start_time_seconds].set(labels.merge(worker_label), ::Gitlab::Metrics::System.process_start_time)
+          set_memory_usage_metrics
           sample_gc
 
           metrics[:sampler_duration].increment(labels, System.monotonic_time - start_time)
@@ -67,6 +68,14 @@ module Gitlab
           metrics[:total_time].increment(labels, GC::Profiler.total_time)
         end
 
+        def set_memory_usage_metrics
+          memory_usage = System.memory_usage
+          memory_labels = labels.merge(worker_label)
+
+          metrics[:memory_bytes].set(memory_labels, memory_usage)
+          metrics[:process_resident_memory_bytes].set(memory_labels, memory_usage)
+        end
+
         def worker_label
           return {} unless defined?(Unicorn::Worker)
 

lib/gitlab/metrics/samplers/unicorn_sampler.rb

@@ -27,13 +27,10 @@ module Gitlab
 
         def sample
           Raindrops::Linux.tcp_listener_stats(tcp_listeners).each do |addr, stats|
-            metrics[:unicorn_active_connections].set({ socket_type: 'tcp', socket_address: addr }, stats.active)
-            metrics[:unicorn_queued_connections].set({ socket_type: 'tcp', socket_address: addr }, stats.queued)
+            set_unicorn_connection_metrics('tcp', addr, stats)
           end
-
           Raindrops::Linux.unix_listener_stats(unix_listeners).each do |addr, stats|
-            metrics[:unicorn_active_connections].set({ socket_type: 'unix', socket_address: addr }, stats.active)
-            metrics[:unicorn_queued_connections].set({ socket_type: 'unix', socket_address: addr }, stats.queued)
+            set_unicorn_connection_metrics('unix', addr, stats)
           end
 
           metrics[:unicorn_workers].set({}, unicorn_workers_count)
@@ -45,8 +42,11 @@ module Gitlab
           @tcp_listeners ||= Unicorn.listener_names.grep(%r{\A[^/]+:\d+\z})
         end
 
-        def pid
-          @pid ||= Process.pid
+        def set_unicorn_connection_metrics(type, addr, stats)
+          labels = { socket_type: type, socket_address: addr }
+
+          metrics[:unicorn_active_connections].set(labels, stats.active)
+          metrics[:unicorn_queued_connections].set(labels, stats.queued)
         end
 
         def unix_listeners
@@ -58,7 +58,7 @@ module Gitlab
         end
 
         def unicorn_workers_count
-          Sys::ProcTable.ps.select {|p| p.cmdline.match(/unicorn_rails worker/)}.count
+          Sys::ProcTable.ps.select {|p| p.cmdline.match(/unicorn_rails worker.+ #{Rails.root.to_s}/)}.count
         end
       end
     end