Add marking and sweeping time as Process stat (#300)

* Add marking and sweeping time as Process stat

Introduced in https://bugs.ruby-lang.org/issues/19437

* Do provide marking_time and sweeping_time on Ruby version bellow 3.3

Author: benoittgt

README.md

@@ -373,6 +373,8 @@ end
 | Counter | `major_gc_ops_total`      | Major GC operations by process               |
 | Counter | `minor_gc_ops_total`      | Minor GC operations by process               |
 | Counter | `allocated_objects_total` | Total number of allocated objects by process |
+| Gauge   | `marking_time`            | Marking time spent (Ruby 3.3 minimum)        |
+| Gauge   | `sweeping_time`           | Sweeping time spent (Ruby 3.3 minimum)       |
 
 _Metrics marked with * are only collected when `MiniRacer` is defined._
 

lib/prometheus_exporter/instrumentation/process.rb

@@ -62,6 +62,8 @@ def collect_process_stats(metric)
       metric[:rss] = rss
     end
 
+    SWEEPING_AND_MARKING = RUBY_VERSION >= "3.3.0"
+
     def collect_gc_stats(metric)
       stat = GC.stat
       metric[:heap_live_slots] = stat[:heap_live_slots]
@@ -71,6 +73,10 @@ def collect_gc_stats(metric)
       metric[:allocated_objects_total] = stat[:total_allocated_objects]
       metric[:malloc_increase_bytes_limit] = stat[:malloc_increase_bytes_limit]
       metric[:oldmalloc_increase_bytes_limit] = stat[:oldmalloc_increase_bytes_limit]
+      if SWEEPING_AND_MARKING
+        metric[:marking_time] = stat[:marking_time]
+        metric[:sweeping_time] = stat[:sweeping_time]
+      end
     end
 
     def collect_v8_stats(metric)

lib/prometheus_exporter/server/process_collector.rb

@@ -16,6 +16,8 @@ class ProcessCollector < TypeCollector
         "Limit before Ruby triggers a GC against current objects (bytes).",
       oldmalloc_increase_bytes_limit:
         "Limit before Ruby triggers a major GC against old objects (bytes).",
+      marking_time: "Time spent in GC marking.",
+      sweeping_time: "Time spent in GC sweeping.",
     }
 
     PROCESS_COUNTERS = {

test/server/process_collector_test.rb

@@ -27,13 +27,15 @@ def base_data
       "major_gc_ops_total" => 4000,
       "minor_gc_ops_total" => 4001,
       "allocated_objects_total" => 4002,
+      "marking_time" => 4003,
+      "sweeping_time" => 4004,
     }
   end
 
   def test_metrics_collection
     collector.collect(base_data)
 
-    assert_equal 10, collector.metrics.size
+    assert_equal 12, collector.metrics.size
     assert_equal [
                    'heap_free_slots{pid="1000",hostname="localhost"} 1000',
                    'heap_live_slots{pid="1000",hostname="localhost"} 1001',
@@ -42,6 +44,8 @@ def test_metrics_collection
                    'v8_physical_size{pid="1000",hostname="localhost"} 2003',
                    'v8_heap_count{pid="1000",hostname="localhost"} 2004',
                    'rss{pid="1000",hostname="localhost"} 3000',
+                   'marking_time{pid="1000",hostname="localhost"} 4003',
+                   'sweeping_time{pid="1000",hostname="localhost"} 4004',
                    'major_gc_ops_total{pid="1000",hostname="localhost"} 4000',
                    'minor_gc_ops_total{pid="1000",hostname="localhost"} 4001',
                    'allocated_objects_total{pid="1000",hostname="localhost"} 4002',
@@ -51,22 +55,22 @@ def test_metrics_collection
 
   def test_metrics_deduplication
     collector.collect(base_data)
-    assert_equal 10, collector.metrics.size
-    assert_equal 10, collector_metric_lines.size
+    assert_equal 12, collector.metrics.size
+    assert_equal 12, collector_metric_lines.size
 
     collector.collect(base_data)
-    assert_equal 10, collector.metrics.size
-    assert_equal 10, collector_metric_lines.size
+    assert_equal 12, collector.metrics.size
+    assert_equal 12, collector_metric_lines.size
 
     collector.collect(base_data.merge({ "hostname" => "localhost2" }))
-    assert_equal 10, collector.metrics.size
-    assert_equal 20, collector_metric_lines.size
+    assert_equal 12, collector.metrics.size
+    assert_equal 24, collector_metric_lines.size
   end
 
   def test_metrics_expiration
     stub_monotonic_clock(0) do
       collector.collect(base_data)
-      assert_equal 10, collector.metrics.size
+      assert_equal 12, collector.metrics.size
     end
 
     stub_monotonic_clock(max_metric_age + 1) { assert_equal 0, collector.metrics.size }