Expose worker_count in utilization metrics.

Author: samuel-williams-shopify

lib/async/service/supervisor/utilization_monitor.rb

@@ -303,6 +303,9 @@ def as_json
 									aggregated[service_name][key] = value
 								end
 							end
+							
+							# Count workers per service (for utilization denominator)
+							aggregated[service_name][:worker_count] = (aggregated[service_name][:worker_count] || 0) + 1
 						end
 
 						aggregated

releases.md

@@ -1,5 +1,9 @@
 # Releases
 
+## Unreleased
+
+  - Add `worker_count` to `UtilizationMonitor` aggregated metrics per service, indicating how many workers contributed to each service's metrics (useful for utilization denominator).
+
 ## v0.12.0
 
   - Introduce `UtilizationMonitor`, that uses shared memory to track worker utilization metrics, like total and active requests, connections, etc.

test/async/service/utilization_monitor.rb

@@ -122,7 +122,8 @@
 		status = monitor.status
 		expect(status[:data]["test_service"]).to have_keys(
 			connections_total: be == 100,
-			connections_active: be == 5
+			connections_active: be == 5,
+			worker_count: be == 1
 		)
 	end
 
@@ -157,7 +158,8 @@
 		status = monitor.status
 		expect(status[:data]["test_service"]).to have_keys(
 			connections_total: be == 125,  # 50 + 75
-			connections_active: be == 5    # 3 + 2
+			connections_active: be == 5,   # 3 + 2
+			worker_count: be == 2          # two workers for same service
 		)
 	end
 
@@ -193,11 +195,13 @@
 		expect(status[:data]).to have_keys("test_service", "other_service")
 		expect(status[:data]["test_service"]).to have_keys(
 			connections_total: be == 100,
-			connections_active: be == 5
+			connections_active: be == 5,
+			worker_count: be == 1
 		)
 		expect(status[:data]["other_service"]).to have_keys(
 			connections_total: be == 200,
-			connections_active: be == 10
+			connections_active: be == 10,
+			worker_count: be == 1
 		)
 	end
 
@@ -224,7 +228,8 @@
 		status = monitor.status
 		expect(status[:data]).to have_keys("unknown")
 		expect(status[:data]["unknown"]).to have_keys(
-			connections_total: be == 50
+			connections_total: be == 50,
+			worker_count: be == 1
 		)
 	end