Add metrics for tracking partial granularity (#1560)

Author: hmstepanek

newrelic/core/application.py

@@ -1373,6 +1373,11 @@ def harvest(self, shutdown=False, flexible=False):
                                 spans_sampled = spans.num_samples
                                 internal_count_metric("Supportability/SpanEvent/TotalEventsSeen", spans_seen)
                                 internal_count_metric("Supportability/SpanEvent/TotalEventsSent", spans_sampled)
+                                if configuration.distributed_tracing.sampler.partial_granularity.enabled:
+                                    internal_count_metric(
+                                        f"Supportability/Python/PartialGranularity/{configuration.distributed_tracing.sampler.partial_granularity.type}",
+                                        1,
+                                    )
 
                                 stats.reset_span_events()
 

newrelic/core/node_mixin.py

@@ -162,8 +162,10 @@ def span_events(
             partial_granularity_sampled=partial_granularity_sampled,
             ct_exit_spans=ct_exit_spans,
         )
+        ct_exit_spans["instrumented"] += 1
         parent_id = parent_guid
         if span:  # span will be None if the span is an inprocess span or repeated exit span.
+            ct_exit_spans["kept"] += 1
             yield span
             # Compressed spans are always reparented onto the entry span.
             if not settings.distributed_tracing.sampler.partial_granularity.type == "compact" or span[0].get(
@@ -179,7 +181,9 @@ def span_events(
                 partial_granularity_sampled=partial_granularity_sampled,
                 ct_exit_spans=ct_exit_spans,
             ):
+                ct_exit_spans["instrumented"] += 1
                 if event:  # event will be None if the span is an inprocess span or repeated exit span.
+                    ct_exit_spans["kept"] += 1
                     yield event
 
 

newrelic/core/stats_engine.py

@@ -1190,6 +1190,20 @@ def record_transaction(self, transaction):
             elif transaction.sampled:
                 for event in transaction.span_events(self.__settings):
                     self._span_events.add(event, priority=transaction.priority)
+                if transaction.partial_granularity_sampled:
+                    partial_gran_type = settings.distributed_tracing.sampler.partial_granularity.type
+                    self.record_custom_metrics(
+                        [
+                            (
+                                f"Supportability/DistributedTrace/PartialGranularity/{partial_gran_type}/Span/Instrumented",
+                                {"count": transaction.instrumented},
+                            ),
+                            (
+                                f"Supportability/DistributedTrace/PartialGranularity/{partial_gran_type}/Span/Kept",
+                                {"count": transaction.kept},
+                            ),
+                        ]
+                    )
 
         # Merge in log events
 

newrelic/core/transaction_node.py

@@ -634,7 +634,7 @@ def span_events(self, settings, attr_class=dict):
                 ("priority", self.priority),
             )
         )
-        ct_exit_spans = {}
+        ct_exit_spans = {"instrumented": 0, "kept": 0}
         yield from self.root.span_events(
             settings,
             base_attrs,
@@ -643,3 +643,9 @@ def span_events(self, settings, attr_class=dict):
             partial_granularity_sampled=self.partial_granularity_sampled,
             ct_exit_spans=ct_exit_spans,
         )
+        # If this transaction is partial granularity sampled, record the number of spans
+        # instrumented and the number of spans kept to monitor cost savings of partial
+        # granularity tracing.
+        if self.partial_granularity_sampled:
+            self.instrumented = ct_exit_spans["instrumented"]
+            self.kept = ct_exit_spans["kept"]