From 832549744b0791b8a2556dd85fcfc231996fc777 Mon Sep 17 00:00:00 2001
From: Trask Stalnaker <trask.stalnaker@gmail.com>
Date: Wed, 5 Apr 2023 14:40:51 -0700
Subject: [PATCH] Add comment about active request count attributes (#8221)

---
 .../api/instrumenter/http/HttpServerMetrics.java                | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/instrumentation-api-semconv/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpServerMetrics.java b/instrumentation-api-semconv/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpServerMetrics.java
index abaddb42dd..3c355356f8 100644
--- a/instrumentation-api-semconv/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpServerMetrics.java
+++ b/instrumentation-api-semconv/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/http/HttpServerMetrics.java
@@ -102,6 +102,8 @@ public final class HttpServerMetrics implements OperationListener {
           context);
       return;
     }
+    // it's important to use exactly the same attributes that were used when incrementing the active
+    // request count (otherwise it will split the timeseries)
     activeRequests.add(-1, applyActiveRequestsView(state.startAttributes()), context);
     Attributes durationAndSizeAttributes =
         applyServerDurationAndSizeView(state.startAttributes(), endAttributes);