Reduce newEvictedQueueLink and newEvictedQueueEvent memory allocations

CHANGELOG.md

@@ -18,6 +18,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - `Logger.Enabled` in `go.opentelemetry.io/otel/log` now accepts a newly introduced `EnabledParameters` type instead of `Record`. (#5791)
 - `FilterProcessor.Enabled` in `go.opentelemetry.io/otel/sdk/log/internal/x` now accepts `EnabledParameters` instead of `Record`. (#5791)
 - The `Record` type in `go.opentelemetry.io/otel/log` is no longer comparable. (#5847)
+- Reduce `newEvictedQueueLink` and `newEvictedQueueEvent` memory allocations. (#5858)
 
 ### Deprecated
 

sdk/trace/evictedqueue.go

@@ -12,25 +12,26 @@ import (
 
 // evictedQueue is a FIFO queue with a configurable capacity.
 type evictedQueue[T any] struct {
-	queue        []T
-	capacity     int
-	droppedCount int
-	logDropped   func()
+	queue          []T
+	capacity       int
+	droppedCount   int
+	logDroppedFunc func()
+	logDroppedOnce sync.Once
 }
 
 func newEvictedQueueEvent(capacity int) evictedQueue[Event] {
 	// Do not pre-allocate queue, do this lazily.
 	return evictedQueue[Event]{
-		capacity:   capacity,
-		logDropped: sync.OnceFunc(func() { global.Warn("limit reached: dropping trace trace.Event") }),
+		capacity:       capacity,
+		logDroppedFunc: func() { global.Warn("limit reached: dropping trace trace.Event") },
 	}
 }
 
 func newEvictedQueueLink(capacity int) evictedQueue[Link] {
 	// Do not pre-allocate queue, do this lazily.
 	return evictedQueue[Link]{
-		capacity:   capacity,
-		logDropped: sync.OnceFunc(func() { global.Warn("limit reached: dropping trace trace.Link") }),
+		capacity:       capacity,
+		logDroppedFunc: func() { global.Warn("limit reached: dropping trace trace.Link") },
 	}
 }
 
@@ -53,6 +54,10 @@ func (eq *evictedQueue[T]) add(value T) {
 	eq.queue = append(eq.queue, value)
 }
 
+func (eq *evictedQueue[T]) logDropped() {
+	eq.logDroppedOnce.Do(eq.logDroppedFunc)
+}
+
 // copy returns a copy of the evictedQueue.
 func (eq *evictedQueue[T]) copy() []T {
 	return slices.Clone(eq.queue)

sdk/trace/evictedqueue_test.go

@@ -37,7 +37,7 @@ func TestCopy(t *testing.T) {
 func TestDropCount(t *testing.T) {
 	q := newEvictedQueueEvent(3)
 	var called bool
-	q.logDropped = func() { called = true }
+	q.logDroppedFunc = func() { called = true }
 
 	q.add(Event{Name: "value1"})
 	assert.False(t, called, `"value1" logged as dropped`)