add logging

Author: wenyihu6

pkg/kv/kvserver/queue.go

@@ -772,7 +772,10 @@ func (bq *baseQueue) addInternal(
 	// priority element, but it would require additional bookkeeping or a linear
 	// scan.
 	if pqLen := bq.mu.priorityQ.Len(); pqLen > bq.maxSize {
-		bq.removeLocked(bq.mu.priorityQ.sl[pqLen-1])
+		replicaItemToDrop := bq.mu.priorityQ.sl[pqLen-1]
+		log.Dev.VInfof(ctx, 1, "dropping due to exceeding queue max size: priority=%0.3f, replica=%v",
+			priority, replicaItemToDrop.replicaID)
+		bq.removeLocked(replicaItemToDrop)
 	}
 	// Signal the processLoop that a replica has been added.
 	select {