Stresstest fix - Add limits to the graph mutation stress test

Author: r1viollet

ddprof-stresstest/src/jmh/java/com/datadoghq/profiler/stresstest/scenarios/counters/GraphMutation.java

@@ -3,17 +3,27 @@
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.Threads;
 
-import java.util.Queue;
-import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.atomic.AtomicReferenceArray;
 
 public class GraphMutation {
 
     public static class GraphNode {
-        private final Queue<GraphNode> nodes = new ConcurrentLinkedQueue<>();
+        // Use a fixed-size array instead of unbounded queue
+        // This naturally bounds memory while still allowing realistic stress testing
+        private static final int MAX_LINKS = 10000;
+        private final AtomicReferenceArray<GraphNode> links = new AtomicReferenceArray<>(MAX_LINKS);
+        private volatile int linkIndex = 0;
 
         public void link(GraphNode node) {
-            nodes.add(node);
+            // Simple round-robin replacement - no expensive size checks or polling
+            int index = (linkIndex++) % MAX_LINKS;
+            links.set(index, node);
+        }
+
+        // Optional: method to access links if needed for verification
+        public GraphNode getLink(int index) {
+            return links.get(index % MAX_LINKS);
         }
     }