fix(chaos): rate-limit tight-loop antagonists to prevent long-run OOM

ddprof-stresstest/src/chaos/java/com/datadoghq/profiler/chaos/ClassLoaderChurnAntagonist.java

@@ -77,6 +77,14 @@ private void loop() {
                 // transient; JVM crash is the signal we watch for
             }
             // loader + klass go out of scope here.
+            // Pace class loading so old-gen GC can reclaim ClassLoader
+            // instances before they accumulate across a long run.
+            try {
+                Thread.sleep(1L);
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                return;
+            }
         }
     }
 

ddprof-stresstest/src/chaos/java/com/datadoghq/profiler/chaos/HiddenClassChurnAntagonist.java

@@ -102,6 +102,14 @@ private void loop() {
             } catch (Throwable t) {
                 // transient; JVM crash is the signal we watch for
             }
+            // Pace hidden-class generation so the GC can evict unloaded
+            // classes before they accumulate across a long run.
+            try {
+                Thread.sleep(1L);
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                return;
+            }
         }
     }
 

ddprof-stresstest/src/chaos/java/com/datadoghq/profiler/chaos/WeakRefWaveAntagonist.java

@@ -31,6 +31,7 @@ public final class WeakRefWaveAntagonist implements Antagonist {
 
     private static final int WAVE_SIZE = 10_000;
     private static final int[] OBJECT_SIZES = {64, 256, 1_024, 4_096};
+    private static final long INTER_WAVE_MS = 200L;
 
     private volatile boolean running;
     private Thread waveDriver;
@@ -100,6 +101,15 @@ private void waveLoop() {
 
             // Replace shared reference; weakRefs goes out of scope
             currentWave = new ArrayList<WeakReference<byte[]>>();
+
+            // Pause between waves so concurrent GC can reclaim without being
+            // overwhelmed by back-to-back System.gc() calls.
+            try {
+                Thread.sleep(INTER_WAVE_MS);
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                return;
+            }
         }
     }