Add memory usage fallback

Signed-off-by: Lantao Jin <ltjin@amazon.com>

Author: LantaoJin

opensearch/src/main/java/org/opensearch/sql/opensearch/monitor/GCedMemoryUsage.java

@@ -56,10 +56,12 @@ public void setUsage(long value) {
   }
 
   private void registerGCListener() {
+    boolean registered = false;
     List<GarbageCollectorMXBean> gcBeans = ManagementFactory.getGarbageCollectorMXBeans();
     for (GarbageCollectorMXBean gcBean : gcBeans) {
       if (gcBean instanceof NotificationEmitter && isOldGenGc(gcBean.getName())) {
         LOG.info("{} listener registered for memory usage monitor.", gcBean.getName());
+        registered = true;
         NotificationEmitter emitter = (NotificationEmitter) gcBean;
         emitter.addNotificationListener(
             new OldGenGCListener(),
@@ -76,6 +78,11 @@ private void registerGCListener() {
             null);
       }
     }
+    if (!registered) {
+      // fallback to RuntimeMemoryUsage
+      LOG.info("No old gen GC listener registered, fallback to RuntimeMemoryUsage");
+      throw new OpenSearchMemoryHealthy.MemoryUsageException();
+    }
   }
 
   private boolean isOldGenGc(String gcKeyword) {

opensearch/src/main/java/org/opensearch/sql/opensearch/monitor/OpenSearchMemoryHealthy.java

@@ -19,10 +19,7 @@ public class OpenSearchMemoryHealthy {
 
   public OpenSearchMemoryHealthy(Settings settings) {
     randomFail = new RandomFail();
-    memoryUsage =
-        isCalciteEnabled(settings)
-            ? GCedMemoryUsage.getInstance()
-            : RuntimeMemoryUsage.getInstance();
+    memoryUsage = buildMemoryUsage(settings);
   }
 
   @VisibleForTesting
@@ -31,6 +28,16 @@ public OpenSearchMemoryHealthy(RandomFail randomFail, MemoryUsage memoryUsage) {
     this.memoryUsage = memoryUsage;
   }
 
+  private MemoryUsage buildMemoryUsage(Settings settings) {
+    try {
+      return isCalciteEnabled(settings)
+          ? GCedMemoryUsage.getInstance()
+          : RuntimeMemoryUsage.getInstance();
+    } catch (MemoryUsageException e) {
+      return RuntimeMemoryUsage.getInstance();
+    }
+  }
+
   private boolean isCalciteEnabled(Settings settings) {
     if (settings != null) {
       return settings.getSettingValue(Settings.Key.CALCITE_ENGINE_ENABLED);
@@ -63,8 +70,11 @@ public boolean shouldFail() {
   }
 
   @NoArgsConstructor
-  public static class MemoryUsageExceedFastFailureException extends RuntimeException {}
+  public static class MemoryUsageExceedFastFailureException extends MemoryUsageException {}
+
+  @NoArgsConstructor
+  public static class MemoryUsageExceedException extends MemoryUsageException {}
 
   @NoArgsConstructor
-  public static class MemoryUsageExceedException extends RuntimeException {}
+  public static class MemoryUsageException extends RuntimeException {}
 }